ensure_package existing resource detection

[Oliver Schraml]

Use Case

supported puppet modules use sometimes the ensure_package function, which leads to a duplicate declaration error if you have it already defined in another manifest which gets included during the catalog build.

Describe the Solution You Would Like

the function ensure_package could check, as it does already for the packages puppet and facter, if it is somewhere defined in the current build catalog, to allow the defined resources from the manifest to be used instead of the ensure_package function.

Describe Alternatives You've Considered

I have thought about patching the upstream puppetlabs-apt module by adding a if condition with something like if ! (defined(Package['<packagename>']) { but that would mean on each update of the modules I would need to take care of getting back my change.
Another solution could be, that I place an if condition in front of the include command based on the puppet role which is used.
Both are not a really nice to have, but would work.

Additional Context

Found it while using the puppetlabs-apt module which uses ensure_package(['gnupg']), also I have a package resource which is already defined in an existing manifest. As soon both are used for the same catalog build, it runs into a duplicate declaration error.

puppetlabs-apt: v8.4.1
puppetlabs-stdlib: v8.2.0

  package { 'gnupg':
    ensure  => installed,
    require => Exec['apt_update'],
  }

Error:

Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Error while evaluating a Resource Statement, Duplicate declaration: Package[gnupg] is already declared at (file: /data/puppet/environments/production/modules/apt/manifests/init.pp, line: 365); cannot redeclare (file: /data/puppet/environments/production/modules/defaults/manifests/packages/gnupg.pp, line: 6) (file: /data/puppet/environments/production/modules/defaults/manifests/packages/gnupg.pp, line: 6, column: 3) on node puppettest1.internal.testdomain

With this extension of ensure_package, puppet would make sure that the defined attributes on the package resource are getting used instead of "just" an ensure => present/installed as things like that are sometimes required.

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[John Bond]

i dont think this is something that would happen as it would be a massive change to the current functionality and affect way to many things. I think that the best way to do resolve this is for you to also use ensure_packages in your own code.

to maintain the dependency you can use chaining e.g.

ensure_packages(['gnupg'])
Exec['apt_update'] -> Package['gnupg']
# or perhaps for all packages
Exec['apt_update'] -> Package<| |>

[Alexander Fisher]

Part of your issue is probably this (IMO) completely unnecessary breaking change that was introduced in 8.0.0. #1196

'fixing' that is still somewhere on my todo list.