What Puppet function can ensure a resource is managed only once?

The function that can ensure a resource is managed only once is the "ensure" function. In Puppet, the "ensure" attribute is critical for resource declarations as it specifies the desired state of a resource. By setting the "ensure" parameter, you can designate whether a resource should be present (created), absent (removed), or in a specific state (like running or stopped for a service).

For instance, when you set a file resource with "ensure => present", Puppet will check and ensure that the file exists. If you change it to "ensure => absent", Puppet will ensure that the file is removed. This functionality inherently prevents multiple applications or states of the resource by monitoring the "ensure" state and enforcing it.

Utilizing the "ensure" attribute appropriately can significantly aid in maintaining idempotence within Puppet manifests, which means that applying the same configuration multiple times does not change the system beyond the initial application. This is essential for system administration as it eliminates redundancy and helps prevent conflicting resource states, ensuring that resources are effectively managed only once.