fix(Github): use x-ratelimit-remaining and 429 status code for rate limit detection

Signed-off-by: secustor <sebastian@poxhofer.at>

packages/integration/src/github/GithubIntegration.test.ts

@@ -78,6 +78,31 @@ describe('GithubIntegration', () => {
       ),
     ).toBe('https://github.com/backstage/backstage/edit/master/README.md');
   });
+
+  describe('isRateLimited', () => {
+    const integration = new GithubIntegration({ host: 'h.com' });
+
+    it.each`
+      status | ratelimitRemaining | expected
+      ${404} | ${100}             | ${false}
+      ${429} | ${undefined}       | ${true}
+      ${429} | ${100}             | ${true}
+      ${403} | ${100}             | ${false}
+      ${403} | ${0}               | ${true}
+    `(
+      '(statusCode: $status, header: $ratelimitRemaining) === $expected',
+      ({ status, ratelimitRemaining, expected }) => {
+        const headers = new Headers({
+          'x-ratelimit-remaining': ratelimitRemaining,
+        });
+        const result = integration.isRateLimited({
+          status,
+          headers,
+        } as Response);
+        expect(expected).toBe(result);
+      },
+    );
+  });
 });
 
 describe('replaceGithubUrlType', () => {

packages/integration/src/github/GithubIntegration.ts

@@ -65,6 +65,14 @@ export class GithubIntegration implements ScmIntegration {
   resolveEditUrl(url: string): string {
     return replaceGithubUrlType(url, 'edit');
   }
+
+  isRateLimited(response: Response): boolean {
+    return (
+      response.status === 429 ||
+      (response.status === 403 &&
+        response.headers.get('x-ratelimit-remaining') === '0')
+    );
+  }
 }
 
 /**