feat: add log levels to frontend

hsmatulis · bwplotka · commit ea0e58aa2937 · 2024-10-31T18:14:23.000+01:00
Signed-off-by: Henrique Spanoudis Matulis &lt;hmatulis@google.com&gt;
diff --git a/cmd/frontend/main.go b/cmd/frontend/main.go
@@ -67,6 +67,9 @@ var (
 		fmt.Sprintf("The URL to forward authenticated requests to. (%s is replaced with the --query.project-id flag.)", projectIDVar))
 
 	ruleEndpointURLStrings = flag.String("rules.target-urls", "http://rule-evaluator.gmp-system.svc.cluster.local:19092", "Comma separated lists of URLs that support HTTP Prometheus Alert and Rules APIs (/api/v1/alerts, /api/v1/rules), e.g. GMP rule-evaluator. NOTE: Results are merged as-is, no sorting and deduplication is done.")
+
+	logLevel = flag.String("log.level", "info",
+		"The level of logging. Can be one of 'debug', 'info', 'warn', 'error'")
 )
 
 func main() {
@@ -75,6 +78,20 @@ func main() {
 	logger := log.NewJSONLogger(log.NewSyncWriter(os.Stderr))
 	logger = log.With(logger, "ts", log.DefaultTimestampUTC)
 	logger = log.With(logger, "caller", log.DefaultCaller)
+	switch strings.ToLower(*logLevel) {
+	case "debug":
+		logger = level.NewFilter(logger, level.AllowDebug())
+	case "warn":
+		logger = level.NewFilter(logger, level.AllowWarn())
+	case "error":
+		logger = level.NewFilter(logger, level.AllowError())
+	case "info":
+		logger = level.NewFilter(logger, level.AllowInfo())
+	default:
+		level.Error(logger).Log("msg",
+			"--log.level can only be one of 'debug', 'info', 'warn', 'error'")
+		os.Exit(1)
+	}
 
 	metrics := prometheus.NewRegistry()
 	metrics.MustRegister(
