From 536e435c06ddba628c85369c73d9683cdb8ac802 Mon Sep 17 00:00:00 2001
From: yuvipanda <yuvipanda@gmail.com>
Date: Sun, 19 May 2019 22:29:18 -0700
Subject: [PATCH] Retry downloading traefik if it fails

Fixes #314
---
 setup.py        |  1 +
 tljh/traefik.py | 10 ++++++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/setup.py b/setup.py
index 61f8ead..4597a95 100644
--- a/setup.py
+++ b/setup.py
@@ -15,6 +15,7 @@ setup(
         'jinja2',
         'pluggy>0.7<1.0',
         'passlib',
+        'backoff',
         'jupyterhub-traefik-proxy==0.1.*'
     ],
     entry_points={
diff --git a/tljh/traefik.py b/tljh/traefik.py
index 4581953..4e05b7a 100644
--- a/tljh/traefik.py
+++ b/tljh/traefik.py
@@ -1,10 +1,11 @@
 """Traefik installation and setup"""
 import hashlib
 import os
-from urllib.request import urlretrieve
+from urllib.request import urlretrieve, ContentTooShortError
 
 from jinja2 import Template
 from passlib.apache import HtpasswdFile
+import backoff
 
 from tljh.configurer import load_config
 
@@ -26,7 +27,12 @@ def checksum_file(path):
             hasher.update(chunk)
     return hasher.hexdigest()
 
-
+@backoff.on_exception(
+    backoff.expo,
+    # Retry when connection is reset or we think we didn't download entire file
+    (ConnectionResetError, ContentTooShortError),
+    max_tries=2
+)
 def ensure_traefik_binary(prefix):
     """Download and install the traefik binary"""
     traefik_bin = os.path.join(prefix, "bin", "traefik")