Merge pull request #1145 from github/criemen/fix-ff-crash

Don't crash if we are unable to get a response from the feature-flag endpoint.

Author: criemen

lib/feature-flags.js

@@ -67,6 +67,37 @@ for (const variant of ALL_FEATURE_FLAGS_DISABLED_VARIANTS) {
   });
 }
 
+test("API response missing", async (t) => {
+  await withTmpDir(async (tmpDir) => {
+    setupActionsVars(tmpDir, tmpDir);
+
+    const loggedMessages = [];
+    const featureFlags = new GitHubFeatureFlags(
+      { type: GitHubVariant.DOTCOM },
+      testApiDetails,
+      testRepositoryNwo,
+      getRecordingLogger(loggedMessages)
+    );
+
+    mockFeatureFlagApiEndpoint(403, {});
+
+    for (const flag of Object.values(FeatureFlag)) {
+      t.assert((await featureFlags.getValue(flag)) === false);
+    }
+
+    for (const featureFlag of ["ml_powered_queries_enabled"]) {
+      t.assert(
+        loggedMessages.find(
+          (v: LoggedMessage) =>
+            v.type === "debug" &&
+            v.message ===
+              `No feature flags API response for ${featureFlag}, considering it disabled.`
+        ) !== undefined
+      );
+    }
+  });
+});
+
 test("Feature flags are disabled if they're not returned in API response", async (t) => {
   await withTmpDir(async (tmpDir) => {
     setupActionsVars(tmpDir, tmpDir);

lib/feature-flags.js.map

@@ -31,14 +31,21 @@ export class GitHubFeatureFlags implements FeatureFlags {
   ) {}
 
   async getValue(flag: FeatureFlag): Promise<boolean> {
-    const response = (await this.getApiResponse())[flag];
+    const response = await this.getApiResponse();
     if (response === undefined) {
+      this.logger.debug(
+        `No feature flags API response for ${flag}, considering it disabled.`
+      );
+      return false;
+    }
+    const flagValue = response[flag];
+    if (flagValue === undefined) {
       this.logger.debug(
         `Feature flag '${flag}' undefined in API response, considering it disabled.`
       );
       return false;
     }
-    return response;
+    return flagValue;
   }
 
   private async getApiResponse(): Promise<FeatureFlagsApiResponse> {