DPE-1799 Add rotation of mysqlrouter logs

[shayancanonical]

Issue

We do not currently have rotation of mysqlrouter logs

Solution

• Add logrotate config to the workload container
• Use pebble on the workload container to run a logrotate dispatcher script (which calls logrotate with the above config)
• Add integration test

TODO

Attempt to run logrotate as non-root user

[carlcsaposs-canonical]

question: will this override the summary for mysql router service since they're using the same layer?

also to confirm, does override:replace within the service only override the logrotate service?

[shayancanonical]

https://github.com/canonical/pebble#layer-specification indicates it only overrides the service with the same name. i ran a small test to confirm this

[carlcsaposs-canonical]

what about the summary?

[shayancanonical]

not sure what you mean to ask. a summary is a field of the service object, and thus gets overwritten when replace: override is specified

[carlcsaposs-canonical]

is it part of the service? it looks like it's part of the layer—and it seems like it will override the summary from the layer with the mysql router service

[shayancanonical]

to be honest, i don't think the layer summary is overwritten/persisted in that way.

the following is the pebble plan:

root@mysql-router-k8s-0:/# pebble plan 
services:
    logrotate_executor:
        summary: Logrotate executor
        startup: enabled
        override: replace
        command: python3 /logrotate_executor.py
        user: mysql
        group: mysql
    mysql_router:
        summary: MySQL Router
        startup: enabled
        override: replace
        command: mysqlrouter --config /etc/mysqlrouter/mysqlrouter.conf
        user: mysql
        group: mysql

there is no way to inspect the pebble layers

[carlcsaposs-canonical]

if it isn't persisted, should we be writing it at all?

[carlcsaposs-canonical]

no way to inspect the pebble layers

I think there might be in the filesystem

[shayancanonical]

it is possible that pebble keeps track of the summary of the layers, but it is not exposed to the user with any of the pebble commands. Either way, I removed the layer summary in 86e8516

[carlcsaposs-canonical]

looks great!

[carlcsaposs-canonical]

nits