There are 2 ways to use drush. The first one is install drush in drupal container. Every time you need to run drush, you ssh drupal container and run the command from that. The second one is to pull the drush image and run the drush command with "docker run".
Let's have a look at the first way. If you are using Drupal 7, you may install drush 6 in your Drupal container by adding the followings into Dockerfile.
# Install drush RUN mkdir -p /usr/src/drush WORKDIR /usr/src/drush RUN curl -OL https://github.com/drush-ops/drush/archive/6.6.0.tar.gz RUN tar -xvf 6.6.0.tar.gz --strip-components=1 RUN rm 6.6.0.tar.gz RUN chmod u+x ./drush RUN ln -s /usr/src/drush/drush /usr/bin/drush
Every time you run drush command, you need to ssh to drupal container by the command below:
# ssh to container docker exec -it drupalchilli_web_1 bash
Apparently you need to replace "drupalchilli_web_1" with your container name. After that, go to the drupal root directory and run drush command.
The second way won't require Dockerfile change. You just need to docker pull drush image by the following command. For this case, we are downloading a specific version drush 8.
docker pull drush/drush:8
To execute Drush directly, run the container with docker run, mounting the /app volume:
docker run -v $(pwd):/app drush/drush:8 status