I have spent way too much time getting this to work. Here are my findings.
Like OP I never got the drush image to work on the local docker network so it seemed simpler to me to bundle drush via composer with the drupal image (see Dockerfile below).
That works somewhat, if you exec into the container you can run drush status, but it won't connect to the mysql server. There are two reasons for this:
The package mysql-client is needed to connect remotely to the database (since we are running this on a local docker network).
The mysql hostname needs to be explicitly set in the docker-compose file (or docker run command).
This is my Dockerfile:
FROM drupal:8.3.7-apache
# Install packages
RUN rm /bin/sh && ln -s /bin/bash /bin/sh && \
apt-get update && apt-get install --no-install-recommends -y \
curl \
wget \
vim \
git \
unzip \
mysql-client
# Install Composer
RUN curl -sS https://getcomposer.org/installer | php && \
mv composer.phar /usr/local/bin/composer && \
ln -s /root/.composer/vendor/bin/drush /usr/local/bin/drush
# Install Drush
RUN composer global require drush/drush && \
composer global update
# Clean repository
RUN apt-get clean && rm -rf /var/lib/apt/lists/*
The important packages are curl (obviously) and mysql-client.
And these are the relevant parts of the docker-compose.yml:
version: '3.3'
services:
drupal:
image: drupal
build: ./docker/drupal
env_file:
- ./docker/environment.env
ports:
- "8080:80"
depends_on:
- mysql
restart: always
phpmyadmin:
image: phpmyadmin/phpmyadmin:latest
volumes:
- ./docker/phpmyadmin/config.user.inc.php:/etc/phpmyadmin/config.user.inc.php
env_file:
- ./docker/intervention/environment.env
ports:
- "8080:80"
depends_on:
- mysql
restart: always
mysql:
image: mysql
build: ./docker/mysql
env_file:
- ./docker/environment.env
hostname: mysql
ports:
- 3306:3306
volumes:
- mysql-data-d8:/var/lib/mysql
restart: always
volumes:
mysql-data-d8:
Why explicitly setting the hostname works
The second problem above is particularly devilish since drush use the configuration from settings.php to connect to mysql. But the 'host' key in the databases array is interpreted differently by drupal and drush apparently. Here is the relevant section from settings.php:
$databases = array (
'default' => array (
'default' => array (
'database' => $envs['MYSQL_DATABASE'] ?? '',
'username' => $envs['MYSQL_USER'] ?? '',
'password' => $envs['MYSQL_PASSWORD'] ?? '',
'host' => 'mysql',//php_sapi_name() === 'cli' ? 'a8597b38be21' : 'mysql',
'port' => '3306',
'driver' => 'mysql',
'prefix' => 'drupal_',
'charset' => 'utf8mb4',
'collation' => 'utf8mb4_general_ci',
'namespace' => 'Drupal\\Core\\Database\\Driver\\mysql',
),
),
);
The out commented line after 'host' => 'mysql' is a previous attempt taken from another SO answer and illustrates the problem, drush use the command line server API which is different from whatever drupal uses. The alternate hostname is the hash id of the running container, which can be found by running the sql (from phpmyadmin for example):
SHOW VARIABLES WHERE Variable_name = 'hostname' (taken form this)
This value changes every time the container is updated, so to make it persist, the hostname is explicitely stated in docker-compose.yml, se above.
Edit: I've made a small project to host a drupal + drush + phpmyadmin development environment based on this: https://github.com/glaux/drupal8docker
