Extends puppet-lint to ensure all template functions expand a single file, rather than unexpectedly concatenating multiple template files in to a single string.

There is a slightly obscure difference in the way that puppet handles multiple file names when calling the file or template functions. In the case of the file function it will return the contents of the first file found from those given, skipping any that don’t exist. The template function on the other hand will evaluate all of the specified templates and return their outputs concatenated into a single string.

This is very rarely what you want. Assuming absent_file is, well absent, and real_file is in the correct place this will return the content of real_file.

class multi_templated_file {
  file { '/tmp/symbolic-mode':
    content => file('mymodule/absent_file.erb', 'mymodule/real_file.erb'),
  }
}

However if both of these files exist then the contents will be concatenated and the combination of all given files will be returned to content.

class multi_templated_file {
  file { '/tmp/symbolic-mode':
    content => template('mymodule/first_file.erb', 'mymodule/second_file.erb'),
  }
}

If you do want to select from multiple templates then puppet-multitemplate will give you a new function that behaves as you'd expect.

To use this plugin add the following line to your Gemfile

gem 'puppet-lint-concatenated_template_files-check'

and then run bundle install.

This plugin provides a new check to puppet-lint.

calling "template" with multiple files concatenates them into a single string

You can find a list of my puppet-lint plugins in the unixdaemon puppet-lint-plugins repo.

Dean Wilson

• MIT