Override EXPOSE from parent Dockerfile

[yukw777]

Sometimes when you create a Dockerfile from another "parent" Dockerfile, you want to use new port mappings that are different from those from the parent Dockerfile. For example, in the parent Dockerfile, I expose port 22 for ssh, but in a child Dockerfile, I want to close it up and use port 5555 instead. I'm imagining something like this:

// parent
EXPOSE 22``

// child
FROM parent
// just close port 22
CLOSEPORT 22

or

// child
FROM parent
// just close all the ports
CLOSEPORT``

[SvenDowideit]

CLOSEPORT isn't exactly the opposite of EXPOSE, but then, OPENPORT would probably be a better INSTRUCTION

what about Apache.conf style?

EXPOSE -22 +5555

[yukw777]

OPENPORT vs CLOSEPORT makes sense. I like the Apache style too for its conciseness. I think we should go with the one that's easier to implement.

[joelreymont]

I'll take it.

[crosbymichael]

@yukw777 @SvenDowideit

What if I don't want people to override the settings that I specify in my images? Shouldn't the parent image dictate and child images extend?

[joelreymont]

EXTEND OFF in the parent Dockerfile?

A new verb, not implemented yet ;-).

[yukw777]

@wagerlabs @crosbymichael

Maybe PORTFREEZE? EXTEND OFF sounds like you can't do anything in the child.

[shykes]

This seems to be a generic problem: resetting image properties to drop the inheritance and start from scratch. This applies to expose but also to cmd, entrypoint, volume and so on.

I would prefer seeing a generic solution to this problem.

[shykes]

Closing in favor of the more generic #3465

[vipinvkmenon]

https://stackoverflow.com/questions/67951182/port-setting-of-docker-images-in-cloudfoundry