Vault-4279 reporting redundant/unused keys in config (#14752)

* Vault-4279 reporting redundant/unused keys in config

* missing validate step

* CL

* Change the log level

changelog/14752.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+core: report unused or redundant keys in server configuration   
+```

command/server.go

@@ -427,7 +427,7 @@ func (c *ServerCommand) parseConfig() (*server.Config, []configutil.ConfigError,
 }
 
 func (c *ServerCommand) runRecoveryMode() int {
-	config, _, err := c.parseConfig()
+	config, configErrors, err := c.parseConfig()
 	if err != nil {
 		c.UI.Error(err.Error())
 		return 1
@@ -457,6 +457,11 @@ func (c *ServerCommand) runRecoveryMode() int {
 		JSONFormat: logFormat == logging.JSONFormat,
 	})
 
+	// reporting Errors found in the config
+	for _, cErr := range configErrors {
+		c.logger.Warn(cErr.String())
+	}
+
 	// Ensure logging is flushed if initialization fails
 	defer c.flushLog()
 
@@ -1066,7 +1071,7 @@ func (c *ServerCommand) Run(args []string) int {
 		config.Listeners[0].Telemetry.UnauthenticatedMetricsAccess = true
 	}
 
-	parsedConfig, _, err := c.parseConfig()
+	parsedConfig, configErrors, err := c.parseConfig()
 	if err != nil {
 		c.UI.Error(err.Error())
 		return 1
@@ -1111,6 +1116,11 @@ func (c *ServerCommand) Run(args []string) int {
 		})
 	}
 
+	// reporting Errors found in the config
+	for _, cErr := range configErrors {
+		c.logger.Warn(cErr.String())
+	}
+
 	// Ensure logging is flushed if initialization fails
 	defer c.flushLog()
 
@@ -1213,7 +1223,6 @@ func (c *ServerCommand) Run(args []string) int {
 	info["log level"] = logLevelString
 	infoKeys = append(infoKeys, "log level")
 	barrierSeal, barrierWrapper, unwrapSeal, seals, sealConfigError, err := setSeal(c, config, infoKeys, info)
-
 	// Check error here
 	if err != nil {
 		c.UI.Error(err.Error())
@@ -1520,13 +1529,16 @@ func (c *ServerCommand) Run(args []string) int {
 			// Check for new log level
 			var config *server.Config
 			var level log.Level
+			var configErrors []configutil.ConfigError
 			for _, path := range c.flagConfigs {
 				current, err := server.LoadConfig(path)
 				if err != nil {
 					c.logger.Error("could not reload config", "path", path, "error", err)
 					goto RUNRELOADFUNCS
 				}
 
+				configErrors = append(configErrors, current.Validate(path)...)
+
 				if config == nil {
 					config = current
 				} else {
@@ -1540,6 +1552,11 @@ func (c *ServerCommand) Run(args []string) int {
 				goto RUNRELOADFUNCS
 			}
 
+			// reporting Errors found in the config
+			for _, cErr := range configErrors {
+				c.logger.Warn(cErr.String())
+			}
+
 			core.SetConfig(config)
 
 			if config.LogLevel != "" {