Remove private field in http config

The private field in http config is causing issue while implementing in
Prometheus. It was there to be nice with importers who would import the
code and not call Validate(). I still want to be nice so I have added a
workaround for those users.

Signed-off-by: Julien Pivotto <[email protected]>

config/http_config.go

@@ -111,9 +111,6 @@ type HTTPClientConfig struct {
 	ProxyURL URL `yaml:"proxy_url,omitempty"`
 	// TLSConfig to use to connect to the targets.
 	TLSConfig TLSConfig `yaml:"tls_config,omitempty"`
-	// Used to make sure that the configuration is valid and that BearerToken to
-	// Authorization.Credentials change has been handled.
-	valid bool
 }
 
 // SetDirectory joins any relative file paths with dir.
@@ -169,8 +166,6 @@ func (c *HTTPClientConfig) Validate() error {
 			c.BearerTokenFile = ""
 		}
 	}
-
-	c.valid = true
 	return nil
 }
 
@@ -207,12 +202,6 @@ func NewClientFromConfig(cfg HTTPClientConfig, name string, disableKeepAlives, e
 // NewRoundTripperFromConfig returns a new HTTP RoundTripper configured for the
 // given config.HTTPClientConfig. The name is used as go-conntrack metric label.
 func NewRoundTripperFromConfig(cfg HTTPClientConfig, name string, disableKeepAlives, enableHTTP2 bool) (http.RoundTripper, error) {
-	// Make sure that the configuration is valid.
-	if !cfg.valid {
-		if err := cfg.Validate(); err != nil {
-			return nil, err
-		}
-	}
 	newRT := func(tlsConfig *tls.Config) (http.RoundTripper, error) {
 		// The only timeout we care about is the configured scrape timeout.
 		// It is applied on request. So we leave out any timings here.
@@ -254,6 +243,13 @@ func NewRoundTripperFromConfig(cfg HTTPClientConfig, name string, disableKeepAli
 		} else if cfg.Authorization != nil && len(cfg.Authorization.CredentialsFile) > 0 {
 			rt = NewAuthorizationCredentialsFileRoundTripper(cfg.Authorization.Type, cfg.Authorization.CredentialsFile, rt)
 		}
+		// Backwards compatibility, be nice with importers who would not have
+		// called Validate().
+		if len(cfg.BearerToken) > 0 {
+			rt = NewAuthorizationCredentialsRoundTripper("Bearer", cfg.Authorization.Credentials, rt)
+		} else len(cfg.BearerTokenFile) > 0 {
+			rt = NewAuthorizationCredentialsFileRoundTripper("Bearer", cfg.Authorization.CredentialsFile, rt)
+		}
 
 		if cfg.BasicAuth != nil {
 			rt = NewBasicAuthRoundTripper(cfg.BasicAuth.Username, cfg.BasicAuth.Password, cfg.BasicAuth.PasswordFile, rt)