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Introducing the Dramble - Raspberry Pi 2 cluster running Drupal 8

Dramble - 6 Raspberry Pi 2 model Bs running Drupal 8 on a cluster
Version 0.9.3 of the Dramble—running Drupal 8 on 6 Raspberry Pis

I've been tinkering with computers since I was a kid, but in the past ten or so years, mainstream computing has become more and more locked down, enclosed, lightweight, and, well, polished. I even wrote a blog post about how, nowadays, most computers are amazing. Long gone are the days when I had to worry about line voltage, IRQ settings, diagnosing bad capacitors, and replacing 40-pin cables that went bad!

But I'm always tempted back into my earlier years of more hardware-oriented hacking when I pull out one of my Raspberry Pi B+/A+ or Arduino Unos. These devices are as raw of modern computers as you can get—requiring you to actual touch the silicone chips and pins to be able to even use the devices. I've been building a temperature monitoring network that's based around a Node.js/Express app using Pis and Arduinos placed around my house. I've also been working a lot lately on a project that incorporates three of my current favorite technologies: The Raspberry Pi 2 model B (just announced earlier this month), Ansible, and Drupal!

In short, I'm building a cluster of Raspberry Pis, and designating it a 'Dramble'—a 'bramble' of Raspberry Pis running Drupal 8.

Highly-Available PHP infrastructure with Ansible

I just posted a large excerpt from Ansible for DevOps over on the Server Check.in blog: Highly-Available Infrastructure Provisioning and Configuration with Ansible. In it, I describe a simple set of playbooks that configures a highly-available infrastructure primarily for PHP-based websites and web applications, using Varnish, Apache, Memcached, and MySQL, each configured in a way optimal for high-traffic and highly-available sites.

Here's a diagram of the ultimate infrastructure being built:

Highly Available Infrastructure

The configuration is similar to what many larger Drupal sites would use, and with the exception of the varnish default.vcl and the actual PHP script being deployed (in the example, it's just a PHP file that tests the rest of the infrastructure and outputs success/fail statuses), you could drop a Drupal site on the Apache servers and immediately start scaling up your traffic!

NFS, rsync, and shared folder performance in Vagrant VMs

It's been a well-known fact that using native VirtualBox or VMWare shared folders is a terrible idea if you're developing a Drupal site (or some other site that uses thousands of files in hundreds of folders). The most common recommendation is to switch to NFS for shared folders.

NFS shared folders are a decent solution, and using NFS does indeed speed up performance quite a bit (usually on the order of 20-50x for a file-heavy framework like Drupal!). However, it has it's downsides: it requires extra effort to get running on Windows, requires NFS support inside the VM (not all Vagrant base boxes provide support by default), and is not actually all that fast—in comparison to native filesystem performance.

I was developing a relatively large Drupal site lately, with over 200 modules enabled, meaning there were literally thousands of files and hundreds of directories that Drupal would end up scanning/including on every page request. For some reason, even simple pages like admin forms would take 2+ seconds to load, and digging into the situation with XHProf, I found a likely culprit:

is_dir xhprof Drupal

There are a few ways to make this less painful when using NFS (since NFS incurs a slight overhead for every directory/file scan):

Creating a contact form programmatically in Drupal 8

Drupal 8's expanded and broadly-used Entity API extends even to Contact Forms, and recently I needed to create a contact form programmatically as part of Honeypot's test suite. Normally, you can export a contact form as part of your site configuration, then when it's imported in a different site/environment, it will be set up simply and easily.

However, if you need to create a contact form programmatically (in code, dynamically), it's a rather simple affair:

First, use Drupal's ContactForm class at the top of the file so you can use the class in your code later:

use Drupal\contact\Entity\ContactForm;

Then, create() and save() a ContactForm entity using:

Midwestern Mac's Vagrant Boxes - CentOS and Ubuntu

In support of my mission to make local development easier and faster, I've released boxes for four of the most popular Linux distributions I use and see used for Drupal sites: CentOS 6/7 and Ubuntu 12.04/14.04.

Vagrant Boxes - Midwestern Mac, LLC

I've been using other base boxes in the past, but it's hard to find updated boxes (especially for newer OSes) from people or companies you can trust that are truly minimal base boxes (e.g. no extra configuration management tools or junk to kludge up my development environment!). These boxes are all minimal installs that let you bring your own configuration however you want; I typically use an Ansible playbook to build a LAMP server, or a Solr server, or an ELK server for monitoring all the other servers...

You can find all the info on the boxes (including links to the Packer/Ansible build configuration used to create the boxes) on files.midwesternmac.com, and the boxes are also available on Vagrant Cloud: geerlingguy's boxes.

Preventing yourself from accidentally breaking production with Drush

For all the sites I maintain, I have at least a local and production environment. Some projects warrant a dev, qa, etc. as well, but for the purposes of this post, let's just assume you often run drush commands on local or development environments during development, and eventually run a similar command on production during a deployment.

What happens if, at some point, you are churning through some Drush commands, using aliases (e.g. drush @site.local break-all-the-things to break things for testing), and you accidentally enter @site.prod instead of @site.local? Or what if you were doing something potentially disastrous, like deleting a database table locally so you can test a module install file, using drush sqlq to run a query?

$ drush @site.prod break-all-the-things -y
Everything is broken!                                    [sadpanda]

Most potentially-devastating drush commands will ask for confirmation (which could be overridden with a -y in the command), but I like having an extra layer of protection to make sure I don't do something dumb. If you use Bash for your shell session, you can put the following into your .profile or .bash_profile, and Bash will warn you whenever the string .prod is in one of your commands:


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