Docker Compose how to extend service with build to

问题:

Having a base docker-compose.yml like the following:

version: '2'
services:
  web:
    build: .
...

How can I extend it to use an image instead?

docker-compose.prod.yml

version: '2'
services:
  web:
    image: username/repo:tag

Running it with docker docker-compose -f docker-compose.yml -f docker-compose.prod.yml up still promps:

Building web
Step 1/x : FROM ...

I tried with docker-compose -f docker-compose.yml -f docker-compose.prod.yml up --no-build:

ERROR: Service 'web' needs to be built, but --no-build was passed.

I'm expecting the "Pulling from name/repo message" instead. Which options do I have? Or do I need to create a complete duplicate file to handle this slight modification?

回答1:

Omit the build on the base docker-compose.yml, and place it in a docker-compose.override.yml file.

When you run docker-compose up it reads the overrides automatically.

Extracted from the Docker Compose Documentation.

Since your docker-compose.yml file must have either build or image, we'll use image that has less priority, resulting in:

version: '2'
services:
  web:
    image: repo
[...]

Now let's move onto docker-compose.override.yml, the one that will run by default (meaning docker-compose up or docker-compose run web command).

By default we want it to build the image from our Dockerfile, so we can do this simply by using build: .

version: '2'
services:
  web:
    build: .

The production one docker-compose.prod.yml run by using docker-compose -f docker-compose.yml -f docker-compose.prod.yml up will be similar to this one, excepting that in this case we want it to take the image from the Docker repository:

version: '2'
services:
  web:
    image: repo

Since we already have the same image: repo on our base docker-compose.yml file we can omit it here (but that's completely optional).