SONAR-9739 add WS api/system/health

29 files changed, 1700 insertions, 1 deletions

diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/DbConnectionCheck.java b/server/sonar-server/src/main/java/org/sonar/server/health/DbConnectionCheck.java
new file mode 100644
index 00000000000..7d43d29f0ae
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/DbConnectionCheck.java
@@ -0,0 +1,59 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import org.sonar.api.utils.log.Logger;
+import org.sonar.api.utils.log.Loggers;
+import org.sonar.db.DbClient;
+import org.sonar.db.DbSession;
+import org.sonar.db.IsAliveMapper;
+
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+/**
+ * Checks Web Server can connect to the Database.
+ */
+public class DbConnectionCheck implements HealthCheck {
+  private static final Logger LOGGER = Loggers.get(DbConnectionCheck.class);
+  private static final Health RED_HEALTH = newHealthCheckBuilder().setStatus(Health.Status.RED).addCause("Can't connect to DB").build();
+
+  private final DbClient dbClient;
+
+  public DbConnectionCheck(DbClient dbClient) {
+    this.dbClient = dbClient;
+  }
+
+  @Override
+  public Health check() {
+    if (isConnectedToDB()) {
+      return Health.GREEN;
+    }
+    return RED_HEALTH;
+  }
+
+  private boolean isConnectedToDB() {
+    try (DbSession dbSession = dbClient.openSession(false)) {
+      return dbSession.getMapper(IsAliveMapper.class).isAlive() == IsAliveMapper.IS_ALIVE_RETURNED_VALUE;
+    } catch (RuntimeException e) {
+      LOGGER.trace("DB connection is down", e);
+      return false;
+    }
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/EsStatusCheck.java b/server/sonar-server/src/main/java/org/sonar/server/health/EsStatusCheck.java
new file mode 100644
index 00000000000..cdf086082c9
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/EsStatusCheck.java
@@ -0,0 +1,60 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import org.elasticsearch.cluster.health.ClusterHealthStatus;
+import org.sonar.server.es.EsClient;
+
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+/**
+ * Checks the ElasticSearch cluster status.
+ */
+public class EsStatusCheck implements HealthCheck {
+  private static final Health YELLOW_HEALTH = newHealthCheckBuilder()
+    .setStatus(Health.Status.YELLOW)
+    .addCause("Elasticsearch status is YELLOW")
+    .build();
+  private static final Health RED_HEALTH = newHealthCheckBuilder()
+    .setStatus(Health.Status.RED)
+    .addCause("Elasticsearch status is RED")
+    .build();
+
+  private final EsClient esClient;
+
+  public EsStatusCheck(EsClient esClient) {
+    this.esClient = esClient;
+  }
+
+  @Override
+  public Health check() {
+    ClusterHealthStatus esStatus = esClient.prepareClusterStats().get().getStatus();
+    switch (esStatus) {
+      case GREEN:
+        return Health.GREEN;
+      case YELLOW:
+        return YELLOW_HEALTH;
+      case RED:
+        return RED_HEALTH;
+      default:
+        throw new IllegalArgumentException("Unsupported Elasticsearch status " + esStatus);
+    }
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/Health.java b/server/sonar-server/src/main/java/org/sonar/server/health/Health.java
new file mode 100644
index 00000000000..065b64a5771
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/Health.java
@@ -0,0 +1,136 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.requireNonNull;
+
+public class Health {
+  /**
+   * The GREEN status without any cause as a constant, for convenience and optimisation.
+   */
+  static final Health GREEN = newHealthCheckBuilder()
+    .setStatus(Status.GREEN)
+    .build();
+
+  private final Status status;
+  private final Set<String> causes;
+
+  public Health(Builder builder) {
+    this.status = builder.status;
+    this.causes = ImmutableSet.copyOf(builder.causes);
+  }
+
+  public Status getStatus() {
+    return status;
+  }
+
+  public Set<String> getCauses() {
+    return causes;
+  }
+
+  public static Builder newHealthCheckBuilder() {
+    return new Builder();
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    Health health = (Health) o;
+    return status == health.status &&
+      Objects.equals(causes, health.causes);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(status, causes);
+  }
+
+  @Override
+  public String toString() {
+    return "Health{" + status +
+      ", causes=" + causes +
+      '}';
+  }
+
+  /**
+   * Builder of {@link Health} which supports being reused for optimization.
+   */
+  public static class Builder {
+    private Status status;
+    private Set<String> causes = new HashSet<>(0);
+
+    private Builder() {
+      // use static factory method
+    }
+
+    public Builder clear() {
+      this.status = null;
+      this.causes.clear();
+      return this;
+    }
+
+    public Builder setStatus(Status status) {
+      this.status = checkStatus(status);
+      return this;
+    }
+
+    public Builder addCause(String cause) {
+      requireNonNull(cause, "cause can't be null");
+      checkArgument(!cause.trim().isEmpty(), "cause can't be empty");
+      causes.add(cause);
+      return this;
+    }
+
+    public Health build() {
+      checkStatus(this.status);
+      return new Health(this);
+    }
+
+    private static Status checkStatus(Status status) {
+      return requireNonNull(status, "status can't be null");
+    }
+  }
+
+  public enum Status {
+    /**
+     * Fully working
+     */
+    GREEN,
+    /**
+     * Yellow: Working but something must be fixed to make SQ fully operational
+     */
+    YELLOW,
+    /**
+     * Red: Not working
+     */
+    RED
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheck.java b/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheck.java
new file mode 100644
index 00000000000..f52f9225003
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheck.java
@@ -0,0 +1,24 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+public interface HealthCheck {
+  Health check();
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/HealthChecker.java b/server/sonar-server/src/main/java/org/sonar/server/health/HealthChecker.java
new file mode 100644
index 00000000000..48d1f94a273
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/HealthChecker.java
@@ -0,0 +1,27 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+public interface HealthChecker {
+  /**
+   * Perform a check of the health of SonarQube, either as a standalone node or as a cluster.
+   */
+  Health check();
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheckerImpl.java b/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheckerImpl.java
new file mode 100644
index 00000000000..e45e8cd599c
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/HealthCheckerImpl.java
@@ -0,0 +1,77 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.BinaryOperator;
+import java.util.stream.Stream;
+
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+/**
+ * Implementation of {@link HealthChecker} that executes implementations of {@link HealthCheck} in the container
+ * and aggregates their results.
+ */
+public class HealthCheckerImpl implements HealthChecker {
+  private final List<HealthCheck> healthChecks;
+
+  public HealthCheckerImpl(HealthCheck... healthChecks) {
+    this.healthChecks = Arrays.asList(healthChecks);
+  }
+
+  @Override
+  public Health check() {
+    return healthChecks.stream().map(HealthCheck::check)
+      .reduce(Health.GREEN, HealthReducer.INSTANCE);
+  }
+
+  private enum HealthReducer implements BinaryOperator<Health> {
+    INSTANCE;
+
+    /**
+     * According to Javadoc, {@link BinaryOperator} used in method
+     * {@link java.util.stream.Stream#reduce(Object, BinaryOperator)} is supposed to be stateless.
+     *
+     * But as we are sure this {@link BinaryOperator} won't be used on a Stream with {@link Stream#parallel()}
+     * feature on, we allow ourselves this optimisation.
+     */
+    private final Health.Builder builder = newHealthCheckBuilder();
+
+    @Override
+    public Health apply(Health left, Health right) {
+      builder.clear();
+      builder.setStatus(worseOf(left.getStatus(), right.getStatus()));
+      left.getCauses().forEach(builder::addCause);
+      right.getCauses().forEach(builder::addCause);
+      return builder.build();
+    }
+
+    private static Health.Status worseOf(Health.Status left, Health.Status right) {
+      if (left == right) {
+        return left;
+      }
+      if (left.ordinal() > right.ordinal()) {
+        return left;
+      }
+      return right;
+    }
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/WebServerSafemodeCheck.java b/server/sonar-server/src/main/java/org/sonar/server/health/WebServerSafemodeCheck.java
new file mode 100644
index 00000000000..09a1cdc2e46
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/WebServerSafemodeCheck.java
@@ -0,0 +1,39 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+/**
+ * Checks the running status of the WebServer when the WebServer is in safemode.
+ * Obviously, it statically returns a red health status.
+ */
+public class WebServerSafemodeCheck implements HealthCheck {
+
+  private static final Health RED_HEALTH = newHealthCheckBuilder()
+    .setStatus(Health.Status.RED)
+    .addCause("SonarQube webserver is not up")
+    .build();
+
+  @Override
+  public Health check() {
+    return RED_HEALTH;
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/WebServerStatusCheck.java b/server/sonar-server/src/main/java/org/sonar/server/health/WebServerStatusCheck.java
new file mode 100644
index 00000000000..2146a315d4d
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/WebServerStatusCheck.java
@@ -0,0 +1,59 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import java.util.EnumSet;
+import org.sonar.server.app.RestartFlagHolder;
+import org.sonar.server.platform.Platform;
+import org.sonar.server.platform.db.migration.DatabaseMigrationState;
+
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+/**
+ * Checks the running status of the WebServer when it is not anymore in safemode.
+ */
+public class WebServerStatusCheck implements HealthCheck {
+  private static final EnumSet<DatabaseMigrationState.Status> VALID_DATABASEMIGRATION_STATUSES = EnumSet.of(
+    DatabaseMigrationState.Status.NONE, DatabaseMigrationState.Status.SUCCEEDED);
+
+  private final DatabaseMigrationState migrationState;
+  private final Platform platform;
+  private final RestartFlagHolder restartFlagHolder;
+
+  public WebServerStatusCheck(DatabaseMigrationState migrationState, Platform platform, RestartFlagHolder restartFlagHolder) {
+    this.migrationState = migrationState;
+    this.platform = platform;
+    this.restartFlagHolder = restartFlagHolder;
+  }
+
+  @Override
+  public Health check() {
+    Platform.Status platformStatus = platform.status();
+    if (platformStatus == Platform.Status.UP
+      && VALID_DATABASEMIGRATION_STATUSES.contains(migrationState.getStatus())
+      && !restartFlagHolder.isRestarting()) {
+      return Health.GREEN;
+    }
+    return newHealthCheckBuilder()
+      .setStatus(Health.Status.RED)
+      .addCause("SonarQube webserver is not up")
+      .build();
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/health/package-info.java b/server/sonar-server/src/main/java/org/sonar/server/health/package-info.java
new file mode 100644
index 00000000000..ce49c888b43
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/health/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.server.health;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevel4.java b/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevel4.java
index 6786bec8638..bda21231f0a 100644
--- a/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevel4.java
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevel4.java
@@ -117,6 +117,7 @@ import org.sonar.server.platform.web.WebPagesFilter;
 import org.sonar.server.platform.web.requestid.HttpRequestIdModule;
 import org.sonar.server.platform.ws.ChangeLogLevelAction;
 import org.sonar.server.platform.ws.DbMigrationStatusAction;
+import org.sonar.server.platform.ws.HealthActionModule;
 import org.sonar.server.platform.ws.InfoActionModule;
 import org.sonar.server.platform.ws.L10nWs;
 import org.sonar.server.platform.ws.LogsAction;
@@ -481,7 +482,6 @@ public class PlatformLevel4 extends PlatformLevel {
       PingAction.class,
       UpgradesAction.class,
       StatusAction.class,
-      SystemWs.class,
       SystemMonitor.class,
       SettingsMonitor.class,
       SonarQubeMonitor.class,
@@ -493,6 +493,8 @@ public class PlatformLevel4 extends PlatformLevel {
       LogsAction.class,
       ChangeLogLevelAction.class,
       DbMigrationStatusAction.class,
+      HealthActionModule.class,
+      SystemWs.class,
 
       // Server id
       ServerIdWsModule.class,
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevelSafeMode.java b/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevelSafeMode.java
index 23208b88d33..95ba0f135e2 100644
--- a/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevelSafeMode.java
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/platformlevel/PlatformLevelSafeMode.java
@@ -19,6 +19,7 @@
  */
 package org.sonar.server.platform.platformlevel;
 
+import org.sonar.server.platform.ws.SafeModeHealthActionModule;
 import org.sonar.server.organization.NoopDefaultOrganizationCache;
 import org.sonar.server.platform.ServerImpl;
 import org.sonar.server.platform.db.migration.AutoDbMigration;
@@ -55,6 +56,7 @@ public class PlatformLevelSafeMode extends PlatformLevel {
       StatusAction.class,
       MigrateDbAction.class,
       DbMigrationStatusAction.class,
+      SafeModeHealthActionModule.class,
       SystemWs.class,
 
       // Listing WS
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/ws/AbstractHealthAction.java b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/AbstractHealthAction.java
new file mode 100644
index 00000000000..c0a878b8b5e
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/AbstractHealthAction.java
@@ -0,0 +1,68 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import com.google.common.io.Resources;
+import org.sonar.api.server.ws.Request;
+import org.sonar.api.server.ws.Response;
+import org.sonar.api.server.ws.WebService;
+import org.sonar.server.health.Health;
+import org.sonar.server.health.HealthChecker;
+import org.sonar.server.ws.WsUtils;
+import org.sonarqube.ws.WsSystem;
+
+public abstract class AbstractHealthAction implements SystemWsAction {
+  private final HealthChecker healthChecker;
+
+  public AbstractHealthAction(HealthChecker healthChecker) {
+    this.healthChecker = healthChecker;
+  }
+
+  @Override
+  public void define(WebService.NewController controller) {
+    controller.createAction("health")
+      .setDescription("Provide health status of the current SonarQube instance." +
+        "<p>status: the health status" +
+        " <ul>" +
+        " <li>GREEN: SonarQube is fully operational</li>" +
+        " <li>YELLOW: SonarQube is operational but something must be fixed to be fully operational</li>" +
+        " <li>RED: SonarQube is not operational</li>" +
+        " </ul>" +
+        "</p>")
+      .setSince("6.6")
+      .setResponseExample(Resources.getResource(this.getClass(), "example-health.json"))
+      .setHandler(this);
+  }
+
+  @Override
+  public void handle(Request request, Response response) throws Exception {
+    performAuthenticationChecks();
+
+    Health check = healthChecker.check();
+    WsSystem.HealthResponse.Builder responseBuilder = WsSystem.HealthResponse.newBuilder()
+      .setHealth(WsSystem.Health.valueOf(check.getStatus().name()));
+    WsSystem.Cause.Builder causeBuilder = WsSystem.Cause.newBuilder();
+    check.getCauses().forEach(str -> responseBuilder.addCauses(causeBuilder.clear().setMessage(str).build()));
+
+    WsUtils.writeProtobuf(responseBuilder.build(), request, response);
+  }
+
+  abstract void performAuthenticationChecks();
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthAction.java b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthAction.java
new file mode 100644
index 00000000000..ab160d65e57
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthAction.java
@@ -0,0 +1,39 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import org.sonar.server.health.HealthChecker;
+import org.sonar.server.user.UserSession;
+
+public class HealthAction extends AbstractHealthAction {
+  private final UserSession userSession;
+
+  public HealthAction(UserSession userSession, HealthChecker healthChecker) {
+    super(healthChecker);
+    this.userSession = userSession;
+  }
+
+  @Override
+  void performAuthenticationChecks() {
+    userSession
+      .checkLoggedIn()
+      .checkIsSystemAdministrator();
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthActionModule.java b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthActionModule.java
new file mode 100644
index 00000000000..3e9b97aa487
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/HealthActionModule.java
@@ -0,0 +1,41 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import org.sonar.core.platform.Module;
+import org.sonar.server.health.DbConnectionCheck;
+import org.sonar.server.health.EsStatusCheck;
+import org.sonar.server.health.HealthCheckerImpl;
+import org.sonar.server.health.WebServerStatusCheck;
+
+public class HealthActionModule extends Module {
+  @Override
+  protected void configureModule() {
+    add(
+      // HealthCheck implementations
+      WebServerStatusCheck.class,
+      DbConnectionCheck.class,
+      EsStatusCheck.class,
+
+      HealthCheckerImpl.class,
+
+      HealthAction.class);
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthAction.java b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthAction.java
new file mode 100644
index 00000000000..f3248871603
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthAction.java
@@ -0,0 +1,33 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import org.sonar.server.health.HealthChecker;
+
+public class SafeModeHealthAction extends AbstractHealthAction {
+  public SafeModeHealthAction(HealthChecker healthChecker) {
+    super(healthChecker);
+  }
+
+  @Override
+  void performAuthenticationChecks() {
+    // no authentication check in safemode
+  }
+}
diff --git a/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthActionModule.java b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthActionModule.java
new file mode 100644
index 00000000000..a11df47a697
--- /dev/null
+++ b/server/sonar-server/src/main/java/org/sonar/server/platform/ws/SafeModeHealthActionModule.java
@@ -0,0 +1,40 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import org.sonar.core.platform.Module;
+import org.sonar.server.health.DbConnectionCheck;
+import org.sonar.server.health.EsStatusCheck;
+import org.sonar.server.health.HealthCheckerImpl;
+import org.sonar.server.health.WebServerSafemodeCheck;
+
+public class SafeModeHealthActionModule extends Module {
+  @Override
+  protected void configureModule() {
+    add(
+      // HealthCheck implementations
+      WebServerSafemodeCheck.class,
+      DbConnectionCheck.class,
+      EsStatusCheck.class,
+
+      HealthCheckerImpl.class,
+      SafeModeHealthAction.class);
+  }
+}
diff --git a/server/sonar-server/src/main/resources/org/sonar/server/platform/ws/example-health.json b/server/sonar-server/src/main/resources/org/sonar/server/platform/ws/example-health.json
new file mode 100644
index 00000000000..9d95994a7b4
--- /dev/null
+++ b/server/sonar-server/src/main/resources/org/sonar/server/platform/ws/example-health.json
@@ -0,0 +1,8 @@
+{
+  "health": "YELLOW",
+  "causes": [
+    {
+      "message": "Elasticsearch status is YELLOW"
+    }
+  ]
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/DbConnectionCheckTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/DbConnectionCheckTest.java
new file mode 100644
index 00000000000..41b8c3acd51
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/DbConnectionCheckTest.java
@@ -0,0 +1,81 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.sonar.db.DbClient;
+import org.sonar.db.DbSession;
+import org.sonar.db.IsAliveMapper;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Matchers.anyBoolean;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class DbConnectionCheckTest {
+  private DbClient dbClient = mock(DbClient.class);
+  private DbSession dbSession = mock(DbSession.class);
+  private IsAliveMapper isAliveMapper = mock(IsAliveMapper.class);
+
+  private DbConnectionCheck underTest = new DbConnectionCheck(dbClient);
+
+  @Before
+  public void wireMocks() {
+    when(dbClient.openSession(anyBoolean())).thenReturn(dbSession);
+    when(dbSession.getMapper(IsAliveMapper.class)).thenReturn(isAliveMapper);
+  }
+
+  @Test
+  public void status_is_GREEN_without_cause_if_isAlive_returns_1() {
+    when(isAliveMapper.isAlive()).thenReturn(1);
+
+    Health health = underTest.check();
+
+    assertThat(health).isEqualTo(Health.GREEN);
+  }
+
+  @Test
+  public void status_is_RED_with_single_cause_if_any_error_occurs_when_checking_DB() throws Exception {
+    when(isAliveMapper.isAlive()).thenThrow(new RuntimeException("simulated runtime exception when querying DB"));
+
+    Health health = underTest.check();
+
+    verifyRedStatus(health);
+  }
+
+  /**
+   * By contract {@link IsAliveMapper#isAlive()} can not return anything but 1. Still we write this test as a
+   * protection against change in this contract.
+   */
+  @Test
+  public void status_is_RED_with_single_cause_if_isAlive_does_not_return_1() throws Exception {
+    when(isAliveMapper.isAlive()).thenReturn(12);
+
+    Health health = underTest.check();
+
+    verifyRedStatus(health);
+  }
+
+  private void verifyRedStatus(Health health) {
+    assertThat(health.getStatus()).isEqualTo(Health.Status.RED);
+    assertThat(health.getCauses()).containsOnly("Can't connect to DB");
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/EsStatusCheckTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/EsStatusCheckTest.java
new file mode 100644
index 00000000000..0f8f0183843
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/EsStatusCheckTest.java
@@ -0,0 +1,42 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.sonar.server.es.EsTester;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class EsStatusCheckTest {
+
+  @Rule
+  public EsTester esTester = new EsTester();
+
+  private EsStatusCheck underTest = new EsStatusCheck(esTester.client());
+
+  @Test
+  public void check_returns_GREEN_without_cause_if_ES_cluster_status_is_GREEN() {
+    Health health = underTest.check();
+
+    assertThat(health).isEqualTo(Health.GREEN);
+  }
+
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/HealthCheckerImplTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/HealthCheckerImplTest.java
new file mode 100644
index 00000000000..ae91caeee7e
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/HealthCheckerImplTest.java
@@ -0,0 +1,126 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Random;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+import org.apache.commons.lang.RandomStringUtils;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.sonar.server.health.Health.Status.GREEN;
+import static org.sonar.server.health.Health.Status.RED;
+import static org.sonar.server.health.Health.Status.YELLOW;
+
+public class HealthCheckerImplTest {
+
+  private final Random random = new Random();
+
+  @Test
+  public void check_returns_green_status_without_any_cause_when_there_is_no_HealthCheck() {
+    HealthCheckerImpl underTest = new HealthCheckerImpl();
+
+    assertThat(underTest.check()).isEqualTo(Health.GREEN);
+  }
+
+  @Test
+  public void checks_returns_GREEN_status_if_only_GREEN_statuses_returned_by_HealthChecks() {
+    List<Health.Status> statuses = IntStream.range(1, 1 + random.nextInt(20)).mapToObj(i -> GREEN).collect(Collectors.toList());
+    HealthCheckerImpl underTest = newHealthCheckerImpl(statuses.stream());
+
+    assertThat(underTest.check().getStatus())
+      .describedAs("%s should have been computed from %s statuses", GREEN, statuses)
+      .isEqualTo(GREEN);
+  }
+
+  @Test
+  public void checks_returns_YELLOW_status_if_only_GREEN_and_at_least_one_YELLOW_statuses_returned_by_HealthChecks() {
+    List<Health.Status> statuses = new ArrayList<>();
+    Stream.concat(
+      IntStream.range(0, 1 + random.nextInt(20)).mapToObj(i -> YELLOW), // at least 1 YELLOW
+      IntStream.range(0, random.nextInt(20)).mapToObj(i -> GREEN)).forEach(statuses::add); // between 0 and 19 GREEN
+    Collections.shuffle(statuses);
+    HealthCheckerImpl underTest = newHealthCheckerImpl(statuses.stream());
+
+    assertThat(underTest.check().getStatus())
+      .describedAs("%s should have been computed from %s statuses", YELLOW, statuses)
+      .isEqualTo(YELLOW);
+  }
+
+  @Test
+  public void checks_returns_RED_status_if_at_least_one_RED_status_returned_by_HealthChecks() {
+    List<Health.Status> statuses = new ArrayList<>();
+    Stream.of(
+      IntStream.range(0, 1 + random.nextInt(20)).mapToObj(i -> RED), // at least 1 RED
+      IntStream.range(0, random.nextInt(20)).mapToObj(i -> YELLOW), // between 0 and 19 YELLOW
+      IntStream.range(0, random.nextInt(20)).mapToObj(i -> GREEN) // between 0 and 19 GREEN
+    ).flatMap(s -> s)
+      .forEach(statuses::add);
+    Collections.shuffle(statuses);
+    HealthCheckerImpl underTest = newHealthCheckerImpl(statuses.stream());
+
+    assertThat(underTest.check().getStatus())
+      .describedAs("%s should have been computed from %s statuses", RED, statuses)
+      .isEqualTo(RED);
+  }
+
+  @Test
+  public void checks_returns_causes_of_all_HealthChecks_whichever_their_status() {
+    HealthCheck[] healthChecks = IntStream.range(0, 1 + random.nextInt(20))
+      .mapToObj(s -> new StaticHealthCheck(IntStream.range(0, random.nextInt(3)).mapToObj(i -> RandomStringUtils.randomAlphanumeric(3)).toArray(String[]::new)))
+      .map(HealthCheck.class::cast)
+      .toArray(HealthCheck[]::new);
+    String[] expected = Arrays.stream(healthChecks).map(HealthCheck::check).flatMap(s -> s.getCauses().stream()).toArray(String[]::new);
+
+    HealthCheckerImpl underTest = new HealthCheckerImpl(healthChecks);
+
+    assertThat(underTest.check().getCauses()).containsOnly(expected);
+  }
+
+  private HealthCheckerImpl newHealthCheckerImpl(Stream<Health.Status> statuses) {
+    Stream<StaticHealthCheck> staticHealthCheckStream = statuses.map(StaticHealthCheck::new);
+    return new HealthCheckerImpl(staticHealthCheckStream.map(HealthCheck.class::cast).toArray(HealthCheck[]::new));
+  }
+
+  private class StaticHealthCheck implements HealthCheck {
+    private final Health health;
+
+    public StaticHealthCheck(Health.Status status) {
+      this.health = Health.newHealthCheckBuilder().setStatus(status).build();
+    }
+
+    public StaticHealthCheck(String... causes) {
+      Health.Builder builder = Health.newHealthCheckBuilder().setStatus(Health.Status.values()[random.nextInt(3)]);
+      Stream.of(causes).forEach(builder::addCause);
+      this.health = builder.build();
+    }
+
+    @Override
+    public Health check() {
+      return health;
+    }
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/HealthTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/HealthTest.java
new file mode 100644
index 00000000000..00874a89d7a
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/HealthTest.java
@@ -0,0 +1,184 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import com.google.common.base.Strings;
+import java.util.Random;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+import org.assertj.core.api.AbstractCharSequenceAssert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.apache.commons.lang.RandomStringUtils.randomAlphanumeric;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+public class HealthTest {
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private final Random random = new Random();
+  private final Health.Status anyStatus = Health.Status.values()[random.nextInt(Health.Status.values().length)];
+  private final Set<String> randomCauses = IntStream.range(0, random.nextInt(5)).mapToObj(s -> randomAlphanumeric(3)).collect(Collectors.toSet());
+
+  @Test
+  public void build_throws_NPE_if_status_is_null() {
+    Health.Builder builder = newHealthCheckBuilder();
+
+    expectStatusNotNullNPE();
+
+    builder.build();
+  }
+
+  @Test
+  public void setStatus_throws_NPE_if_status_is_null() {
+    Health.Builder builder = newHealthCheckBuilder();
+
+    expectStatusNotNullNPE();
+
+    builder.setStatus(null);
+  }
+
+  @Test
+  public void getStatus_returns_status_from_builder() {
+    Health underTest = newHealthCheckBuilder().setStatus(anyStatus).build();
+
+    assertThat(underTest.getStatus()).isEqualTo(anyStatus);
+  }
+
+  @Test
+  public void addCause_throws_NPE_if_arg_is_null() {
+    Health.Builder builder = newHealthCheckBuilder();
+
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("cause can't be null");
+
+    builder.addCause(null);
+  }
+
+  @Test
+  public void addCause_throws_IAE_if_arg_is_empty() {
+    Health.Builder builder = newHealthCheckBuilder();
+
+    expectCauseCannotBeEmptyIAE();
+
+    builder.addCause("");
+  }
+
+  @Test
+  public void addCause_throws_IAE_if_arg_contains_only_spaces() {
+    Health.Builder builder = newHealthCheckBuilder();
+
+    expectCauseCannotBeEmptyIAE();
+
+    builder.addCause(Strings.repeat(" ", 1 + random.nextInt(5)));
+  }
+
+  @Test
+  public void getCause_returns_causes_from_builder() {
+    Health.Builder builder = newHealthCheckBuilder().setStatus(anyStatus);
+    randomCauses.forEach(builder::addCause);
+    Health underTest = builder.build();
+
+    assertThat(underTest.getCauses())
+      .isEqualTo(randomCauses);
+  }
+
+  @Test
+  public void green_constant() {
+    assertThat(Health.GREEN).isEqualTo(newHealthCheckBuilder().setStatus(Health.Status.GREEN).build());
+  }
+
+  @Test
+  public void equals_is_based_on_status_and_causes() {
+    Health.Builder builder1 = newHealthCheckBuilder();
+    Health.Builder builder2 = newHealthCheckBuilder();
+
+    builder1.setStatus(anyStatus);
+    builder2.setStatus(anyStatus);
+    randomCauses.forEach(s -> {
+      builder1.addCause(s);
+      builder2.addCause(s);
+    });
+
+    assertThat(builder1.build())
+      .isEqualTo(builder1.build())
+      .isEqualTo(builder2.build())
+      .isEqualTo(builder2.build());
+  }
+
+  @Test
+  public void not_equals_to_null_nor_other_type() {
+    assertThat(Health.GREEN).isNotEqualTo(null);
+    assertThat(Health.GREEN).isNotEqualTo(new Object());
+    assertThat(Health.GREEN).isNotEqualTo(Health.Status.GREEN);
+  }
+
+  @Test
+  public void hashcode_is_based_on_status_and_causes() {
+    Health.Builder builder1 = newHealthCheckBuilder();
+    Health.Builder builder2 = newHealthCheckBuilder();
+    builder1.setStatus(anyStatus);
+    builder2.setStatus(anyStatus);
+    randomCauses.forEach(s -> {
+      builder1.addCause(s);
+      builder2.addCause(s);
+    });
+
+    assertThat(builder1.build().hashCode())
+      .isEqualTo(builder1.build().hashCode())
+      .isEqualTo(builder2.build().hashCode())
+      .isEqualTo(builder2.build().hashCode());
+  }
+
+  @Test
+  public void verify_toString() {
+    assertThat(Health.GREEN.toString()).isEqualTo("Health{GREEN, causes=[]}");
+    Health.Builder builder = newHealthCheckBuilder().setStatus(anyStatus);
+    randomCauses.forEach(builder::addCause);
+
+    String underTest = builder.build().toString();
+
+    AbstractCharSequenceAssert<?, String> a = assertThat(underTest)
+      .describedAs("toString for status %s and causes %s", anyStatus, randomCauses);
+    if (randomCauses.isEmpty()) {
+      a.isEqualTo("Health{" + anyStatus + ", causes=[]}");
+    } else if (randomCauses.size() == 1) {
+      a.isEqualTo("Health{" + anyStatus + ", causes=[" + randomCauses.iterator().next() + "]}");
+    } else {
+      a.startsWith("Health{" + anyStatus + ", causes=[")
+        .endsWith("]}")
+        .contains(randomCauses);
+    }
+  }
+
+  private void expectStatusNotNullNPE() {
+    expectedException.expect(NullPointerException.class);
+    expectedException.expectMessage("status can't be null");
+  }
+
+  private void expectCauseCannotBeEmptyIAE() {
+    expectedException.expect(IllegalArgumentException.class);
+    expectedException.expectMessage("cause can't be empty");
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/WebServerSafemodeCheckTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/WebServerSafemodeCheckTest.java
new file mode 100644
index 00000000000..255ed328bc6
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/WebServerSafemodeCheckTest.java
@@ -0,0 +1,37 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class WebServerSafemodeCheckTest {
+  private WebServerSafemodeCheck underTest = new WebServerSafemodeCheck();
+
+  @Test
+  public void always_returns_RED_status_with_cause() {
+    Health health = underTest.check();
+
+    assertThat(health.getStatus()).isEqualTo(Health.Status.RED);
+    assertThat(health.getCauses()).containsOnly("SonarQube webserver is not up");
+
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/health/WebServerStatusCheckTest.java b/server/sonar-server/src/test/java/org/sonar/server/health/WebServerStatusCheckTest.java
new file mode 100644
index 00000000000..8047c5ce3d9
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/health/WebServerStatusCheckTest.java
@@ -0,0 +1,96 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.health;
+
+import java.util.Arrays;
+import java.util.Random;
+import org.junit.Test;
+import org.sonar.server.app.RestartFlagHolder;
+import org.sonar.server.platform.Platform;
+import org.sonar.server.platform.db.migration.DatabaseMigrationState;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class WebServerStatusCheckTest {
+  private final DatabaseMigrationState migrationState = mock(DatabaseMigrationState.class);
+  private final Platform platform = mock(Platform.class);
+  private final RestartFlagHolder restartFlagHolder = mock(RestartFlagHolder.class);
+
+  private final Random random = new Random();
+
+  private WebServerStatusCheck underTest = new WebServerStatusCheck(migrationState, platform, restartFlagHolder);
+
+  @Test
+  public void returns_RED_status_with_cause_if_platform_status_is_not_UP() {
+    Platform.Status[] statusesButUp = Arrays.stream(Platform.Status.values())
+      .filter(s -> s != Platform.Status.UP)
+      .toArray(Platform.Status[]::new);
+    Platform.Status randomStatusButUp = statusesButUp[random.nextInt(statusesButUp.length)];
+    when(platform.status()).thenReturn(randomStatusButUp);
+
+    Health health = underTest.check();
+
+    verifyRedHealthWithCause(health);
+  }
+
+  @Test
+  public void returns_RED_status_with_cause_if_platform_status_is_UP_but_migrationStatus_is_neither_NONE_nor_SUCCEED() {
+    when(platform.status()).thenReturn(Platform.Status.UP);
+    DatabaseMigrationState.Status[] statusesButValidOnes = Arrays.stream(DatabaseMigrationState.Status.values())
+      .filter(s -> s != DatabaseMigrationState.Status.NONE)
+      .filter(s -> s != DatabaseMigrationState.Status.SUCCEEDED)
+      .toArray(DatabaseMigrationState.Status[]::new);
+    DatabaseMigrationState.Status randomInvalidStatus = statusesButValidOnes[random.nextInt(statusesButValidOnes.length)];
+    when(migrationState.getStatus()).thenReturn(randomInvalidStatus);
+
+    Health health = underTest.check();
+
+    verifyRedHealthWithCause(health);
+  }
+
+  @Test
+  public void returns_RED_with_cause_if_platform_status_is_UP_migration_status_is_valid_but_SQ_is_restarting() {
+    when(platform.status()).thenReturn(Platform.Status.UP);
+    when(migrationState.getStatus()).thenReturn(random.nextBoolean() ? DatabaseMigrationState.Status.NONE : DatabaseMigrationState.Status.SUCCEEDED);
+    when(restartFlagHolder.isRestarting()).thenReturn(true);
+
+    Health health = underTest.check();
+
+    verifyRedHealthWithCause(health);
+  }
+
+  @Test
+  public void returns_GREEN_without_cause_if_platform_status_is_UP_migration_status_is_valid_and_SQ_is_not_restarting() {
+    when(platform.status()).thenReturn(Platform.Status.UP);
+    when(migrationState.getStatus()).thenReturn(random.nextBoolean() ? DatabaseMigrationState.Status.NONE : DatabaseMigrationState.Status.SUCCEEDED);
+    when(restartFlagHolder.isRestarting()).thenReturn(false);
+
+    Health health = underTest.check();
+
+    assertThat(health).isEqualTo(Health.GREEN);
+  }
+
+  private void verifyRedHealthWithCause(Health health) {
+    assertThat(health.getStatus()).isEqualTo(Health.Status.RED);
+    assertThat(health.getCauses()).containsOnly("SonarQube webserver is not up");
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/platform/ws/AbstractHealthActionTestSupport.java b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/AbstractHealthActionTestSupport.java
new file mode 100644
index 00000000000..91985e5f063
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/AbstractHealthActionTestSupport.java
@@ -0,0 +1,76 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import java.util.Random;
+import java.util.stream.IntStream;
+import org.apache.commons.lang.RandomStringUtils;
+import org.sonar.api.server.ws.WebService;
+import org.sonar.server.health.Health;
+import org.sonar.server.health.HealthChecker;
+import org.sonar.server.ws.TestRequest;
+import org.sonar.server.ws.WsActionTester;
+import org.sonar.test.JsonAssert;
+import org.sonarqube.ws.WsSystem;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.sonar.server.health.Health.newHealthCheckBuilder;
+
+public class AbstractHealthActionTestSupport {
+  HealthChecker mockedHealthChecker = mock(HealthChecker.class);
+
+  void verifyDefinition(WebService.Action definition) {
+    assertThat(definition.key()).isEqualTo("health");
+    assertThat(definition.isPost()).isFalse();
+    assertThat(definition.description()).isNotEmpty();
+    assertThat(definition.since()).isEqualTo("6.6");
+    assertThat(definition.isInternal()).isFalse();
+    assertThat(definition.responseExample()).isNotNull();
+    assertThat(definition.params()).isEmpty();
+  }
+
+  void verifyExample(WsActionTester underTest) {
+    when(mockedHealthChecker.check()).thenReturn(
+        newHealthCheckBuilder()
+            .setStatus(Health.Status.YELLOW)
+            .addCause("Elasticsearch status is YELLOW")
+            .build());
+    TestRequest request = underTest.newRequest();
+
+    JsonAssert.assertJson(request.execute().getInput())
+        .isSimilarTo(underTest.getDef().responseExampleAsString());
+  }
+
+  void requestReturnsStatusAndCausesFromHealthCheckerCheckMethod(WsActionTester underTest) {
+    Health.Status randomStatus = Health.Status.values()[new Random().nextInt(Health.Status.values().length)];
+    Health.Builder builder = newHealthCheckBuilder()
+        .setStatus(randomStatus);
+    IntStream.range(0, new Random().nextInt(5)).mapToObj(i -> RandomStringUtils.randomAlphanumeric(3)).forEach(builder::addCause);
+    Health health = builder.build();
+    when(mockedHealthChecker.check()).thenReturn(health);
+    TestRequest request = underTest.newRequest();
+
+    WsSystem.HealthResponse healthResponse = request.executeProtobuf(WsSystem.HealthResponse.class);
+    assertThat(healthResponse.getHealth().name()).isEqualTo(randomStatus.name());
+    assertThat(health.getCauses()).isEqualTo(health.getCauses());
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionModuleTest.java b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionModuleTest.java
new file mode 100644
index 00000000000..32d54bf4b1c
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionModuleTest.java
@@ -0,0 +1,69 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.junit.Test;
+import org.picocontainer.ComponentAdapter;
+import org.sonar.core.platform.ComponentContainer;
+import org.sonar.server.health.DbConnectionCheck;
+import org.sonar.server.health.EsStatusCheck;
+import org.sonar.server.health.HealthCheck;
+import org.sonar.server.health.HealthCheckerImpl;
+import org.sonar.server.health.WebServerStatusCheck;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class HealthActionModuleTest {
+  private HealthActionModule underTest = new HealthActionModule();
+
+  @Test
+  public void verify_action_and_HealthChecker() {
+    ComponentContainer container = new ComponentContainer();
+
+    underTest.configure(container);
+
+    assertThat(classesAddedToContainer(container))
+        .contains(HealthCheckerImpl.class)
+        .contains(HealthAction.class)
+        .doesNotContain(SafeModeHealthAction.class);
+  }
+
+  @Test
+  public void verify_installed_HealthChecks_implementations() {
+    ComponentContainer container = new ComponentContainer();
+
+    underTest.configure(container);
+
+    List<Class<?>> checks = classesAddedToContainer(container).stream().filter(HealthCheck.class::isAssignableFrom).collect(Collectors.toList());
+    assertThat(checks)
+      .hasSize(3)
+      .contains(WebServerStatusCheck.class)
+      .contains(DbConnectionCheck.class)
+      .contains(EsStatusCheck.class);
+  }
+
+  private List<Class<?>> classesAddedToContainer(ComponentContainer container) {
+    Collection<ComponentAdapter<?>> componentAdapters = container.getPicoContainer().getComponentAdapters();
+    return componentAdapters.stream().map(ComponentAdapter::getComponentImplementation).collect(Collectors.toList());
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionTest.java b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionTest.java
new file mode 100644
index 00000000000..201b34fd328
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/HealthActionTest.java
@@ -0,0 +1,93 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import java.util.Random;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.sonar.api.server.ws.WebService;
+import org.sonar.server.exceptions.ForbiddenException;
+import org.sonar.server.exceptions.UnauthorizedException;
+import org.sonar.server.tester.UserSessionRule;
+import org.sonar.server.ws.TestRequest;
+import org.sonar.server.ws.WsActionTester;
+
+public class HealthActionTest {
+  @Rule
+  public UserSessionRule userSessionRule = UserSessionRule.standalone();
+  @Rule
+  public ExpectedException expectedException = ExpectedException.none();
+
+  private AbstractHealthActionTestSupport healthActionTestSupport = new AbstractHealthActionTestSupport();
+  private WsActionTester underTest = new WsActionTester(new HealthAction(userSessionRule, healthActionTestSupport.mockedHealthChecker));
+
+  @Test
+  public void verify_definition() {
+    WebService.Action definition = underTest.getDef();
+
+    healthActionTestSupport.verifyDefinition(definition);
+  }
+
+  @Test
+  public void execute_fails_with_UnauthorizedException_if_user_is_not_logged_in() {
+    TestRequest request = underTest.newRequest();
+
+    expectedException.expect(UnauthorizedException.class);
+    expectedException.expectMessage("Authentication is required");
+
+    request.execute();
+  }
+
+  @Test
+  public void execute_fails_with_ForbiddenException_if_user_logged_in_but_not_root() {
+    TestRequest request = underTest.newRequest();
+    userSessionRule.logIn();
+
+    expectedException.expect(ForbiddenException.class);
+    expectedException.expectMessage("Insufficient privileges");
+
+    request.execute();
+  }
+
+  @Test
+  public void verify_example() {
+    userSessionRule.logIn();
+    rootOrSystemAdmin();
+
+    healthActionTestSupport.verifyExample(underTest);
+  }
+
+  @Test
+  public void request_returns_status_and_causes_from_HealthChecker_check_method() {
+    userSessionRule.logIn();
+    rootOrSystemAdmin();
+
+    healthActionTestSupport.requestReturnsStatusAndCausesFromHealthCheckerCheckMethod(underTest);
+  }
+
+  private void rootOrSystemAdmin() {
+    if (new Random().nextBoolean()) {
+      userSessionRule.setRoot();
+    } else {
+      userSessionRule.setSystemAdministrator();
+    }
+  }
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionModuleTest.java b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionModuleTest.java
new file mode 100644
index 00000000000..f99fa201a33
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionModuleTest.java
@@ -0,0 +1,70 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.junit.Test;
+import org.picocontainer.ComponentAdapter;
+import org.sonar.core.platform.ComponentContainer;
+import org.sonar.server.health.DbConnectionCheck;
+import org.sonar.server.health.EsStatusCheck;
+import org.sonar.server.health.HealthCheck;
+import org.sonar.server.health.HealthCheckerImpl;
+import org.sonar.server.health.WebServerSafemodeCheck;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class SafeModeHealthActionModuleTest {
+  private SafeModeHealthActionModule underTest = new SafeModeHealthActionModule();
+
+  @Test
+  public void verify_action_and_HealthChecker() {
+    ComponentContainer container = new ComponentContainer();
+
+    underTest.configure(container);
+
+    assertThat(classesAddedToContainer(container))
+      .contains(HealthCheckerImpl.class)
+      .contains(SafeModeHealthAction.class)
+      .doesNotContain(HealthAction.class);
+  }
+
+  @Test
+  public void verify_installed_HealthChecks_implementations() {
+    ComponentContainer container = new ComponentContainer();
+
+    underTest.configure(container);
+
+    List<Class<?>> checks = classesAddedToContainer(container).stream().filter(HealthCheck.class::isAssignableFrom).collect(Collectors.toList());
+    assertThat(checks)
+      .hasSize(3)
+      .contains(WebServerSafemodeCheck.class)
+      .contains(DbConnectionCheck.class)
+      .contains(EsStatusCheck.class);
+  }
+
+  private List<Class<?>> classesAddedToContainer(ComponentContainer container) {
+    Collection<ComponentAdapter<?>> componentAdapters = container.getPicoContainer().getComponentAdapters();
+    return componentAdapters.stream().map(ComponentAdapter::getComponentImplementation).collect(Collectors.toList());
+  }
+
+}
diff --git a/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionTest.java b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionTest.java
new file mode 100644
index 00000000000..0cec5200305
--- /dev/null
+++ b/server/sonar-server/src/test/java/org/sonar/server/platform/ws/SafeModeHealthActionTest.java
@@ -0,0 +1,47 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2017 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.platform.ws;
+
+import org.junit.Test;
+import org.sonar.api.server.ws.WebService;
+import org.sonar.server.ws.WsActionTester;
+
+public class SafeModeHealthActionTest {
+  private AbstractHealthActionTestSupport healthActionTestSupport = new AbstractHealthActionTestSupport();
+  private WsActionTester underTest = new WsActionTester(new SafeModeHealthAction(healthActionTestSupport.mockedHealthChecker));
+
+  @Test
+  public void verify_definition() {
+    WebService.Action definition = underTest.getDef();
+
+    healthActionTestSupport.verifyDefinition(definition);
+  }
+
+  @Test
+  public void verify_example() {
+    healthActionTestSupport.verifyExample(underTest);
+  }
+
+  @Test
+  public void request_returns_status_and_causes_from_HealthChecker_check_method() {
+    healthActionTestSupport.requestReturnsStatusAndCausesFromHealthCheckerCheckMethod(underTest);
+  }
+
+}
diff --git a/sonar-ws/src/main/protobuf/ws-system.proto b/sonar-ws/src/main/protobuf/ws-system.proto
new file mode 100644
index 00000000000..4f0fd9af5fc
--- /dev/null
+++ b/sonar-ws/src/main/protobuf/ws-system.proto
@@ -0,0 +1,41 @@
+// SonarQube, open source software quality management tool.
+// Copyright (C) 2008-2016 SonarSource
+// mailto:contact AT sonarsource DOT com
+//
+// SonarQube is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 3 of the License, or (at your option) any later version.
+//
+// SonarQube is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program; if not, write to the Free Software Foundation,
+// Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+syntax = "proto2";
+
+package sonarqube.ws.system;
+
+option java_package = "org.sonarqube.ws";
+option java_outer_classname = "WsSystem";
+option optimize_for = SPEED;
+
+// GET api/system/health
+message HealthResponse {
+  optional Health health = 1;
+  repeated Cause causes = 2;
+}
+
+message Cause {
+  optional string message = 1;
+}
+
+enum Health {
+  GREEN = 0;
+  YELLOW = 1;
+  RED = 2;
+}