allow multiple docker providers, added file provider support

src/go-proxy/proxy_config.go

@@ -3,20 +3,40 @@ package main
 import "fmt"
 
 type ProxyConfig struct {
-	id          string
 	Alias       string
 	Scheme      string
 	Host        string
 	Port        string
-	LoadBalance string
+	LoadBalance string // docker provider only
 	Path        string // http proxy only
-	PathMode    string // http proxy only
+	PathMode    string `yaml:"path_mode"` // http proxy only
+
+	provider 	*Provider
 }
 
-func NewProxyConfig() ProxyConfig {
-	return ProxyConfig{}
+func NewProxyConfig(provider *Provider) ProxyConfig {
+	return ProxyConfig{
+		provider: provider,
+	}
 }
 
-func (cfg *ProxyConfig) UpdateId() {
-	cfg.id = fmt.Sprintf("%s-%s-%s-%s-%s", cfg.Alias, cfg.Scheme, cfg.Host, cfg.Port, cfg.Path)
+// used by `GetFileProxyConfigs`
+func (cfg *ProxyConfig) SetDefault() error {
+	if cfg.Alias == "" {
+		return fmt.Errorf("alias is required")
+	}
+	if cfg.Scheme == "" {
+		cfg.Scheme = "http"
+	}
+	if cfg.Host == "" {
+		return fmt.Errorf("host is required for %q", cfg.Alias)
+	}
+	if cfg.Port == "" {
+		cfg.Port = "80"
+	}
+	return nil
+}
+
+func (cfg *ProxyConfig) GetID() string {
+	return fmt.Sprintf("%s-%s-%s-%s-%s", cfg.Alias, cfg.Scheme, cfg.Host, cfg.Port, cfg.Path)
 }