Allow to specify multiple layers for services

[samoht]

Currently we can specify multiple layers for the init image, but not for onboot or services images. Would be great to allow this as well.

[rn]

Could you elaborate on the use case?

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On 21 Jun 2017, at 12:39, Thomas Gazagnaire ***@***.***> wrote: Currently we can specify multiple layers for the init image, but not for onboot or services images. Would be great to allow this as well. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[MagnusS]

My use case is adding binaries to an existing service without having to rebuild/modify the whole image. For Docker for Mac we need transfused to talk to osxfs, vpnkit-expose-port as a userland proxy and an iptables binary to workaround a swarm issue inside docker-ce. We added vpnkit-expose-port to the docker-ce image directly, but the other binaries are DfM specific and osxfs is not open source yet so this doesn't seem like a possible option.

Currently I think the only alternative way to do this is to use init-containers to put the binaries in a temporary location and then bind mount them into the target service - or bind mount them from a different service using the path (which is not really supported and will break soon).

[justincormack]

There is basically no way we can do this once we switch over to image store, as you just get to unpack one image, and then add bind mounts. As Docker build has perfectly good ways of adding layers to images I would use that, and simply extend the existing base images, although the bind mount thing is also possible.

We do want to make a build tool (to replace the package Makefiles) and this could be a feature for that in future, but its not really possible now, so closing.