Missing <IP>:<host_port>:<container_port> explaination docker-compose

[JoachimBose]

Is this a docs issue?

• My issue is about the documentation content or website

Type of issue

I can't find what I'm looking for

Description

The website provides very helpful information about the <host_port>:<container_port> syntax for exposing ports in Docker Compose. However, it does not seem to explain anything about the extended :<host_port>:<container_port> syntax.

Location

https://docs.docker.com/get-started/docker-concepts/running-containers/publishing-ports/

Suggestion

dd a section in the documentation that explicitly covers this syntax and includes examples of how and when it can be used. Unfortunately I am nowhere near an expert in this (hence why I tried to look it up).

Thank you! Cheers

[thaJeztah]

Thanks for reporting; there are some additional links at the bottom of the page (under "Additional resources) linking to the "published ports" section; https://docs.docker.com/engine/network/#published-ports

That said, I think there's some information spread across the documentation that we might be able to consolidate to provide a more in-depth overview of the available options, and to describe the short-form and long-form syntax

/cc @robmry @akerouanton

[akerouanton]

Indeed, port mapping became a complex subject over time and information is spread all over the place. I think we should have a dedicated page that explain how it works and the various options that can influence it, including:

• Long and short syntax
• What the label com.docker.network.bridge.host_binding_ipv4 does, and how to configure it globally
• How port folding / port expansion work
• Hairpinning and what docker-proxy does
• What the label gw_mode does

And probably more.