handle automating branch deletion (#1659)

Author: motatoes

backend/controllers/github.go

@@ -468,6 +468,7 @@ func handlePullRequestEvent(gh utils.GithubClientProvider, payload *github.PullR
 	isDraft := payload.PullRequest.GetDraft()
 	commitSha := payload.PullRequest.Head.GetSHA()
 	branch := payload.PullRequest.Head.GetRef()
+	action := *payload.Action
 
 	link, err := models.DB.GetGithubAppInstallationLink(installationId)
 	if err != nil {
@@ -476,13 +477,36 @@ func handlePullRequestEvent(gh utils.GithubClientProvider, payload *github.PullR
 	}
 	organisationId := link.OrganisationId
 
-	diggerYmlStr, ghService, config, projectsGraph, _, _, err := getDiggerConfigForPR(gh, installationId, repoFullName, repoOwner, repoName, cloneURL, prNumber)
-	if err != nil {
-		ghService, _, err := utils.GetGithubService(gh, installationId, repoFullName, repoOwner, repoName)
+	ghService, _, ghServiceErr := utils.GetGithubService(gh, installationId, repoFullName, repoOwner, repoName)
+	if ghServiceErr != nil {
+		log.Printf("GetGithubService error: %v", err)
+		return fmt.Errorf("error getting ghService to post error comment")
+	}
+
+	// here we check if pr was closed and automatic deletion is enabled, to avoid errors when
+	// pr is merged and the branch does not exist we handle that gracefully
+	if action == "closed" {
+		branchName, _, err := ghService.GetBranchName(prNumber)
 		if err != nil {
-			log.Printf("GetGithubService error: %v", err)
-			return fmt.Errorf("error getting ghService to post error comment")
+			utils.InitCommentReporter(ghService, prNumber, fmt.Sprintf(":x: Could not retrive PR details, error: %v", err))
+			log.Printf("Could not retrive PR details error: %v", err)
+			return fmt.Errorf("Could not retrive PR details: %v", err)
 		}
+		branchExists, err := ghService.CheckBranchExists(branchName)
+		if err != nil {
+			utils.InitCommentReporter(ghService, prNumber, fmt.Sprintf(":x: Could not check if branch exists, error: %v", err))
+			log.Printf("Could not check if branch exists, error: %v", err)
+			return fmt.Errorf("Could not check if branch exists: %v", err)
+
+		}
+		if !branchExists {
+			log.Printf("automating branch deletion is configured, ignoring pr closed event")
+			return nil
+		}
+	}
+
+	diggerYmlStr, ghService, config, projectsGraph, _, _, err := getDiggerConfigForPR(gh, installationId, repoFullName, repoOwner, repoName, cloneURL, prNumber)
+	if err != nil {
 		utils.InitCommentReporter(ghService, prNumber, fmt.Sprintf(":x: Could not load digger config, error: %v", err))
 		log.Printf("getDiggerConfigForPR error: %v", err)
 		return fmt.Errorf("error getting digger config")

libs/ci/github/github.go

@@ -334,6 +334,17 @@ func (svc GithubService) GetBranchName(prNumber int) (string, string, error) {
 	return pr.Head.GetRef(), pr.Head.GetSHA(), nil
 }
 
+func (svc GithubService) CheckBranchExists(branchName string) (bool, error) {
+	_, resp, err := svc.Client.Repositories.GetBranch(context.Background(), svc.Owner, svc.RepoName, branchName, 3)
+	if err != nil {
+		if resp != nil && resp.StatusCode == 404 {
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}
+
 func ConvertGithubPullRequestEventToJobs(payload *github.PullRequestEvent, impactedProjects []digger_config.Project, requestedProject *digger_config.Project, config digger_config.DiggerConfig) ([]scheduler.Job, bool, error) {
 	workflows := config.Workflows
 	jobs := make([]scheduler.Job, 0)