Migrate path of logrotate.d configration

[kenhys]

Before: /etc/logrotate.d/td-agent
  If td-agent user/group exists, renaming td-agent
  to fluent user/group then rewrite logrotate.d configuration.
  But, it may fail if user modify that configuration unexpected
  way.

After: /etc/logrotate.d/fluentd

  If td-agent user/group exists (e.g upgrading from v4), create
  _fluent user/group as same uid/gid. If not, just create new _fluent
  user/group (no td-agent user/group).

  This approach make easy to migrate /etc/logrotate.d/td-agent
  configuration file without modification.

Additionally, rewrite /etc/logrotate.d/td-agent path of pid
because the pid file will be dynamically created/destroyed.

[daipom]

Thanks for this fix!
Indeed, we have to update the file /etc/logrotate.d for the new package.
Do we also need to update the USER and GROUP name to _fluentd for the deb package?

For migration, I have the following concerns.

• Shouldn't the old rotate config /etc/logrotate.d/td-agent work as is after the update?
  • Because we have the alias to access the old path: /var/log/td-agent/td-agent.log
• So, I think we should not make the new rotate config, and continue to use the old one as is.
  • Possibly, we need to migrate USER and GROUP settings, but the other migration process seems to be not needed.

I confirmed the alias /var/log/td-agent work as expected for rotation:

/etc/logrotate.d/td-agent

/var/log/td-agent/td-agent.log {
  #daily
  size 1
  rotate 30
  compress
  delaycompress
  notifempty
  create 640 _fluentd _fluentd
  sharedscripts
  postrotate
    pid=/var/run/fluent/fluentd.pid
    if [ -s "$pid" ]
    then
      kill -USR1 "$(cat $pid)"
    fi
  endscript
}

log files:

/var/log/fluent/td-agent.log

Run rotate: $ sudo logrotate -s state /etc/logrotate.d/td-agent

rotated log files:

/var/log/fluent/td-agent.log
/var/log/fluent/td-agent.log.1

[kenhys]

It may be a simple solution to do:

1st approach PR:

• Ship /etc/logrotate.d/fluentd
• Rewrite to old path in /etc/logroate.d/fluentd
• Remove /etc/logrotate.d/td-agent not to conflict with

2nd approach PR:

• Ship /etc/logrotate.d/flentd (it use new path)
  • thus, both of /etc/logrotate.d/td-agent and /etc/logrotate.d/fluentd is effective.
• Replace user/group in /etc/logrotate.d/td-agent

3rd approach:

• Instead of renaming td-agent user/group, add _fluentd/_fluentd user/group which uid is same as td-agent.

[kenhys]

Try 3rd approach whether it will work as expected.

[kenhys]

3rd approach is not bad, but tend to be broken on some deb platform. 🤔
we need to tackle on another PR.

[daipom]

I confirmed this basically works as expected on Ubuntu Focal.

There was one problem about SIGUSR1 signal on rotation.
I commented on it below.

[kenhys]

Added fix for logrotate.d/td-agent

[daipom]

I will confirm it!

[daipom]

Is it intentional that 43e9343 was added into this PR?

[kenhys]

Is it intentional that 43e9343 was added into this PR?

It should be seperate PR.

[daipom]

I confirmed that the SIGUSR1 worked correctly on rotation!
LGTM.

[kenhys]

Thanks!