[action] [PR:16490] Fix potentially not having any loopback address on lo interface #16627

mssonicbld · 2023-09-21T06:01:23Z

Why I did it

In #15080, there was a command added to re-add 127.0.0.1/8 to the lo interface when the networking configuration is being brought down. However, the trigger for that command is down, which, looking at ifupdown2 configuration files, runs immediately after 127.0.0.1/16 is removed. This means there may be a period of time where there are no loopback addresses assigned to the lo interface, and redis commands will fail.

Work item tracking

Microsoft ADO (number only): 24833037

How I did it

Fix this by changing this to pre-down, which should run well before 127.0.0.1/16 is removed, and should always leave lo with a loopback address.

How to verify it

This is a race condition with a small timing window for the issue to occur. Killing the teamd container or repeated config reloads may be the best way to try to trigger this.

Which release branch to backport (provide reason below if selected)

Tested branch (Please provide the tested image version)

master branch, with a few config reloads
20220531.38

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

…c-net#16490) In sonic-net#15080, there was a command added to re-add 127.0.0.1/8 to the lo interface when the networking configuration is being brought down. However, the trigger for that command is `down`, which, looking at ifupdown2 configuration files, runs immediately after 127.0.0.1/16 is removed. This means there may be a period of time where there are no loopback addresses assigned to the lo interface, and redis commands will fail. Fix this by changing this to pre-down, which should run well before 127.0.0.1/16 is removed, and should always leave lo with a loopback address. Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>

mssonicbld · 2023-09-21T06:01:31Z

Original PR: #16490

mssonicbld · 2023-09-21T22:33:31Z

/azp run Azure.sonic-buildimage

azure-pipelines · 2023-09-21T22:33:42Z