config: accept PORT env + ensure colon (#1181)

* config: accept PORT env + ensure colon

* ensure precedence

pkg/config/config.go

@@ -160,12 +160,27 @@ func envOverride(config *Config) error {
 	if err != nil {
 		return err
 	}
+	portEnv := os.Getenv("PORT")
+	// ATHENS_PORT takes precedence over PORT
+	if portEnv != "" && os.Getenv("ATHENS_PORT") == "" {
+		config.Port = portEnv
+	}
 	if config.Port == "" {
 		config.Port = defaultPort
 	}
 	return nil
 }
 
+func ensurePortFormat(s string) string {
+	if len(s) == 0 {
+		return ""
+	}
+	if s[0] != ':' {
+		return ":" + s
+	}
+	return s
+}
+
 func validateConfig(config Config) error {
 	validate := validator.New()
 	err := validate.StructExcept(config, "Storage")