Add a new command doctor to check if some wrong configurations on gitea instance (#9095)

* add doctor

* Add a new command doctor to check if some wrong configurations on gitea instance

* fix import

* use regex match authorized_keys on doctor

* Add documentation

3 files changed, 156 insertions, 0 deletions

diff --git a/cmd/doctor.go b/cmd/doctor.go
new file mode 100644
index 0000000000..d81ead97c7
--- /dev/null
+++ b/cmd/doctor.go
@@ -0,0 +1,130 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package cmd
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/urfave/cli"
+)
+
+// CmdDoctor represents the available doctor sub-command.
+var CmdDoctor = cli.Command{
+	Name:        "doctor",
+	Usage:       "Diagnose the problems",
+	Description: "A command to diagnose the problems of current gitea instance according the given configuration.",
+	Action:      runDoctor,
+}
+
+type check struct {
+	title string
+	f     func(ctx *cli.Context) ([]string, error)
+}
+
+// checklist represents list for all checks
+var checklist = []check{
+	{
+		title: "Check if OpenSSH authorized_keys file id correct",
+		f:     runDoctorLocationMoved,
+	},
+	// more checks please append here
+}
+
+func runDoctor(ctx *cli.Context) error {
+	err := initDB()
+	fmt.Println("Using app.ini at", setting.CustomConf)
+	if err != nil {
+		fmt.Println(err)
+		fmt.Println("Check if you are using the right config file. You can use a --config directive to specify one.")
+		return nil
+	}
+
+	for i, check := range checklist {
+		fmt.Println("[", i+1, "]", check.title)
+		if messages, err := check.f(ctx); err != nil {
+			fmt.Println("Error:", err)
+		} else if len(messages) > 0 {
+			for _, message := range messages {
+				fmt.Println("-", message)
+			}
+		} else {
+			fmt.Println("OK.")
+		}
+		fmt.Println()
+	}
+	return nil
+}
+
+func exePath() (string, error) {
+	file, err := exec.LookPath(os.Args[0])
+	if err != nil {
+		return "", err
+	}
+	return filepath.Abs(file)
+}
+
+func runDoctorLocationMoved(ctx *cli.Context) ([]string, error) {
+	if setting.SSH.StartBuiltinServer || !setting.SSH.CreateAuthorizedKeysFile {
+		return nil, nil
+	}
+
+	fPath := filepath.Join(setting.SSH.RootPath, "authorized_keys")
+	f, err := os.Open(fPath)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	var firstline string
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		firstline = strings.TrimSpace(scanner.Text())
+		if len(firstline) == 0 || firstline[0] == '#' {
+			continue
+		}
+		break
+	}
+
+	// command="/Volumes/data/Projects/gitea/gitea/gitea --config
+	if len(firstline) > 0 {
+		exp := regexp.MustCompile(`^[ \t]*(?:command=")([^ ]+) --config='([^']+)' serv key-([^"]+)",(?:[^ ]+) ssh-rsa ([^ ]+) ([^ ]+)[ \t]*$`)
+
+		// command="/home/user/gitea --config='/home/user/etc/app.ini' serv key-999",option-1,option-2,option-n ssh-rsa public-key-value key-name
+		res := exp.FindStringSubmatch(firstline)
+		if res == nil {
+			return nil, errors.New("Unknow authorized_keys format")
+		}
+
+		giteaPath := res[1] // => /home/user/gitea
+		iniPath := res[2]   // => /home/user/etc/app.ini
+
+		p, err := exePath()
+		if err != nil {
+			return nil, err
+		}
+		p, err = filepath.Abs(p)
+		if err != nil {
+			return nil, err
+		}
+
+		if len(giteaPath) > 0 && giteaPath != p {
+			return []string{fmt.Sprintf("Gitea exe path wants %s but %s on %s", p, giteaPath, fPath)}, nil
+		}
+		if len(iniPath) > 0 && iniPath != setting.CustomConf {
+			return []string{fmt.Sprintf("Gitea config path wants %s but %s on %s", setting.CustomConf, iniPath, fPath)}, nil
+		}
+	}
+
+	return nil, nil
+}
diff --git a/docs/content/doc/usage/command-line.en-us.md b/docs/content/doc/usage/command-line.en-us.md
index 0f7b4f61a2..60c2e26a7b 100644
--- a/docs/content/doc/usage/command-line.en-us.md
+++ b/docs/content/doc/usage/command-line.en-us.md
@@ -289,3 +289,28 @@ This command is idempotent.
 
 #### convert
 Converts an existing MySQL database from utf8 to utf8mb4.
+
+#### doctor
+Diagnose the problems of current gitea instance according the given configuration.
+Currently there are a check list below:
+
+- Check if OpenSSH authorized_keys file id correct
+When your gitea instance support OpenSSH, your gitea instance binary path will be written to `authorized_keys` 
+when there is any public key added or changed on your gitea instance.
+Sometimes if you moved or renamed your gitea binary when upgrade and you haven't run `Update the '.ssh/authorized_keys' file with Gitea SSH keys. (Not needed for the built-in SSH server.)` on your Admin Panel. Then all pull/push via SSH will not be work.
+This check will help you to check if it works well.
+
+For contributors, if you want to add more checks, you can wrie ad new function like `func(ctx *cli.Context) ([]string, error)` and 
+append it to `doctor.go`.
+
+```go
+var checklist = []check{
+	{
+		title: "Check if OpenSSH authorized_keys file id correct",
+		f:     runDoctorLocationMoved,
+    },
+    // more checks please append here
+}
+```
+
+This function will receive a command line context and return a list of details about the problems or error.
\ No newline at end of file
diff --git a/main.go b/main.go
index 30dbf27662..c67eaf7692 100644
--- a/main.go
+++ b/main.go
@@ -68,6 +68,7 @@ arguments - which can alternatively be run by running the subcommand web.`
 		cmd.CmdMigrate,
 		cmd.CmdKeys,
 		cmd.CmdConvert,
+		cmd.CmdDoctor,
 	}
 	// Now adjust these commands to add our global configuration options