Rexfile foundations

Running ad-hoc commands as shown in Minimum Viable Rex provides a good way to start benefiting from Rex, the friendly automation framework. Then sometimes we have to repeat our typical procedures. Other times it would work best if we could enable others to follow the same steps.

Just like GNU Make uses a Makefile to describe actions, Rex uses a Rexfile to describe our common procedures as code through the following foundational elements:

dependencies
configuration
inventory
authentication
tasks
arbitrary Perl code

While we may treat most elements optional depending on the use case, let’s take an initial look at each.

Minimum Viable Rex

We consider enabling graceful bootstrapping as one of our main guiding principles around Rex, the friendly automation framework.

While our How to get started with Rex page provides a good initial set of concepts, I wondered about the minimal set of features that already proves useful in practice. I find this especially interesting when using Rex from a cronjob or in a CI/CD pipeline.

Let’s see what I found through this exercise in minimalism.

Perl basics for Rex

Rex, the friendly automation framework does not expect much previous programming or Perl experience, though knowing a few foundational elements may go a long way.

While we provide a Just enough Perl for Rex page on our website, I often find myself sharing my own experience about getting started with Perl.

I decided to write my own take about the basics from a Rex perspective, and collect further resources I keep recommending or referring to.

Let’s see what I considered useful when I started out.

Installing Rex

We briefly describe the different ways to install Rex, the friendly automation framework on the Get Rex page of our website, as well as in the Installation section of our README:

Install from the Comprehensive Perl Archive Network (CPAN)
Use standard, native package managers
Build from source code

Depending on the situation at hand, one of these often fit better than the rest.

Let’s go through the available options in more detail to help choosing the best match.

Virtues of Rex

We follow a set of guiding principles while developing Rex, the friendly automation framework:

Use a programming language
Empower users through trust
Enable graceful bootstrapping

While we summarize these concepts briefly on our website, I consider it worthwhile to elaborate on the underlying details.

Let’s take a closer look at why we find these choices important.