Merge pull request #154 from ochrstn/fix/gitlab-branch-cannot-merge

fix(gitlab): retry failed merges due to server still processing merge request

Author: christiansiegel

gitopscli/git_api/gitlab_git_repo_api_adapter.py

@@ -1,11 +1,15 @@
 from typing import Optional
+import logging
+import time
 import requests
 
 import gitlab
 from gitopscli.gitops_exception import GitOpsException
 
 from .git_repo_api import GitRepoApi
 
+MAX_MERGE_RETRIES = 5
+
 
 class GitlabGitRepoApiAdapter(GitRepoApi):
     def __init__(
@@ -57,7 +61,22 @@ def create_pull_request(
 
     def merge_pull_request(self, pr_id: int) -> None:
         merge_request = self.__project.mergerequests.get(pr_id)
-        merge_request.merge()
+
+        max_retries = MAX_MERGE_RETRIES
+        while max_retries > 0:
+            try:
+                merge_request.merge()
+                return
+            except gitlab.exceptions.GitlabMRClosedError as ex:
+                # "Branch cannot be merged" error can occur if the server
+                # is still processing the merge request internally
+                max_retries -= 1
+                logging.warning(
+                    "Retry merging pull request. Attempts: (%s/%s)", MAX_MERGE_RETRIES - max_retries, MAX_MERGE_RETRIES
+                )
+                if max_retries == 0:
+                    raise GitOpsException("Error merging pull request: 'Branch cannot be merged'") from ex
+                time.sleep(2.5)
 
     def add_pull_request_comment(self, pr_id: int, text: str, parent_id: Optional[int] = None) -> None:
         merge_request = self.__project.mergerequests.get(pr_id)