Database: Adds support for enable/disable SQLite Write-Ahead Logging …

…(WAL) via configuration (grafana#58268)

Adds support for enable/disable SQLite Write-Ahead Logging (WAL) via configuration.
Enables SQLite WAL for E2E tests.

conf/defaults.ini

@@ -134,6 +134,9 @@ path = grafana.db
 # For "sqlite3" only. cache mode setting used for connecting to the database
 cache_mode = private
 
+# For "sqlite3" only. Enable/disable Write-Ahead Logging, https://sqlite.org/wal.html. Default is false.
+wal = false
+
 # For "mysql" only if migrationLocking feature toggle is set. How many seconds to wait before failing to lock the database for the migrations, default is 0.
 locking_attempt_timeout_sec = 0
 
@@ -1147,7 +1150,7 @@ renderer_token = -
 # which this setting can help protect against by only allowing a certain amount of concurrent requests.
 concurrent_render_request_limit = 30
 # Determines the lifetime of the render key used by the image renderer to access and render Grafana.
-# This setting should be expressed as a duration. Examples: 10s (seconds), 5m (minutes), 2h (hours). 
+# This setting should be expressed as a duration. Examples: 10s (seconds), 5m (minutes), 2h (hours).
 # Default is 5m. This should be more than enough for most deployments.
 # Change the value only if image rendering is failing and you see `Failed to get the render key from cache` in Grafana logs.
 render_key_lifetime = 5m

conf/sample.ini

@@ -136,6 +136,9 @@
 # For "sqlite3" only. cache mode setting used for connecting to the database. (private, shared)
 ;cache_mode = private
 
+# For "sqlite3" only. Enable/disable Write-Ahead Logging, https://sqlite.org/wal.html. Default is false.
+;wal = false
+
 # For "mysql" only if migrationLocking feature toggle is set. How many seconds to wait before failing to lock the database for the migrations, default is 0.
 ;locking_attempt_timeout_sec = 0
 

docs/sources/setup-grafana/configure-grafana/_index.md

@@ -380,6 +380,10 @@ will be stored.
 For "sqlite3" only. [Shared cache](https://www.sqlite.org/sharedcache.html) setting used for connecting to the database. (private, shared)
 Defaults to `private`.
 
+### wal
+
+For "sqlite3" only. Setting to enable/disable [Write-Ahead Logging](https://sqlite.org/wal.html). The default value is `false` (disabled).
+
 ### query_retries
 
 This setting applies to `sqlite` only and controls the number of times the system retries a query when the database is locked. The default value is `0` (disabled).

pkg/services/sqlstore/sqlstore.go

@@ -325,6 +325,11 @@ func (ss *SQLStore) buildConnectionString() (string, error) {
 		}
 
 		cnnstr = fmt.Sprintf("file:%s?cache=%s&mode=rwc", ss.dbCfg.Path, ss.dbCfg.CacheMode)
+
+		if ss.dbCfg.WALEnabled {
+			cnnstr += "&_journal_mode=WAL"
+		}
+
 		cnnstr += ss.buildExtraConnectionString('&')
 	default:
 		return "", fmt.Errorf("unknown database type: %s", ss.dbCfg.Type)
@@ -453,6 +458,7 @@ func (ss *SQLStore) readConfig() error {
 	ss.dbCfg.IsolationLevel = sec.Key("isolation_level").String()
 
 	ss.dbCfg.CacheMode = sec.Key("cache_mode").MustString("private")
+	ss.dbCfg.WALEnabled = sec.Key("wal").MustBool(false)
 	ss.dbCfg.SkipMigrations = sec.Key("skip_migrations").MustBool()
 	ss.dbCfg.MigrationLockAttemptTimeout = sec.Key("locking_attempt_timeout_sec").MustInt()
 
@@ -677,6 +683,7 @@ type DatabaseConfig struct {
 	MaxIdleConn                 int
 	ConnMaxLifetime             int
 	CacheMode                   string
+	WALEnabled                  bool
 	UrlQueryParams              map[string][]string
 	SkipMigrations              bool
 	MigrationLockAttemptTimeout int

scripts/grafana-server/custom.ini

@@ -1,2 +1,6 @@
 [feature_toggles]
 enable = publicDashboards
+
+[database]
+type=sqlite3
+wal=true