From 59fe2714741133989a7beed613f1eeb67c18c54e Mon Sep 17 00:00:00 2001
From: Mitar <mitar.git@tnode.com>
Date: Thu, 12 Dec 2019 20:02:24 -0800
Subject: [PATCH] feat: retry transient HTTP errors

Fixes #970
---
 docs/api-usage.rst | 18 ++++++++++++++++++
 gitlab/__init__.py |  6 +++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/docs/api-usage.rst b/docs/api-usage.rst
index 19b959317..fc2314ee8 100644
--- a/docs/api-usage.rst
+++ b/docs/api-usage.rst
@@ -348,3 +348,21 @@ throttled, you can set this parameter to -1. This parameter is ignored if
 .. warning::
 
    You will get an Exception, if you then go over the rate limit of your GitLab instance.
+
+Transient errors
+----------------
+
+GitLab server can sometimes return a transient HTTP error.
+python-gitlab can automatically retry in such case, when
+``retry_transient_errors`` argument is set to ``True``.  When enabled,
+HTTP error codes 500 (Internal Server Error), 502 (502 Bad Gateway),
+503 (Service Unavailable), and 504 (Gateway Timeout) are retried.  By
+default an exception is raised for these errors.
+
+.. code-block:: python
+
+   import gitlab
+   import requests
+
+   gl = gitlab.gitlab(url, token, api_version=4)
+   gl.projects.list(all=True, retry_transient_errors=True)
diff --git a/gitlab/__init__.py b/gitlab/__init__.py
index 3605b80b3..09b7b81bb 100644
--- a/gitlab/__init__.py
+++ b/gitlab/__init__.py
@@ -518,6 +518,8 @@ def http_request(
 
         # obey the rate limit by default
         obey_rate_limit = kwargs.get("obey_rate_limit", True)
+        # do not retry transient errors by default
+        retry_transient_errors = kwargs.get("retry_transient_errors", False)
 
         # set max_retries to 10 by default, disable by setting it to -1
         max_retries = kwargs.get("max_retries", 10)
@@ -531,7 +533,9 @@ def http_request(
             if 200 <= result.status_code < 300:
                 return result
 
-            if 429 == result.status_code and obey_rate_limit:
+            if (429 == result.status_code and obey_rate_limit) or (
+                result.status_code in [500, 502, 503, 504] and retry_transient_errors
+            ):
                 if max_retries == -1 or cur_retries < max_retries:
                     wait_time = 2 ** cur_retries * 0.1
                     if "Retry-After" in result.headers: