restart behavior when using network_mode: service

[nicks]

Repro Steps

• Use this Compose file:

services:
  pause:
    image: busybox
    command: "sleep infinity"
    ports:
    - 8800:8800
  bba:
    network_mode: "service:pause"
    image: busybox
    command: "sh -c 'echo ok > index.html && busybox httpd -f -p 8800'"
    depends_on:
    - pause

• docker compose up -d
• curl localhost:8800 -> returns "ok"
• docker compose restart pause
• curl localhost:8800

Expected Result

Server returns "ok"

Actual Result

Unable to connect

Additional context

Sometimes I work with services that need to speak to each other on localhost. So I use Pod-like networking so that all my containers can reach each other. There's a pause container that sets up the network namespace, and the other compose services join to that pause container. That's what this compose file is implementing.

But suppose I want to expose a new port on the network. I add it to the pause service and run docker compose restart pause.

Oops! everything is now broken, because bba's network got disconnected from the pause container.

If I restart bba, the container works again.

I'm not sure what feature I'm actually asking for here. Maybe we should auto-restart 'bba' when the pause container restarts? Not sure.

[edit - rewrote the ticket to be a bit more structured]

[nicks]

(this is on compose 2.15.1)

(also, it took me quite a while to figure out why my containers were randomly breaking, though it made sense once i figured out the repro case)

[melyux]

@ndeloof Does that change apply to the case where the first container is restarted using autoheal? Your doc says:

"This applies to an explicit restart controlled by a Compose operation, and excludes automated restart by the container runtime after container died."

[systemmonkey42]

Hi,

I realise this is an old issue, but I wondered about this

• restart: when true a Compose implementation MUST restart service after dependent service has been restarted.

vs

• restart: when true a Compose implementation MUST restart this service after updates to the dependency service.

If a dependent service restarts because of failure, exit, termination or "autoheal" as mentioned above, the service which depends on it, should also be restarted.

I notice it currently only applies after a manual docker-compose-restart or as the result of a configuration change.

In my case, the "depends_on" is accompanied by a "network_mode: service:<dependent_service>", which means the
container MUST be restarted after the dependent container restarts or all network connectivity is lost.

Is there a way to express this requirement in the current implementation?

Thanks

[ndeloof]

@systemmonkey42 compose only can manage restart triggered by an explicit command, (auto)restart after container failure is handled by docker engine, which doesn't have such a "dependencies" logic.

[systemmonkey42]

(auto)restart after container failure is handled by docker engine

Makes sense. I ended up using a simple healthcheck which determines if the default route has disappeared, combined with an autoheal container.

Thanks for the response, and sorry for the noise.