June 10, 2011

Bulk view

Managing configuration changes in Drupal

One of our clients asked if we had any tips for documenting and managing Drupal configuration, modules, versions, settings, and so on. She wrote, “It’s getting difficult to keep track of what we’ve changed, when, for that reason, and what settings are in that need to be moved to production versus what settings are there for testing purposes.” Here’s what works for us.

Version control: A good distributed version control system is key. This allows you to save and log versions of your source code, merge changes from multiple developers, review differences, and roll back to a specified version. I use Git whenever I can because it allows much more flexibility in managing changes. I like the way it makes it easy to branch code, too, so I can start working on something experimental without interfering with the rest of the code.

Issue tracking: Use a structured issue-tracking or trouble-ticketing system to manage your to-dos. That way, you can see the status of different items, refer to specific issues in your version control log entries, and make sure that nothing gets forgotten. Better yet, set up an issue tracker that’s integrated with your version control system, so you can see the changes that are associated with an issue. I’ve started using Redmine, but there are plenty of options. Find one that works well with the way your team works.

Local development environments and an integration server: Developers should be able to experiment and test locally before they share their changes, and they shouldn’t have to deal with interference from other people’s changes. They should also be able to refer to a common integration server that will be used as the basis for production code.

I typically set up a local development environment using a Linux-based virtual machine so that I can isolate all the items for a specific project. When I’m happy with the changes I’ve made to my local environment, I convert them to code (see Features below) and commit the changes to the source code repository. Then I update the integration server with the new code and confrm that my changes work there. I periodically load other developers’ changes and a backup of the integration server database into my local environment, so that I’m sure I’m working with the latest copy.

Database backups: I use Backup and Migrate for automatic trimmed-down backups of the integration server database. These are regularly committed to the version control repository so that we can load the changes in our local development environment or go back to a specific point in time.

Turning configuration into code: You can use the Features module to convert most Drupal configuration changes into code that you can commit to your version control repository.

There are some quirks to watch out for:

  • Features aren’t automatically enabled, so you may want to have one overall feature that depends on any sub-features you create. If you are using Features to manage the configuration of a site and you don’t care about breaking Features into smaller reusable components, you might consider putting all of your changes into one big Feature.
  • Variables are under the somewhat unintuitively named category of Strongarm.
  • Features doesn’t handle deletion of fields well, so delete fields directly on the integration server.
  • Some changes are not exportable, such as nodequeue. Make those changes directly on the integration server.

You want your integration server to be at the default state for all features. On your local system, make the changes you want, then create or update features to encapsulate those changes. Commit the features to your version control repository. You can check if you’ve captured all the changes by reverting your database to the server copy and verifying your functionality (make a manual backup of your local database first!). When you’re happy with the changes, push the changes to the integration server.

Using Features with your local development environment should minimize the number of changes you need to directly make on the server.

Documenting specific versions or module sources: You can use Drush Make to document the specific versions or sources you use for your Drupal modules.

Testing: In development, there are few things as frustrating as finding you’ve broken something that was working before. Save yourself lots of time and hassle by investing in automated tests. You can use Simpletest to test Drupal sites, and you can also use external testing tools such as Selenium. Tests can help you quickly find and compare working and non-working versions of your code so that you can figure out what went wrong.

What are your practices and tips?

2011-06-09 Thu 12:25