[Bug 1999711] Re: Snmptrapd cannot reconnect to MySQL server after hitting MySQL wait_timeout

[ChengEn, Du]

@dgadomski @ahasenack
Sorry for not noticing the follow-up commit.
The build error doesn't happen in ubuntu but maybe on other platforms.
For integrity, I uploaded new patches and please use those for testing.
Again, sorry for any inconvenience.

@ahasenack
Here are the steps to reproduce the issue.
https://pastebin.canonical.com/p/MkZ9PR7kmh/
Xenial will not have any problems because it uses an older mysql version.
Another thing is Lunar seems to apply the patch already (able to get the patch by 'pull-lp-source net-snmp lunar').
So I uploaded another patch to cover the build error patch upstream.

Please don't hesitate to let me know if you encounter any problems
during the test.

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https://bugs.launchpad.net/bugs/1999711

Title:
  Snmptrapd cannot reconnect to MySQL server after hitting MySQL
  wait_timeout

Status in net-snmp package in Ubuntu:
  In Progress
Status in net-snmp source package in Bionic:
  In Progress
Status in net-snmp source package in Focal:
  In Progress
Status in net-snmp source package in Jammy:
  In Progress
Status in net-snmp source package in Kinetic:
  In Progress
Status in net-snmp source package in Lunar:
  In Progress

Bug description:
  [Impact]
  wait_timeout is the number of seconds the MySQL server waits for activity before closing the connection.
  MySQL v8.0.24 writes the reason for the connection before closing it, and the client receives a more informative error message (ER_CLIENT_INTERACTION_TIMEOUT).
  Snmptrapd does not handle this error code, so the connection will not reconnect to the MySQL server afterward.

  [Test Plan]
  1. Setup MySQL server and modify wait_timeout to 15 in /etc/MySQL/mysql.conf.d/mysqld.cnf
  2. Setup snmptrapd and execute snmptrap command
  3. Sleep 15 seconds and re-execute snmptrap command, then the connection will fail until the snmptrapd service restarted

  [Where problems could occur]
  Once the error happens, snmptrapd will keep the sql commands and resend it after reconnecting to the MySQL server.
  The regression can be considered as low.

  [Other Info]

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