Make OAuth 2.0 client_id and client_secret mandatory

config/http_config.go

@@ -210,6 +210,9 @@ func (c *HTTPClientConfig) Validate() error {
 		if c.BasicAuth != nil {
 			return fmt.Errorf("at most one of basic_auth, oauth2 & authorization must be configured")
 		}
+		if len(c.OAuth2.ClientID) < 1 || (len(c.OAuth2.ClientSecret) < 1 || len(c.OAuth2.ClientSecretFile) < 1) {
+			return fmt.Errorf("the oauth2 client_id and either the client_secret or client_secret_file must be configured")
+		}
 		if len(c.OAuth2.ClientSecret) > 0 && len(c.OAuth2.ClientSecretFile) > 0 {
 			return fmt.Errorf("at most one of oauth2 client_secret & client_secret_file must be configured")
 		}

config/http_config_test.go

@@ -107,6 +107,14 @@ var invalidHTTPClientConfigs = []struct {
 		httpClientConfigFile: "testdata/http.conf.oauth2-secret-and-file-set.bad.yml",
 		errMsg:               "at most one of oauth2 client_secret & client_secret_file must be configured",
 	},
+	{
+		httpClientConfigFile: "testdata/http.conf.oauth2-no-client-id.bad.yaml",
+		errMsg:               "the oauth2 client_id and either the client_secret or client_secret_file must be configured",
+	},
+	{
+		httpClientConfigFile: "testdata/http.conf.oauth2-no-client-secret.bad.yaml",
+		errMsg:               "the oauth2 client_id and either the client_secret or client_secret_file must be configured",
+	},
 }
 
 func newTestServer(handler func(w http.ResponseWriter, r *http.Request)) (*httptest.Server, error) {

config/testdata/http.conf.oauth2-no-client-id.bad.yaml

@@ -0,0 +1,2 @@
+oauth2:
+  client_secret: "mysecret"

config/testdata/http.conf.oauth2-no-client-secret.bad.yaml

@@ -0,0 +1,2 @@
+oauth2:
+  client_id: "myclientid"

config/testdata/http.conf.oauth2-secret-and-file-set.bad.yml

@@ -1,3 +1,4 @@
 oauth2:
+  client_id: "myclient"
   client_secret: "mysecret"
   client_secret_file: "mysecret"