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

[ChengEn, Du]

Attached is a patch that resolves the issue on Bionic.

** Patch added: "bionic_snmptrapd_mysql_reconnection.debdiff"
   https://bugs.launchpad.net/ubuntu/+source/net-snmp/+bug/1999711/+attachment/5647951/+files/bionic_snmptrapd_mysql_reconnection.debdiff

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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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