Puppet: Test if Resource is defined, or create it

Solution 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.

Solution 2:

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'})

---

Solution 3:

Or....

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

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