add merge MR support to Gitlab

Signed-off-by: davidwin93 <dave.winiarski@zapier.com>

pkg/vcs/gitlab/client.go

@@ -121,6 +121,12 @@ func (c *GitlabClient) GetCommitStatuses(ctx context.Context, projectID, commitS
 
 	return statuses
 }
+func (c *GitlabClient) MergeMR(ctx context.Context, mrIID int, project string) error {
+	_, span := otel.Tracer("TFC").Start(ctx, "MergeMR")
+	defer span.End()
+	_, _, err := c.client.MergeRequests.AcceptMergeRequest(project, mrIID, &gogitlab.AcceptMergeRequestOptions{})
+	return err
+}
 
 // Crawl the comments on this MR for tfbuddy comments, grab any TFC urls out of them, and delete them.
 func (c *GitlabClient) GetOldRunUrls(ctx context.Context, mrIID int, project string, rootNoteID int) (string, error) {

pkg/vcs/gitlab/mr_status_updater.go

@@ -48,6 +48,7 @@ func (p *RunStatusUpdater) updateCommitStatusForRun(ctx context.Context, run *tf
 		}
 		// The applying phase of a run has completed.
 		p.updateStatus(ctx, gogitlab.Success, "apply", rmd)
+		p.mergeMRIfPossible(ctx, rmd)
 
 	case tfe.RunCanceled:
 		// The run has been discarded. This is a final state.
@@ -196,6 +197,12 @@ func (p *RunStatusUpdater) getLatestPipelineID(ctx context.Context, rmd runstrea
 	return nil
 }
 
+func (p *RunStatusUpdater) mergeMRIfPossible(ctx context.Context, rmd runstream.RunMetadata) error {
+	err := p.client.MergeMR(ctx, rmd.GetMRInternalID(), rmd.GetMRProjectNameWithNamespace())
+	log.Debug().AnErr("err", err).Msg("merge MR")
+	return err
+}
+
 // configureBackOff returns a backoff configuration to use to retry requests
 func configureBackOff() *backoff.ExponentialBackOff {
 

pkg/vcs/interfaces.go

@@ -18,6 +18,7 @@ type GitClient interface {
 	SetCommitStatus(ctx context.Context, projectWithNS string, commitSHA string, status CommitStatusOptions) (CommitStatus, error)
 	GetPipelinesForCommit(ctx context.Context, projectWithNS string, commitSHA string) ([]ProjectPipeline, error)
 	GetOldRunUrls(ctx context.Context, mrIID int, project string, rootCommentID int) (string, error)
+	MergeMR(ctx context.Context, mrIID int, project string) error
 }
 type GitRepo interface {
 	FetchUpstreamBranch(string) error