Comment 2 for bug 1973177

Reviewed: https://review.opendev.org/c/openstack/charm-mysql-router/+/841708
Committed: https://opendev.org/openstack/charm-mysql-router/commit/5942b035f6ed136632b7a20711a0422ca561e0a6
Submitter: "Zuul (22348)"
Branch: master

commit 5942b035f6ed136632b7a20711a0422ca561e0a6
Author: Liam Young <email address hidden>
Date: Fri May 13 09:25:19 2022 +0000

    Restart router if connections fail with 2003 code

    At the moment if a connection through the router fails after a
    configuration update the router is only restarted if the connection
    error has a code of 2013 but often the error thrown is 2003 (see
    *1) . This patch alters the charms
    behaviour to also restart the router on a 2013 error.

    While testing this patch it became apparent that a connection
    attempt through the router immediatly after the router has been
    restarted very often fail. So, the connection attempt has been
    moved into its own method with its own tenacity retry logic.
    A side effect of this is that the total possible wait time
    has increased from 5 * 10 (outer tenacity loop) to 5 * 10 * 5
    (outer tenacity loop and inner tenacity loop).

    *1 https://dev.mysql.com/doc/mysql-errors/8.0/en/client-error-reference.html

    Closes-Bug: #1973177
    Change-Id: I9c2846bf4f21d2dcb1958bee4c9fa72dd4464b6c