Adding 'ExtraHeaders' field on HTTPClientConfig

config/http_config.go

@@ -177,6 +177,8 @@ type HTTPClientConfig struct {
 	// The omitempty flag is not set, because it would be hidden from the
 	// marshalled configuration when set to false.
 	FollowRedirects bool `yaml:"follow_redirects" json:"follow_redirects"`
+	// Extra Headers to be added on the Http Request
+	ExtraHeaders map[string]string `yaml:"extra_headers,omitempty" json:"extra_headers,omitempty"`
 }
 
 // SetDirectory joins any relative file paths with dir.
@@ -418,6 +420,10 @@ func NewRoundTripperFromConfig(cfg HTTPClientConfig, name string, optFuncs ...HT
 			rt = NewBasicAuthRoundTripper(cfg.BasicAuth.Username, cfg.BasicAuth.Password, cfg.BasicAuth.PasswordFile, rt)
 		}
 
+		if cfg.ExtraHeaders != nil && len(cfg.ExtraHeaders) > 0 {
+			rt = NewExtraHeadersRoundTripper(cfg.ExtraHeaders, rt)
+		}
+
 		if cfg.OAuth2 != nil {
 			rt = NewOAuth2RoundTripper(cfg.OAuth2, rt)
 		}
@@ -438,6 +444,26 @@ func NewRoundTripperFromConfig(cfg HTTPClientConfig, name string, optFuncs ...HT
 	return NewTLSRoundTripper(tlsConfig, cfg.TLSConfig.CAFile, newRT)
 }
 
+type extraHeadersRoundTripper struct {
+	extraHeaders map[string]string
+	rt           http.RoundTripper
+}
+
+func (rt *extraHeadersRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	req = cloneRequest(req)
+	if len(rt.extraHeaders) > 0 {
+		for key, value := range rt.extraHeaders {
+			req.Header.Set(key, value)
+		}
+	}
+	return rt.rt.RoundTrip(req)
+}
+
+// NewExtraHeadersRoundTripper adds the provided headers to a request
+func NewExtraHeadersRoundTripper(extraHeaders map[string]string, rt http.RoundTripper) http.RoundTripper {
+	return &extraHeadersRoundTripper{extraHeaders, rt}
+}
+
 type authorizationCredentialsRoundTripper struct {
 	authType        string
 	authCredentials Secret

config/http_config_test.go

@@ -68,6 +68,8 @@ const (
 	ExpectedPassword                  = "42"
 )
 
+var expectedExtraHeaders = map[string]string{"Header1": "Value1", "Header2": "Value2"}
+
 var invalidHTTPClientConfigs = []struct {
 	httpClientConfigFile string
 	errMsg               string
@@ -197,6 +199,26 @@ func TestNewClientFromConfig(t *testing.T) {
 					fmt.Fprint(w, ExpectedMessage)
 				}
 			},
+		},
+		{
+			clientConfig: HTTPClientConfig{
+				ExtraHeaders: expectedExtraHeaders,
+				TLSConfig: TLSConfig{
+					CAFile:             TLSCAChainPath,
+					CertFile:           ClientCertificatePath,
+					KeyFile:            ClientKeyNoPassPath,
+					ServerName:         "",
+					InsecureSkipVerify: false},
+			},
+			handler: func(w http.ResponseWriter, r *http.Request) {
+				for key, value := range expectedExtraHeaders {
+					if r.Header.Get(key) != value {
+						fmt.Fprintf(w, "The received Headers (%s) does not contain all expected headers (%s).", r.Header, expectedExtraHeaders)
+						return
+					}
+				}
+				fmt.Fprint(w, ExpectedMessage)
+			},
 		}, {
 			clientConfig: HTTPClientConfig{
 				BearerTokenFile: BearerTokenFile,