Refine makefile.

proxy/.gitignore

@@ -1,3 +1,4 @@
 .idea
 srs-proxy
-.env
+.env
+.go-formarted

proxy/Makefile

@@ -2,17 +2,22 @@
 
 all: build
 
-build: fmt
+build: fmt ./srs-proxy
+
+./srs-proxy: *.go
 	go build -o srs-proxy .
 
 test:
 	go test ./...
 
-fmt:
+fmt: ./.go-formarted
+
+./.go-formarted: *.go
+	touch .go-formarted
 	go fmt ./...
 
 clean:
-	rm -f srs-proxy
+	rm -f srs-proxy .go-formarted
 
 run: fmt
 	go run .

proxy/env.go

@@ -30,6 +30,7 @@ func loadEnvFile(ctx context.Context) error {
 	return nil
 }
 
+// buildDefaultEnvironmentVariables setups the default environment variables.
 func buildDefaultEnvironmentVariables(ctx context.Context) {
 	// Whether enable the Go pprof.
 	setEnvDefault("GO_PPROF", "")