Backport of fix: Make agent syslog log level inherit from Nomad agent…

… log into release/1.3.x (#15688)

This pull request was automerged via backport-assistant

.changelog/15625.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+agent: Make agent syslog log level follow log_level config
+```

command/agent/command.go

@@ -472,10 +472,21 @@ func SetupLoggers(ui cli.Ui, config *Config) (*logutils.LevelFilter, *gatedwrite
 
 	// Create a log writer, and wrap a logOutput around it
 	writers := []io.Writer{logFilter}
-
+	logLevel := strings.ToUpper(config.LogLevel)
+	logLevelMap := map[string]gsyslog.Priority{
+		"ERROR": gsyslog.LOG_ERR,
+		"WARN":  gsyslog.LOG_WARNING,
+		"INFO":  gsyslog.LOG_INFO,
+		"DEBUG": gsyslog.LOG_DEBUG,
+		"TRACE": gsyslog.LOG_DEBUG,
+	}
+	if logLevel == "OFF" {
+		config.EnableSyslog = false
+	}
 	// Check if syslog is enabled
 	if config.EnableSyslog {
-		l, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, config.SyslogFacility, "nomad")
+		ui.Output(fmt.Sprintf("Config enable_syslog is `true` with log_level=%v", config.LogLevel))
+		l, err := gsyslog.NewLogger(logLevelMap[logLevel], config.SyslogFacility, "nomad")
 		if err != nil {
 			ui.Error(fmt.Sprintf("Syslog setup failed: %v", err))
 			return nil, nil, nil

website/content/docs/configuration/index.mdx

@@ -166,7 +166,8 @@ testing.
   diagnostic information about Nomad's internals.
 
 - `enable_syslog` `(bool: false)` - Specifies if the agent should log to syslog.
-  This option only works on Unix based systems.
+  This option only works on Unix based systems. The log level inherits from
+  the Nomad agent log set in `log_level`
 
 - `http_api_response_headers` `(map<string|string>: nil)` - Specifies
   user-defined headers to add to the HTTP API responses.