Puppet Server: Admin API: JRuby Pool

Puppet Server contains a pool of JRuby instances. Puppet Server adds a new, experimental endpoint to the master’s HTTP API:

DELETE /puppet-admin-api/v1/jruby-pool

This will remove all of the existing JRuby interpreters from the pool, allowing the memory occupied by these interpreters to be reclaimed by the JVM’s garbage collector. The pool will then be refilled with new JRuby instances, each of which will load the latest Ruby code and related resources from disk.

If you’re developing new Ruby plugins that run on the Puppet master (functions, resource types, report handlers), you may need to force Puppet to re-load its plugins when a new version is ready to test. Killing the JRuby instances will do this, and it’s faster than restarting the entire JVM process.

Furthermore, if you are using multiple environments, this could be useful if you want to make sure that your JRuby instances are cleaned up and don’t have conflicts based on common code that appears in multiple environments.

This is an experimental feature, and as such the performance impact is unknown at this time. Also, please note that this operation is computationally expensive, and as such Puppet Server will be unable to fulfill any incoming requests until the first of the new interpreters has been initialized, which may take several seconds.


A successful request to this endpoint will return an HTTP 204: No Content. The response body will be empty.


$ curl -i --cert <PATH TO CERT> --key <PATH TO KEY> --cacert <PATH TO PUPPET CA CERT> -X DELETE https://localhost:8140/puppet-admin-api/v1/jruby-pool
HTTP/1.1 204 No Content

Relevant Configuration

Access to this endpoint is controlled by the puppet-admin section of puppetserver.conf. See the configuration page for more information.

In the example above, the curl command is using a certificate and private key. You must make sure this certificate’s name is included in the puppet-admin -> client-whitelist setting before you can use it.