Mapping Ports?

[scottfwalter]

Is there a way map ports? For example port 8088 on my local machine, but port 80 inside the container? I looked at the how to documentation page and I did not find any info. Thanks.

[BenHall]

You should be able to solve this using socat to bind 8088 to the IP:80 of the container, similar to https://github.com/apple/container/blob/main/docs/technical-overview.md#container-to-host-networking

[scottwalter-nice]

Hopefully, a command line option will be added for a better developer experience.

[lperdereau]

Hey everyone!

I wanted to share a handy shell alias I created for forwarding ports to a container using socat. This alias simplifies the process and makes it easier to manage port forwarding with just a single command. 😅

Note: I'm note proud of it

alias container-port-forward='function _container_port_forward() {
    local container_id="$1"
    local src_port="$2"
    local dst_port="$3"
    sudo socat TCP-LISTEN:"$src_port",fork TCP:$(container inspect "$container_id" | jq -r ".[0].networks[0].address" | cut -d'/' -f1):"$dst_port"
}; _container_port_forward'

container-port-forward <containerd-id> <local-port> <container-port>

[scottfwalter]

@lperdereau nice job!

[tidbeck]

Thanks for the workaround @lperdereau! Is there any similar approach to reach a service inside the container that binds to 127.0.0.1 (as it will normally not be accessible from another IP) without modifying the image?

[jglogan]

@lperdereau Nice! Thank you for sharing that alias.

@tidbeck Sorry for the long delay, I just came back to this issue and noticed your comment.

Container-to-host networking is a slightly different problem than publishing container ports to the host. Right now that's not possible in the nice easy way that Docker, Colima, et al do it (just use host.docker.internal in the container and it magically gets your traffic to your host-based service).

We documented this limitation and the socat-based workaround is here: https://github.com/apple/container/blob/main/docs/technical-overview.md#container-to-host-networking

[jglogan]

Port forwarding (--publish/-p) will be done in two parts, to keep the PRs manageable.

#338 adds TCP and UDP forwarders.

The next PR will plumb --publish from CLI options to ContainerClient configuration to running the forwarders in SandboxService.