Deprecation Warnings From Puppet Resources

Over time parts of your puppet manifests will become unneeded. You might move a cronjob or a users in to a package or no longer need a service to be enabled after a given release. I’ve recently had this use case and had two options - either rely on comments in the Puppet code and write an out of band tool to scan the code base and present a report or add them to the puppet resources themselves. I chose the latter.

Below you’ll find a simple metaparameter (a parameter that works with any resource type) that adds this feature to puppet. As this is an early prototype I’ve hacked it directly in to my local puppet fork. Below you’ll see a sample resource that declares a deprecation date and message, the code that implements it and a simple command line test you can run to confirm it works.

# sample puppet resource using :deprecation

  file { '/ec/cron.d/remove_foos':
    ensure      => 'file',
    source      => 'puppet:///modules/foo/foo.cron',
    deprecation => '20130425:Release 6 removes the need for the foo cronjob',

  $ sudo vi puppet-3.1.1/lib/puppet/type.rb

  newmetaparam(:deprecation) do
    desc "
      Add a deprecation warning to resources.

      file { '/etc/foo':
        content     => 'Bar',
        deprecation => '20130425:We no longer need the foo'

      The deprecation comes in two parts, separated by a :
      The date is in format YYYYMMDD and the message is a free form string.

      munge do |deprecation|
        date, message = deprecation.split(':')

        # YYY MM DD - one true timestamp
        now ='%Y%m%d')

        if (now >= date)
          rsrc = "#{@resource.type.capitalize}[#{}]"

          Puppet.warning "#{rsrc} expired on #{date}: #{message}"

# command line test

$ puppet apply -e 'file { "/tmp/dep": content => "foo\n", deprecation =>
"20120425:We can remove this file after release 4" }' 
Warning: File[/tmp/dep] expired on 20120425: We can remove this file after release 4
Notice: Finished catalog run in 0.06 seconds

Using the metaparameter is easy enough, just specify ‘deprecation’ as a property on a resource and provide a string that contains the date to start flagging the deprecation on (in YYYYMMDD format) and the message puppet should show. I don’t currently fail the run on an expired resource but this is an option.

The are some other aspects of this to consider - Richard Clamp raised the idea of having a native type that could indicate this for an entire class (I’d rather use a function, but only because they are much easier to write) and Trevor Vaughan suggested a Puppet face that could present a report of the expired, and soon to be expired, code.

I don’t know how widely useful this is but it made a nice change to write some puppet code. The small size of the example will hopefully show how easy it is to extend nearly every part of puppet - including more ‘complicated’ aspects like metaparameters. Although not the relationship ones, those are horrible ;) I’ve submitted the idea to the upstream development list so we’ll see what happens.