Gerrit: Gitiles auth-links could still be broken.

This change includes a much more robust way to insert the /a/-
prefix in the correct place.

We now check that gitiles-files are actually served from the
Gerrit-server and if so, the authentication prefix is inserted after
Gerrit's baseUrl.

Signed-off-by: Gustaf Lundh <gustaf.lundh@axis.com>

.changeset/grumpy-papayas-tie.md

@@ -0,0 +1,5 @@
+---
+'@backstage/integration': patch
+---
+
+Gerrit: Gitiles auth-links could still be broken

packages/integration/src/gerrit/core.test.ts

@@ -37,15 +37,17 @@ describe('gerrit core', () => {
   describe('buildGerritGitilesArchiveUrl', () => {
     const config: GerritIntegrationConfig = {
       host: 'gerrit.com',
+      baseUrl: 'https://gerrit.com',
       gitilesBaseUrl: 'https://gerrit.com/gitiles',
     };
     const configWithPath: GerritIntegrationConfig = {
       host: 'gerrit.com',
-      gitilesBaseUrl: 'https://gerrit.com/path/gitiles',
+      baseUrl: 'https://gerrit.com/gerrit',
+      gitilesBaseUrl: 'https://gerrit.com/gerrit/plugins/gitiles',
     };
-    const configWithPathSlash: GerritIntegrationConfig = {
+    const configWithDedicatedGitiles: GerritIntegrationConfig = {
       host: 'gerrit.com',
-      gitilesBaseUrl: 'https://gerrit.com/path1/path2/gitiles/',
+      gitilesBaseUrl: 'https://dedicated-gitiles-server.com/gerrit/gitiles',
     };
     it('can create an archive url for a branch', () => {
       expect(buildGerritGitilesArchiveUrl(config, 'repo', 'dev', '')).toEqual(
@@ -84,19 +86,19 @@ describe('gerrit core', () => {
       expect(
         buildGerritGitilesArchiveUrl(authConfig, 'repo', 'dev', 'docs'),
       ).toEqual(
-        'https://gerrit.com/path/a/gitiles/repo/+archive/refs/heads/dev/docs.tar.gz',
+        'https://gerrit.com/gerrit/a/plugins/gitiles/repo/+archive/refs/heads/dev/docs.tar.gz',
       );
     });
     it('can create an authenticated url when auth is enabled and an url-path + slash is used', () => {
       const authConfig = {
-        ...configWithPathSlash,
+        ...configWithDedicatedGitiles,
         username: 'username',
         password: 'password',
       };
       expect(
         buildGerritGitilesArchiveUrl(authConfig, 'repo', 'dev', 'docs'),
       ).toEqual(
-        'https://gerrit.com/path1/path2/a/gitiles/repo/+archive/refs/heads/dev/docs.tar.gz',
+        'https://dedicated-gitiles-server.com/gerrit/gitiles/repo/+archive/refs/heads/dev/docs.tar.gz',
       );
     });
   });

packages/integration/src/gerrit/core.ts

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import { logger } from '@azure/identity';
 import { trimStart } from 'lodash';
 import { GerritIntegrationConfig } from './config';
 
@@ -156,14 +157,18 @@ export function getAuthenticationPrefix(
 export function getGitilesAuthenticationUrl(
   config: GerritIntegrationConfig,
 ): string {
-  const parsedUrl = new URL(config.gitilesBaseUrl!);
-  parsedUrl.pathname = parsedUrl.pathname.replace(/\/?$/, '');
-  parsedUrl.pathname = parsedUrl.pathname.replace(
-    /\/([^\/]*)$/,
-    `${getAuthenticationPrefix(config)}$1`,
-  );
-
-  return parsedUrl.toString();
+  if (config.gitilesBaseUrl!.startsWith(config.baseUrl!)) {
+    return config.gitilesBaseUrl!.replace(
+      config.baseUrl!.concat('/'),
+      config.baseUrl!.concat(getAuthenticationPrefix(config)),
+    );
+  }
+  if (config.password) {
+    logger.warning(
+      'Since the baseUrl (Gerrit) is not part of the gitilesBaseUrl, an authentication URL could not be constructed.',
+    );
+  }
+  return config.gitilesBaseUrl!;
 }
 
 /**