Skip to content

Avoid using EXPOSE directive for optional ports #20

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
yvanzo wants to merge 3 commits into
base: master
Choose a base branch
from
Open

Avoid using EXPOSE directive for optional ports #20

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
984f650
Use --expose instead of EXPOSE for optional ports
yvanzo May 26, 2022
de72171
Narrow the conditions to use EXPOSE directive
yvanzo May 26, 2022
4c3103c
Refer to the below section for expose in Compose
yvanzo May 26, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 6 additions & 3 deletions Docker.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,12 @@

## `Dockerfile`

When building an image that is running some services,
use the [`EXPOSE` directive](https://docs.docker.com/engine/reference/builder/#expose),
to document which ports the services are listening to.
When building an image that will be run by one (or many) container(s) providing (the same) services,
use the [`EXPOSE` directive](https://docs.docker.com/engine/reference/builder/#expose)
with mandatory ports only,
to document which ports the services are necessarily listening to. If the image will be used to run many
containers, some of which don't listen on a port, instead use the `expose` option in
`docker-compose.yml` (see the below section for details) or the `--expose` flag to `docker run`.
Comment on lines +7 to +10
Copy link
Contributor

@alastair alastair Jan 31, 2023

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Suggested change
with mandatory ports only,
to document which ports the services are necessarily listening to. If the image will be used to run many
containers, some of which don't listen on a port, instead use the `expose` option in
`docker-compose.yml` (see the below section for details) or the `--expose` flag to `docker run`.
only when **all** containers using this image will listen on that port, to document that all services
will be listening on that port. If the image will be used to run many
containers, some of which don't listen on a port, instead use the `expose` option in
`docker-compose.yml` (see the below section for details) or the `--expose` flag to `docker run`
on only the containers which listen on the port.

Some tools ([such as the nginx proxy companion](https://github.com/nginx-proxy/acme-companion#step-3---proxied-containers))
use it to define a contract between different containers too.
Not using this directive doesn’t prevent exposing those ports to the Docker network.
Expand Down