Mount a volume in docker-compose conditionally

docker docker-compose docker-volume
fxmasa picture fxmasa · Jan 21, 2017 · Viewed 13.1k times · Source

I have a docker-compose.yml configuration. In one of the containers there is a Tomcat server and it has some default .war file deployed in webapps directory.

I want to have an ability to pass (override) the war archive to be deployed by some which resides on the host machine. I think the best would be to have ability somehow switch / override starting docker-compose: as a default, I want to run the webapp (war file) which is inside the container, but I want to have a possibility to mount a directory from my host (for example during development / debugging) if need be.

Currently, I have the following line in my docker-compose.yml, which is commented out if I need the default.

volumes:
# By default, there is the latest version of the application already present in the container
# If you want to provider the container with your own .war file, uncomment the following line
# - ./application/webapps:/usr/local/tomcat/webapps

Is there a better way how to achieve that?

Answer

dgulabs picture dgulabs · Jul 5, 2017

Instead of (not) mounting a volume commenting out that line, I would use https://docs.docker.com/compose/extends/#example-use-case to run a service extension that specifies a volume.

I do this to tackle two different problems:

  • I don't specify a volume when the docker image is meant to run in production and has all the necessary files bundled in it.
  • I specify a volume during development, to check live changes.

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