This blog post will focus on the bash programming part of implementing a promise type. To understand what custom promise types are, and how to use them, you should read the introduction first.

CFEngine 3.17.0 introduced custom promise types, which enable CFEngine users to extend core functionality and policy language in a simple way. As an example of the power and simplicity of this new feature, I will show a promise type that helps to observe a website’s status. The module which implements this promise type was written in a couple of hours.

Several months ago I started the practice of using CFEngine Enterprise and its Mission Portal UI on a daily basis to manage the connected devices in my home. To start, I brought up an old desktop machine, cfengine-hub, to use as my hub and downloaded Enterprise, which is free for use up to 25 hosts. The next step in using best practices is to deploy policy from a version control repository.