This article outlines a few open source alternatives to MCollective that are supported in the latest version of open source Puppet. MCollective is a framework for building server orchestration or parallel job-execution systems. As of Puppet agent 5.5.4, MCollective is deprecated and has been fully removed as of Puppet 6.
Bolt is an open source orchestration tool that helps you make on-demand changes to remote targets such as servers, network devices, and cloud services.
The Choria Project allows you to continue to use MCollective through a compatibility framework capable of running Mcollective agents.
Rundeck is an open source automation service with a web console, command line tools and a WebAPI. It lets you run automation tasks across a set of nodes.