update-check: T7945: Improve reliability during early boot and error handling

During early boot not all resources are ready for HTTP request, so
`vyos.version.get_remote_version` may fail once and the update check is then
delayed for 12 hours, leaving the router unaware of updates.

Fix by adding retries/backoff and improved error handling so transient startup
network failures don't suppress update checks for the next interval.

1 files changed, 11 insertions, 1 deletions

diff --git a/python/vyos/version.py b/python/vyos/version.py
index 01986e4da..d62778c4b 100644
--- a/python/vyos/version.py
+++ b/python/vyos/version.py
@@ -34,6 +34,7 @@ import os
 import requests
 import vyos.defaults
 from vyos.system.image import is_live_boot
+from urllib3.util import retry
 
 from vyos.utils.file import read_file
 from vyos.utils.file import read_json
@@ -124,9 +125,18 @@ def get_remote_version(url):
       }
     ]
     """
+
     headers = {}
+    session = requests.Session()
+
+    # By default, `requests` lib. does not retry failed connections
+    # and this code implements automatic retries using the next wait time range:
+    #   - 0.15, 0.30, 0.60, 1.20 and 2.40 seconds.
+    for adapter in session.adapters.values():
+        adapter.max_retries = retry.Retry(total=5, backoff_factor=0.15)
+
     try:
-        remote_data = requests.get(url=url, headers=headers)
+        remote_data = session.get(url=url, headers=headers)
         remote_data.raise_for_status()
         if remote_data.status_code != 200:
             return False