Refactor path & config system (#25330)

# The problem

There were many "path tricks":

* By default, Gitea uses its program directory as its work path
* Gitea tries to use the "work path" to guess its "custom path" and
"custom conf (app.ini)"
* Users might want to use other directories as work path
* The non-default work path should be passed to Gitea by GITEA_WORK_DIR
or "--work-path"
* But some Gitea processes are started without these values
    * The "serv" process started by OpenSSH server
    * The CLI sub-commands started by site admin
* The paths are guessed by SetCustomPathAndConf again and again
* The default values of "work path / custom path / custom conf" can be
changed when compiling

# The solution

* Use `InitWorkPathAndCommonConfig` to handle these path tricks, and use
test code to cover its behaviors.
* When Gitea's web server runs, write the WORK_PATH to "app.ini", this
value must be the most correct one, because if this value is not right,
users would find that the web UI doesn't work and then they should be
able to fix it.
* Then all other sub-commands can use the WORK_PATH in app.ini to
initialize their paths.
* By the way, when Gitea starts for git protocol, it shouldn't output
any log, otherwise the git protocol gets broken and client blocks
forever.

The "work path" priority is: WORK_PATH in app.ini > cmd arg --work-path
> env var GITEA_WORK_DIR > builtin default

The "app.ini" searching order is: cmd arg --config > cmd arg "work path
/ custom path" > env var "work path / custom path" > builtin default


## ⚠️ BREAKING

If your instance's "work path / custom path / custom conf" doesn't meet
the requirements (eg: work path must be absolute), Gitea will report a
fatal error and exit. You need to set these values according to the
error log.



----

Close #24818
Close #24222
Close #21606
Close #21498
Close #25107
Close #24981
Maybe close #24503

Replace #23301
Replace #22754

And maybe more

2 files changed, 14 insertions, 57 deletions

diff --git a/routers/install/install.go b/routers/install/install.go
index 16bb55b685..c94a30b89f 100644
--- a/routers/install/install.go
+++ b/routers/install/install.go
@@ -32,6 +32,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
 	"code.gitea.io/gitea/modules/web/middleware"
+	"code.gitea.io/gitea/routers/common"
 	"code.gitea.io/gitea/services/forms"
 
 	"gitea.com/go-chi/session"
@@ -370,11 +371,16 @@ func SubmitInstall(ctx *context.Context) {
 	}
 
 	// Save settings.
-	cfg, err := setting.NewConfigProviderFromFile(&setting.Options{CustomConf: setting.CustomConf, AllowEmpty: true})
+	cfg, err := setting.NewConfigProviderFromFile(setting.CustomConf)
 	if err != nil {
 		log.Error("Failed to load custom conf '%s': %v", setting.CustomConf, err)
 	}
 
+	cfg.Section("").Key("APP_NAME").SetValue(form.AppName)
+	cfg.Section("").Key("RUN_USER").SetValue(form.RunUser)
+	cfg.Section("").Key("WORK_PATH").SetValue(setting.AppWorkPath)
+	cfg.Section("").Key("RUN_MODE").SetValue("prod")
+
 	cfg.Section("database").Key("DB_TYPE").SetValue(setting.Database.Type.String())
 	cfg.Section("database").Key("HOST").SetValue(setting.Database.Host)
 	cfg.Section("database").Key("NAME").SetValue(setting.Database.Name)
@@ -386,9 +392,7 @@ func SubmitInstall(ctx *context.Context) {
 	cfg.Section("database").Key("PATH").SetValue(setting.Database.Path)
 	cfg.Section("database").Key("LOG_SQL").SetValue("false") // LOG_SQL is rarely helpful
 
-	cfg.Section("").Key("APP_NAME").SetValue(form.AppName)
 	cfg.Section("repository").Key("ROOT").SetValue(form.RepoRootPath)
-	cfg.Section("").Key("RUN_USER").SetValue(form.RunUser)
 	cfg.Section("server").Key("SSH_DOMAIN").SetValue(form.Domain)
 	cfg.Section("server").Key("DOMAIN").SetValue(form.Domain)
 	cfg.Section("server").Key("HTTP_PORT").SetValue(form.HTTPPort)
@@ -450,8 +454,6 @@ func SubmitInstall(ctx *context.Context) {
 	cfg.Section("service").Key("NO_REPLY_ADDRESS").SetValue(fmt.Sprint(form.NoReplyAddress))
 	cfg.Section("cron.update_checker").Key("ENABLED").SetValue(fmt.Sprint(form.EnableUpdateChecker))
 
-	cfg.Section("").Key("RUN_MODE").SetValue("prod")
-
 	cfg.Section("session").Key("PROVIDER").SetValue("file")
 
 	cfg.Section("log").Key("MODE").MustString("console")
@@ -514,7 +516,13 @@ func SubmitInstall(ctx *context.Context) {
 	// ---- All checks are passed
 
 	// Reload settings (and re-initialize database connection)
-	reloadSettings(ctx)
+	setting.InitCfgProvider(setting.CustomConf)
+	setting.LoadCommonSettings()
+	setting.MustInstalled()
+	setting.LoadDBSetting()
+	if err := common.InitDBEngine(ctx); err != nil {
+		log.Fatal("ORM engine initialization failed: %v", err)
+	}
 
 	// Create admin account
 	if len(form.AdminName) > 0 {
diff --git a/routers/install/setting.go b/routers/install/setting.go
deleted file mode 100644
index c14843d8ee..0000000000
--- a/routers/install/setting.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2021 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-package install
-
-import (
-	"context"
-
-	"code.gitea.io/gitea/modules/log"
-	"code.gitea.io/gitea/modules/setting"
-	"code.gitea.io/gitea/modules/svg"
-	"code.gitea.io/gitea/modules/translation"
-	"code.gitea.io/gitea/routers/common"
-)
-
-// PreloadSettings preloads the configuration to check if we need to run install
-func PreloadSettings(ctx context.Context) bool {
-	setting.Init(&setting.Options{
-		AllowEmpty: true,
-	})
-	if !setting.InstallLock {
-		log.Info("AppPath: %s", setting.AppPath)
-		log.Info("AppWorkPath: %s", setting.AppWorkPath)
-		log.Info("Custom path: %s", setting.CustomPath)
-		log.Info("Log path: %s", setting.Log.RootPath)
-		log.Info("Configuration file: %s", setting.CustomConf)
-		log.Info("Prepare to run install page")
-		translation.InitLocales(ctx)
-		if setting.EnableSQLite3 {
-			log.Info("SQLite3 is supported")
-		}
-
-		setting.LoadSettingsForInstall()
-		_ = svg.Init()
-	}
-
-	return !setting.InstallLock
-}
-
-// reloadSettings reloads the existing settings and starts up the database
-func reloadSettings(ctx context.Context) {
-	setting.Init(&setting.Options{})
-	setting.LoadDBSetting()
-	if setting.InstallLock {
-		if err := common.InitDBEngine(ctx); err == nil {
-			log.Info("ORM engine initialization successful!")
-		} else {
-			log.Fatal("ORM engine initialization failed: %v", err)
-		}
-	}
-}