yml-config: Add support of rootUser and rootPassword (#18615)

Users can define the root user and password in the yaml configuration
file; Root credentials defined in the environment variable still take
precedence

cmd/server-main.go

@@ -248,6 +248,10 @@ func mergeServerCtxtFromConfigFile(configFile string, ctxt *serverCtxt) error {
 	if cf.Version != "v1" {
 		return fmt.Errorf("unexpected version: %s", cf.Version)
 	}
+
+	ctxt.RootUser = cf.RootUser
+	ctxt.RootPwd = cf.RootPwd
+
 	if cf.Addr != "" {
 		ctxt.Addr = cf.Addr
 	}
@@ -353,11 +357,6 @@ func serverHandleCmdArgs(ctxt serverCtxt) {
 	globalConnWriteDeadline = ctxt.ConnWriteDeadline
 }
 
-func serverHandleEnvVars() {
-	// Handle common environment variables.
-	handleCommonEnvVars()
-}
-
 var globalHealStateLK sync.RWMutex
 
 func initAllSubsystems(ctx context.Context) {
@@ -654,6 +653,10 @@ func serverMain(ctx *cli.Context) {
 	// Handle all server environment vars.
 	serverHandleEnvVars()
 
+	// Load the root credentials from the shell environment or from
+	// the config file if not defined, set the default one.
+	loadRootCredentials()
+
 	// Initialize globalConsoleSys system
 	bootstrapTrace("newConsoleLogger", func() {
 		globalConsoleSys = NewConsoleLogger(GlobalContext)