feat(ng-dev): create a new label target: automation to be used by bots (#3054)

Create a new label for bots to use for targetting only the branch selected in Github. Additionally,
set up support for the merge and github actions tooling to support this new label' is not a valid
branch name.

PR Close #3054

Author: josephperrott

.github/local-actions/branch-manager/main.js

@@ -130,6 +130,9 @@ export const PR_SCHEMA = {
       ],
     },
   ),
+  author: {
+    login: graphqlTypes.string,
+  },
 };
 
 export type PullRequestFromGithub = typeof PR_SCHEMA;

.github/local-actions/labels-sync/main.js

@@ -13,6 +13,11 @@ export class TargetLabel extends Label {
  * https://docs.google.com/document/d/197kVillDwx-RZtSVOBtPb4BBIAw0E9RT3q3v6DZkykU#heading=h.lkuypj38h15d
  */
 export const targetLabels = createTypedObject(TargetLabel)({
+  TARGET_AUTOMATION: {
+    description:
+      'This PR is targeted to only merge into the branch defined in Github [bot use only]',
+    name: 'target: automation',
+  },
   TARGET_FEATURE: {
     description: 'This PR is targeted for a feature branch (outside of main and semver branches)',
     name: 'target: feature',

github-actions/branch-manager/main.js

@@ -153,6 +153,17 @@ export async function getTargetLabelConfigsForActiveReleaseTrains(
         return [githubTargetBranch];
       },
     },
+    {
+      label: targetLabels['TARGET_AUTOMATION'],
+      branches: (githubTargetBranch) => {
+        if (!isVersionBranch(githubTargetBranch)) {
+          throw new InvalidTargetBranchError(
+            '"target: automation" pull requests can only target a release branch',
+          );
+        }
+        return [githubTargetBranch];
+      },
+    },
   ];
 
   // LTS branches can only be determined if the release configuration is defined, and must be added

github-actions/pull-request-labeling/main.js

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {PullRequestFromGithub} from '../fetch-pull-request.js';
 import {Commit} from '../../../commit-message/parse.js';
 import {ActiveReleaseTrains} from '../../../release/versioning/active-release-trains.js';
 import {Log, red} from '../../../utils/logging.js';
@@ -14,6 +15,9 @@ import {mergeLabels} from '../labels/index.js';
 import {TargetLabel, targetLabels} from '../labels/target.js';
 import {createPullRequestValidation, PullRequestValidation} from './validation-config.js';
 
+/** List of automation robot accounts. */
+const automationBots = ['angular-robot'];
+
 /** Assert the commits provided are allowed to merge to the provided target label. */
 // TODO: update typings to make sure portability is properly handled for windows build.
 export const changesAllowForTargetLabelValidation = createPullRequestValidation(
@@ -28,6 +32,7 @@ class Validation extends PullRequestValidation {
     config: PullRequestConfig,
     releaseTrains: ActiveReleaseTrains,
     labelsOnPullRequest: string[],
+    pullRequest: PullRequestFromGithub,
   ) {
     if (labelsOnPullRequest.includes(mergeLabels['MERGE_FIX_COMMIT_MESSAGE'].name)) {
       Log.debug(
@@ -68,6 +73,10 @@ class Validation extends PullRequestValidation {
         if (hasDeprecations && !releaseTrains.isFeatureFreeze()) {
           throw this._createHasDeprecationsError(targetLabel);
         }
+      case targetLabels['TARGET_AUTOMATION']:
+        if (!automationBots.includes(pullRequest.author.login)) {
+          throw this._createUserUsingAutomationLabelError(targetLabel, pullRequest.author.login);
+        }
         break;
       default:
         Log.warn(red('WARNING: Unable to confirm all commits in the pull request are'));
@@ -98,4 +107,11 @@ class Validation extends PullRequestValidation {
       'or "target: major" label.';
     return this._createError(message);
   }
+
+  private _createUserUsingAutomationLabelError(label: TargetLabel, author: string) {
+    const message =
+      `Cannot merge into branch for "${label.name}" as the pull request is authored by "${author}" ` +
+      `but only known automation bot accounts (${automationBots.join(', ')}) can use this label.`;
+    return this._createError(message);
+  }
 }

github-actions/unified-status-check/main.js

@@ -75,6 +75,7 @@ export async function assertValidPullRequest(
         ngDevConfig.pullRequest,
         activeReleaseTrains,
         labels,
+        pullRequest,
       ),
     );
   }