read BUILDKITD_LOG_FORMAT env

Author: michael

cmd/buildctl/main.go

@@ -116,6 +116,9 @@ func main() {
 		debugEnabled = context.GlobalBool("debug")
 		// Use Format flag to control log formatter
 		logFormat := context.GlobalString("log-format")
+		if logFormat == "" {
+        		logFormat = os.Getenv("BUILDKITD_LOG_FORMAT")
+	        }  
 		switch logFormat {
 		case "json":
 			logrus.SetFormatter(&logrus.JSONFormatter{})

cmd/buildkitd/main.go

@@ -183,6 +183,7 @@ func main() {
 			Name:  "log-format",
 			Usage: "log formatter: json or text",
 			Value: "text",
+			EnvVar: "BUILDKITD_LOG_FORMAT",
 		},
 		cli.StringFlag{
 			Name:  "group",