Using Drush in a docker Drupal development environment
There are a number of ways to roll Drupal with Docker. We've been using phpdocker.io for a long time for various LAMP projects and had never looked at the Drupalised Docker images--mainly for consistency across projects. However the downside of going off campus is lack of a tuned database and difficulties using Drush.
We'd tried many approaches to this and none have worked consistently. Recently, however, we put in a bit more effort while updating an aging development stack for a long running project.
Firstly though we were striking issues with MariaDB running out of memory:
PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away:
This is a fairly common problem and fairly easy to fix: add resources to MariaDB's
my.cnf file as per the note on Drupal.org.
Not so easy to do with Docker. Here's how to do it on top of the phpdocker.io
docker-compose.yml file. Add the command containing Drupal's recommended defaults.
command: --key-buffer-size=384M --max-allowed-packet=64M --table-open-cache=4096 --read-buffer-size=2M --read-rnd-buffer-size=64M --myisam-sort-buffer-size=64M --thread-cache-size=8 --query-cache-size=32M --innodb-buffer-pool-size=384M --innodb-additional-mem-pool-size=20M --innodb-log-buffer-size=64M --innodb-lock-wait-timeout=180
The next, more difficult, challenge was getting Drush working well. Often we could get drush status working, or drush download, or drush sql-cli, with a bit of alias hacking. However it was always a bit agricultural and required switching methods to perform different actions.
The current solution, which seems to be working well at the moment, is using the drush/drush:7 image inside our docker-compose.yml file. Here's how it goes:
volumes: - .:/application
Then kill and restart docker-compose and run drush via docker-compose:
$ docker-compose run drush --uri=http://webserver --root=/application/public sql-cli
Note that URI is made up of the docker-compose web server container name and root is the docker volumes alias and any additional path.