Option to disable systemd syslog in docker::run + Document extra_systemd_parameters

[elofu17]

Use Case

A normal docker setup do not syslog container output to the systemd journal (by default container output is placed in json logfiles under /var/lib/docker/containers/*/*.log). Only internal messages from the docker daemon itself are syslogged, not the container output.

However, the puppetlabs docker module builds a systemd service file for each continer to run, and by default, systemd syslogs all stdout and stderr for all services. So suddently a system get double logs. First the direct json-logs in /var/lib/docker/containers/*/*.log and then the same thing is spammed to the journal, and therefore also spammed to /var/log/* (if the system is running a syslog service).

Describe the Solution You Would Like

I want an option to stop the docker::run systemd service syslogging, and only log whatever I have configured in docker, globally or in container specific options.

In docker::run you already have the options syslog_identifier and syslog_facility to tweak the syslog from the systemd service. I would like this new extra option: syslog_enable = true/false (default should be true, because this module has always worked this (incorrect) way)

When set to false, the /etc/systemd/system/docker-containername.service unit should get these two extra lines:

[Service]
StandardOutput=null
StandardError=null

This will mute all output from the container-service, and we're back to a "normal" setup.

Describe Alternatives You've Considered

I see there is an option extra_systemd_parameters, but it is totally undocumented. Can/should it be used to solve the above?

In the meantime I've created this workaround: In the profile where I docker::run my container, I've added this systemd dropin-file:

  file { '/etc/systemd/system/docker-foobar.service.d':
    ensure  => directory,
  }
  file { '/etc/systemd/system/docker-foobar.service.d/mute_output.conf':
    content => "### Managed by puppet ###\n[Service]\nStandardOutput=null\nStandardError=null\n",
    require => File['/etc/systemd/system/docker-foobar.service.d'],
  }

Oh, in any case, please document the extra_systemd_parameters option and give an example how to use it.

[chelnak]

Hey @elofu17, thanks for raising this issue.

Would this be something you'd consider opening a PR for?

[elofu17]

Hi. Unfortunately I'm no developer, so I don't know where or what to modify, otherwise I would have done it instead of describing it in text.

[github-actions[bot]]

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[elofu17]

This ticket should be re-opened by someone with privileges, in my opinion. It was just auto-closed for no particular reason.

[shamil]

As a workaround, I'm using resource collector to accomplish this globally, like:

# this will ensure that docker containers doesn't log to "syslog" or "journald",
# use a resource collector to amend this globally
Docker::Run <||> {
    extra_systemd_parameters => {
        'Service' => {
            'StandardError'  => 'null',
            'StandardOutput' => 'null',
        }
    }
}