how to define a general mount point in docker compose

问题:

I would like to define a general mount volume - along with all the options I would like to have it associated - that can be reused across multiple services. In fact, I'm developing a project which uses the same source for several microservices. That way, the volume will be simpler to manage and modify.

To start off, I used the old way which took advantage of volumes_from:

shared:   image: phusion/baseimage    volumes:     - ./code:/var/www/html  nginx:   build: docker/nginx   ports:     - "8080:80"   links:     - php   volumes_from:     - shared 

This works, but I had to define a shared service to make it work. As of the 3.0 version, volumes can be used, so I would like to define a general volume and use it into my nginx service, but I'm not finding the right syntax:

version: '3.3'  volumes:   vol_test:     type: bind     source: ./code     target: /var/www/html     volume:       nocopy: true  services:   nginx:     build: docker/nginx     ports:       - "8080:80"     volumes:       - vol_test 

Update

I've found that defining a volume the way I want could not be possible, since the following definition:

volumes:   data-volume:     type: bind     source: ./code     target: /var/www/html     volume:       nocopy: true 

will produce this output when calling docker-compose up:

ERROR: The Compose file './docker-compose.yml' is invalid because: volumes.data-volume value Additional properties are not allowed ('volume', 'source', 'type', 'target' were unexpected) 

I guess I still have to use the volumes_from way then. Can anybody confirm that?

回答1:

You do not have to use volume_from anymore. Form https://docs.docker.com/compose/compose-file/#volumes:

But, if you want to reuse a volume across multiple services, then define a named volume in the top-level volumes key. Use named volumes with services, swarms, and stack files.

They even specifically address your issue:

Note: The top-level volumes key defines a named volume and references it from each service’s volumes list. This replaces volumes_from in earlier versions of the Compose file format. See Use volumes and Volume Plugins for general information on volumes.

So, for a MWE I defined an empty volume and referenced it in two services. This is the compose file:

version: '3.3'  volumes:   vol_test:  services:   reader:     image: ubuntu     tty: true     command: bash -c "sleep 1; cat /volume/file;exit 0"     volumes:       - vol_test:/volume    writer:     image: ubuntu     tty: true     command: bash -c "date | tee /volume/file; exit 0"     volumes:       - vol_test:/volume 

This gives us the following behavior:

$ date; docker-compose up So 27. Aug 11:54:13 CEST 2017 Creating network "dockercomposetest_default" with the default driver Creating dockercomposetest_writer_1 ...  Creating dockercomposetest_reader_1 ...  Creating dockercomposetest_writer_1 Creating dockercomposetest_reader_1 ... done Attaching to dockercomposetest_writer_1, dockercomposetest_reader_1 writer_1  | 27 09:54:15 UTC 2017 reader_1  | 27 09:54:15 UTC 2017 Gracefully stopping... (press Ctrl+C again to force) 

回答2:

I can confirm your observation: If you want to mount a host directory, you'll have to use the bind mount syntax.

文章来源: how to define a general mount point in docker compose