Does specifying ports in a docker-compose file override the ports exposed in a Dockerfile?

Question

If I have a Dockerfile in a folder called foo with the following line:

EXPOSE 80

And I have a docker-compose that builds the container like this:

services:
  foo:
    build: foo
    ...
    ports:
     - "5000:5000"

On the host machine, I'm only able to reach port 5000, while 80 refuses to connect.

So what exactly happens? Does docker-compose completely override the Dockerfile's EXPOSE commands? Does port 80 get exposed to only other containers on the internal network?

(I'm not really asking because I have a problem -- I just saw that the EXPOSE 80 still happened to be in my Dockerfile and I'm curious if it affects anything.)

Possible duplicate of [What is the difference between "expose" and "publish" in Docker?](https://stackoverflow.com/questions/22111060/what-is-the-difference-between-expose-and-publish-in-docker) — David Maze, Oct 02 '18 at 23:12

score 3 · Accepted Answer · answered Oct 02 '18 at 20:26

3

If you are using docker-compose up, then the dockerfile ports will be overridden. When you use docker run, the ports mentioned in dockerfile will be exposed.

answered Oct 02 '18 at 20:26

prisar

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Thanks, looks like I can remove some muck from my Dockerfile then! – Leon Overweel Oct 02 '18 at 20:30
1

Yes, you can only keep port mappings in docker compose file. – prisar Oct 02 '18 at 20:32

Does specifying ports in a docker-compose file override the ports exposed in a Dockerfile?

1 Answers1