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Andy Arismendi
Asked: 2013-07-19 13:07:35 +0800 CST

Puppet ignore part of templated file

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Is there a way to ignore part of a templated file?

I have a service which has a config file and each time the service starts it writes the start time in the config file. This makes puppet detect a change and since I have it notifying the service it will restart the service. I don't want puppet to restart the service shortly after I have just started it.

So is there a way for to make puppet ignore part of a templated file?

puppet

2 Answers

  1. I don't think this is possible, puppet calculates an md5 of the file to check for file changes. Is it possible to write the start time to another file?

    • 0

  2. My solution is similiar to Zoredache's, but varies slightly in that you don't need an intelligent script to do the comparison.

    Let's say your configuration file is /etc/my_application.conf and it looks like this:

    start_time=<some value set by application on start-up>
option1=VALUE
...

    In puppet, add a file to files/ for your configuration file, that looks like:

    start_time=DummyValue
option1=VALUE
...

    Then, use a manifest that deployes the file to an alternate location, and if changes exist, triggers a copy that then triggers the service, like so:

    file { '/etc/my_application.staging.conf':
  ensure => present,
  source => 'puppet:///modules/my_application/my_application.conf',
  owner  => ...
  notify => Exec['install-my_application.conf'],
}

exec { 'install-my_application.conf':
  refreshonly => true,
  command     => '/bin/cp /etc/my_application.staging.conf /etc/my_application.conf',
  notify      => Service['my_application'],
}

service { 'my_application':
  ...
}

    This allows you to restart on new configuration changes, but will not restart the service if my_application.conf is modified locally. This isn't a perfect solution because it does not save you from local modifications, but hopefully you can manage those with permissions and a clear warning at the top of the configuration file.

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