feat(gitlab): allow override server version (#11416)

docs/usage/self-hosted-experimental.md

@@ -39,3 +39,10 @@ If set to any string, Renovate will use this as the `user-agent` it sends with H
 
 If set to any value, Renovate will use a "hard" `process.exit()` once all work is done, even if a sub-process is otherwise delaying Node.js from exiting.
 See <https://github.com/renovatebot/renovate/issues/8660> for background on why this was created.
+
+## RENOVATE_X_PLATFORM_VERSION
+
+If set, Renovate will use this string as GitLab server version instead of checking via the GitLab API.
+This can be useful when you use the GitLab `CI_JOB_TOKEN` to authenticate Renovate.
+
+Read [platform details](modules/platform/gitlab/index.md) to learn why we need the server version on GitLab.

lib/platform/gitlab/index.md

@@ -3,3 +3,13 @@
 ## Features awaiting implementation
 
 - The `automergeStrategy` configuration option has not been implemented for this platform, and all values behave as if the value `auto` was used. Renovate will accept the Merge Request without further configuration, and respect the strategy defined in the Merge Request, and this cannot be overridden yet
+
+## Server version dependent features
+
+We use the GitLab [version API](https://docs.gitlab.com/ee/api/version.html) to fetch the server version.
+You can use the experimental feature flag [`RENOVATE_X_PLATFORM_VERSION`](https://docs.renovatebot.com/self-hosted-experimental/#renovate_x_platform_version) to set a specific server version.
+By setting the server version yourself, you save a API call that fetches the server version.
+
+- Use `Draft:` MR prefix instead of `WIP:` prefix since `v13.2.0`
+- Do not truncate Markdown body to 25K chars since `v13.4.0`
+- Allow configure reviewers since `v13.9.0`

lib/platform/gitlab/index.ts

@@ -104,11 +104,18 @@ export async function initPlatform({
       ).body;
       platformConfig.gitAuthor = `${user.name} <${user.email}>`;
     }
-    // version is 'x.y.z-edition', so not strictly semver; need to strip edition
-    gitlabVersion = (
-      await gitlabApi.getJson<{ version: string }>('version', { token })
-    ).body.version.split('-')[0];
+    // istanbul ignore if: experimental feature
+    if (process.env.RENOVATE_X_PLATFORM_VERSION) {
+      gitlabVersion = process.env.RENOVATE_X_PLATFORM_VERSION;
+    } else {
+      const version = (
+        await gitlabApi.getJson<{ version: string }>('version', { token })
+      ).body;
+      gitlabVersion = version.version;
+    }
     logger.debug('GitLab version is: ' + gitlabVersion);
+    // version is 'x.y.z-edition', so not strictly semver; need to strip edition
+    [gitlabVersion] = gitlabVersion.split('-');
     defaults.version = gitlabVersion;
   } catch (err) {
     logger.debug(
@@ -117,7 +124,7 @@ export async function initPlatform({
     );
     throw new Error('Init: Authentication failure');
   }
-  draftPrefix = lt(gitlabVersion, '13.2.0')
+  draftPrefix = lt(defaults.version, '13.2.0')
     ? DRAFT_PREFIX_DEPRECATED
     : DRAFT_PREFIX;