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Accepted
gnarf
Asked: 2009-09-10 13:01:47 +0800 CST

Puppet: Test if Resource is defined, or create it

  • 772

I've been trying to figure out a way to test if a resource is already defined in another file, and if not create it? A quick example:

  if File[$local_container] {
    alert("Testing - It existed $local_container")
  } else {
    file{ "$local_container":
      ensure => directory,
    }
  }

However - File[$local_container] always seems to evaluate to true. Is there a way to do this?

puppet

4 Answers

  1. Do you mean "test if a resource is already defined"? If you define a resource (ie, file {}, etc) Puppet will create what you're describing if doesn't already exist (assuming you pass ensure => present, of course).

    To check if a resource is already defined in the catalog or not:

    mark-draytons-macbook:~ mark$ cat test.pp 
file { "/tmp/foo": ensure => present }

if defined(File["/tmp/foo"]) {
  alert("/tmp/foo is defined")
} else {
  alert("/tmp/foo is not defined")
}

if defined(File["/tmp/bar"]) {
  alert("/tmp/bar is defined")
} else {
  alert("/tmp/bar is not defined")
}

mark-draytons-macbook:~ mark$ puppet test.pp 
alert: Scope(Class[main]): /tmp/foo is defined
alert: Scope(Class[main]): /tmp/bar is not defined
notice: //File[/tmp/foo]/ensure: created

    Note: defined() is dependent on parse order.

    • 15
  2. Best Answer

    The better way of doing this is by making use of ensure_resource function from puppetlabs stdlib

    It takes a resource type, title, and a list of attributes that describe a resource as parameters.

    say you have test case to only create the resource if it does not already exist-

    ensure_resource('package', 'test-pkg', {'ensure' => 'present'})
    • 10

  3. Or....

    unless File["${local_container}"] {
  file{ "${local_container}":
     ensure => directory,
  }
}

    And do keep an eye on those quotes and curly braces....

    • 2

  4. simply,

    file{ "$local_container":
  ensure => directory,
  replace => false,
}
    • -2