Docker.github.io: network_mode: "service:[service name]" not adequately documented.

[vinilneves]

@ the docs it reads

Network mode. Use the same values as the docker client --network parameter, plus the special form service:[service name].

But I can't find anything that clearly states what it's supposed to do, just guesses and vague answers.

Same as https://github.com/docker/docker.github.io/issues/5325
But someone closed it and said "feel free to reopen it" but ignored when people asked to reopen.

[beaufrusetta]

I'm currently using network_mode: service: <service_name> in a demo project I'm working on, and from what I can gather, it allows you to define a host container (that connects to a typical docker network), and then you can have 1 or more containers attach to the network stack of the host container.

Useful for service mesh proxy handing with apps running in containers.

Outside of that, I haven't used it otherwise.

[cecilphillip]

I'm also looking for some documentation on the details of how this feature works. I'm seeing it used in other placements, but I really don't understand the implications of this setting 🤷🏾‍♂️

[wutr]

It's pretty vague, but I believe (by reading both the Docker CLI and COMPOSE specification documentation) it is down to docker-compose implementing services which it can reference by name.

Docker CLI references containers directly (by name or id), whereas docker-compose uses services (which as far as I know, under the hood will be translated into containers).

Docker CLI states:

Network: container

With the network set to container a container will share the network stack of another container. The other container’s name must be provided in the format of --network container:<name|id>.

And the COMPOSE specification states:

network_mode

network_mode set service containers network mode. Available values are platform specific, but Compose specification define specific values which MUST be implemented as described if supported:

none which disable all container networking
host which gives the container raw access to host's network interface
service:{name} which gives the containers access to the specified service only

    network_mode: "host"
    network_mode: "none"
    network_mode: "service:[service name]"

I read this as if it implements this on top of the Docker CLI --network options. The service:[name] option is additional and seems to have the same effect as --network container:[name], except that you can refer to a service as defined in a docker-compose file, rather than having to explicitly state the container name.