feat: manifest options to enable auto-merge on release pull requests

src/github.ts

@@ -28,6 +28,7 @@ import {
   FileNotFoundError,
   ConfigurationError,
   isOctokitRequestError,
+  isOctokitGraphqlResponseError,
 } from './errors';
 
 const MAX_ISSUE_BODY_SIZE = 65536;
@@ -213,10 +214,15 @@ interface FileDiff {
 }
 export type ChangeSet = Map<string, FileDiff>;
 
+export type MergeMethod = 'MERGE' | 'SQUASH' | 'REBASE';
+
 interface CreatePullRequestOptions {
   fork?: boolean;
   draft?: boolean;
   reviewers?: [string];
+  autoMerge?: {
+    mergeMethod: MergeMethod;
+  };
   /**
    * If the number of an existing pull request is passed, its HEAD branch and attributes (title, labels, etc) will be
    * updated instead of creating a new pull request.
@@ -1285,6 +1291,18 @@ export class GitHub {
         pullRequest.labels
       );
 
+      // attempt to enable auto-merge
+      if (options?.autoMerge) {
+        try {
+          await this.enablePullRequestAutoMerge(
+            pullRequestNumber,
+            options.autoMerge.mergeMethod
+          );
+        } catch (e: unknown) {
+          this.logger.warn(e as {}, `Failed to enable auto merge. Continuing.`);
+        }
+      }
+
       // assign reviewers
       if (options?.reviewers) {
         try {
@@ -1294,11 +1312,10 @@ export class GitHub {
             pull_number: pullRequestNumber,
             reviewers: options.reviewers,
           });
-        } catch (error) {
-          console.log(
-            `Failed to add reviewers. Continuing anyway: ${
-              isOctokitRequestError(error) ? error.message : error
-            }`
+        } catch (error: unknown) {
+          this.logger.warn(
+            isOctokitRequestError(error) ? error.message : (error as {}),
+            'Failed to add reviewers. Continuing.'
           );
         }
       }
@@ -1353,6 +1370,9 @@ export class GitHub {
         signoffUser?: string;
         fork?: boolean;
         pullRequestOverflowHandler?: PullRequestOverflowHandler;
+        autoMerge?: {
+          mergeMethod: MergeMethod;
+        };
       }
     ): Promise<PullRequest> => {
       //  Update the files for the release if not already supplied
@@ -1388,6 +1408,7 @@ export class GitHub {
         {
           fork: options?.fork,
           existingPrNumber: number,
+          autoMerge: options?.autoMerge,
         }
       );
 
@@ -2273,6 +2294,77 @@ export class GitHub {
   invalidateFileCache() {
     this.fileCache = new RepositoryFileCache(this.octokit, this.repository);
   }
+
+  private async queryPullRequestId(
+    pullRequestNumber: number
+  ): Promise<string | undefined> {
+    const query = `query pullRequestId($owner: String!, $repo: String!, $pullRequestNumber: Int!) {
+        repository(name: $repo, owner: $owner) {
+          pullRequest(number: $pullRequestNumber) {
+            id
+          }
+        }
+      }`;
+    const response = await this.graphqlRequest({
+      query,
+      owner: this.repository.owner,
+      repo: this.repository.repo,
+      pullRequestNumber,
+    });
+
+    this.logger.debug(response, 'queryPullrequestId');
+
+    const id = response?.repository?.pullRequest?.id;
+    if (id) {
+      return id as string;
+    }
+    return undefined;
+  }
+
+  private async mutatePullRequestEnableAutoMerge(
+    pullRequestId: string,
+    mergeMethod: MergeMethod
+  ) {
+    const mutation = `mutation mutateEnableAutoMerge($pullRequestId: ID!, $mergeMethod: PullRequestMergeMethod) {
+      enablePullRequestAutoMerge(
+        input: {pullRequestId: $pullRequestId, mergeMethod: $mergeMethod}
+      ) {
+        pullRequest {
+          autoMergeRequest{
+            authorEmail,
+            commitBody,
+            commitHeadline,
+            enabledAt,
+            enabledBy {
+              login
+            },
+            mergeMethod,
+            pullRequest{
+              id
+            }
+          }
+        }
+      }
+    }`;
+    const response = await this.graphqlRequest({
+      query: mutation,
+      pullRequestId,
+      mergeMethod,
+    });
+
+    this.logger.debug({response}, 'mutatePullrequestEnableAutoMerge');
+  }
+
+  private async enablePullRequestAutoMerge(
+    pullRequestNumber: number,
+    mergeMethod: MergeMethod
+  ) {
+    const prId = await this.queryPullRequestId(pullRequestNumber);
+    if (!prId) {
+      throw new Error(`No id found for pull request ${pullRequestNumber}`);
+    }
+    await this.mutatePullRequestEnableAutoMerge(prId, mergeMethod);
+  }
 }
 
 /**

src/manifest.ts

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 import {ChangelogSection} from './changelog-notes';
-import {GitHub, GitHubRelease, GitHubTag} from './github';
+import {GitHub, GitHubRelease, GitHubTag, MergeMethod} from './github';
 import {Version, VersionsMap} from './version';
 import {Commit, parseConventionalCommits} from './commit';
 import {PullRequest} from './pull-request';
@@ -185,6 +185,7 @@ export interface ManifestOptions {
   separatePullRequests?: boolean;
   plugins?: PluginType[];
   fork?: boolean;
+  autoMerge?: {mergeMethod: MergeMethod};
   signoff?: string;
   manifestPath?: string;
   labels?: string[];
@@ -289,6 +290,7 @@ export class Manifest {
   readonly changesBranch: string;
   private separatePullRequests: boolean;
   readonly fork: boolean;
+  private autoMerge?: {mergeMethod: MergeMethod};
   private signoffUser?: string;
   private labels: string[];
   private skipLabeling?: boolean;
@@ -357,6 +359,7 @@ export class Manifest {
       manifestOptions?.separatePullRequests ??
       Object.keys(repositoryConfig).length === 1;
     this.fork = manifestOptions?.fork || false;
+    this.autoMerge = manifestOptions?.autoMerge;
     this.signoffUser = manifestOptions?.signoff;
     this.releaseLabels =
       manifestOptions?.releaseLabels || DEFAULT_RELEASE_LABELS;
@@ -1034,6 +1037,7 @@ export class Manifest {
       {
         fork: this.fork,
         draft: pullRequest.draft,
+        autoMerge: this.autoMerge,
       }
     );
 
@@ -1065,6 +1069,7 @@ export class Manifest {
         fork: this.fork,
         signoffUser: this.signoffUser,
         pullRequestOverflowHandler: this.pullRequestOverflowHandler,
+        autoMerge: this.autoMerge,
       }
     );
 
@@ -1092,6 +1097,7 @@ export class Manifest {
         fork: this.fork,
         signoffUser: this.signoffUser,
         pullRequestOverflowHandler: this.pullRequestOverflowHandler,
+        autoMerge: this.autoMerge,
       }
     );
     // TODO: consider leaving the snooze label