fixed startup crash for file provider

src/common/constants.go

@@ -37,12 +37,6 @@ const (
 
 const DockerHostFromEnv = "$DOCKER_HOST"
 
-const (
-	ProxyHTTPPort  = ":80"
-	ProxyHTTPSPort = ":443"
-	APIHTTPPort    = ":8888"
-)
-
 var WellKnownHTTPPorts = map[uint16]bool{
 	80:   true,
 	8000: true,

src/common/env.go

@@ -6,9 +6,22 @@ import (
 	U "github.com/yusing/go-proxy/utils"
 )
 
-var NoSchemaValidation = getEnvBool("GOPROXY_NO_SCHEMA_VALIDATION")
-var IsDebug = getEnvBool("GOPROXY_DEBUG")
+var (
+	NoSchemaValidation = getEnvBool("GOPROXY_NO_SCHEMA_VALIDATION")
+	IsDebug            = getEnvBool("GOPROXY_DEBUG")
+	ProxyHTTPPort      = ":" + getEnv("GOPROXY_HTTP_PORT", "80")
+	ProxyHTTPSPort     = ":" + getEnv("GOPROXY_HTTPS_PORT", "443")
+	APIHTTPPort        = ":" + getEnv("GOPROXY_API_PORT", "8888")
+)
 
 func getEnvBool(key string) bool {
 	return U.ParseBool(os.Getenv(key))
 }
+
+func getEnv(key string, defaultValue string) string {
+	value, ok := os.LookupEnv(key)
+	if !ok {
+		value = defaultValue
+	}
+	return value
+}