ansible

The following is an excerpt from Chapter 8 of Ansible for DevOps, a book on Ansible by Jeff Geerling.

Modern infrastructure often involves some amount of horizontal scaling; instead of having one giant server, with one storage volume, one database, one application instance, etc., most apps use two, four, ten, or dozens of servers.

Many applications can be scaled horizontally with ease, but what happens when you need shared resources, like files, application code, or other transient data, to be shared on all the servers? And how do you have this data scale out with your infrastructure, in a fast but reliable way? There are many different approaches to synchronizing or distributing files across servers:

Over the course of this year, I've acquired six Raspberry Pi model 2 B computers, and configured them in a cluster (or 'bramble') so I can use them to test different infrastructure configurations, mostly for running Drupal 8. All the Ansible playbooks and instructions for building the cluster are available on the GitHub project page for the Raspberry Pi Dramble.

Each Raspberry Pi has its own RGB LED board that's wired into the GPIO pins, so they're controlled by software. I can demonstrate different ways of managing the cluster via Ansible, and I finally took the time to make a video, Ansible 101 - on a cluster of Raspberry Pi 2s, which shows how it all works together:

Ansible is coming to St. Louis—the hometown of Midwestern Mac, LLC, which runs Server Check.in!

The first-ever Ansible meetup in St. Louis, MO will be held at Riot Games' offices in downtown Clayton (yes, that Riot—the company that makes League of Legends!).

Server Check.in is sponsoring refreshments for the night, and if you're interested in coming, it starts at about 7:00 p.m. There will be Ansible T-shirts and swag, and Jeff Geerling (author of Ansible for DevOps and owner of Midwestern Mac, LLC) will give a crash course in Ansible and kick off discussion on how to get started with Ansible.

See more details on the Ansible St. Louis Meetup page.

The following is an excerpt from Chapter 7 of Ansible for DevOps, a book on Ansible by Jeff Geerling.

Most infrastructure can be managed with a custom inventory file or an off-the-shelf cloud inventory script, but there are many situations where more control is needed. Ansible will accept any kind of executable file as an inventory file, so you can build your own dynamic inventory however you like, as long as you can pass it to Ansible as JSON.

You could create an executable binary, a script, or anything else that can be run and will output JSON to stdout, and Ansible will call it with the argument --list when you run, as an example, ansible all -i my-inventory-script -m ping.

Let's start working our own custom dynamic inventory script by outlining the basic JSON format Ansible expects:

The following is an excerpt from Chapter 11 of Ansible for DevOps, a book on Ansible by Jeff Geerling. The example highlights the effectiveness of Ansible Tower for automating infrastructure operations, especially in a team environment.

Throughout this book, all the examples use Ansible's CLI to run playbooks and report back the results. For smaller teams, especially when everyone on the team is well-versed in how to use Ansible, YAML syntax, and follows security best practices with playbooks and variables files, using the CLI can be a sustainable approach.

But for many organizations, there are needs that stretch basic CLI use too far:

Edit: Many people have been asking for more technical detail, benchmarks, etc. There is much more information available on the Raspberry Pi Dramble Wiki (e.g. Power Consumption, microSD card benchmarks, etc.), if you're interested.

After the Raspberry Pi 2 model B was released, I decided the Pi was finally a fast enough computing platform (with its 4-core 900 MHz ARMv7 architecture) with enough memory (1 GB per Pi) to actually use for web infrastructure. If not in a production environment (I would definitely avoid putting the Pi into a role as a high-load 24x7x365 server), then for development and/or testing purposes. And for some fun!

On March 21, I gave a presentation on Ansible and Drupal 8 at MidCamp in Chicago. Video and slides from the presentation are embedded below:

Ansible + Drupal: A Fortuitous DevOps Match from geerlingguy

Human-readable configuration syntax. Great user experience. Designed for high availability and flexibility. Includes everything you need to achieve your development goals.