Nixpkgs: Declaratively running a docker image

[coretemp]

Issue description

It's not really clear to me what the workflow is for running a docker image like for example hosted on ECR. Does one need to run a systemd unit to make this work? Or is there a module where you can just input declaratively what should be running and that's it?

Technical details

NixOS 17.09, but willing to upgrade to 18.03, if needed.

[FRidh]

I think you can use config.docker-containers to specify containers to run
https://github.com/NixOS/nixpkgs/blob/release-17.09/nixos/modules/service-managers/docker.nix

[coretemp]

Thank you for answering @FRidh, but I am afraid that your answer is not concrete enough to help me.

@copumpkin The documentation of those options is not usable by me. Can you make it such that it is usable? (Include at the very least an example.)

[bachp]

@coretemp I use rkt + Systemd to run docker containers on NixOS.
As rkt doesn't have it's own process supervision it integrates nicely with NixOS services.

My config looks like this:

virtualisation.rkt = {
    enable = true;
};

systemd.services."rkt-arango" = {
    description = "ArangoDB (rkt)";
    wantedBy = [ "multi-user.target" ];
    serviceConfig = {
      Slice = "machine.slice";
      ExecStart = ''\
        ${pkgs.rkt}/bin/rkt run --insecure-options=image \
        --port=8529-tcp:8529 --set-env=ARANGO_ROOT_PASSWORD=secret \
        --volume=volume-var-lib-arangodb3,kind=host,source=/var/lib/arango-data,readOnly=false \
        --volume=volume-var-lib-arangodb3-apps,kind=host,source=/var/lib/arango-apps,readOnly=false \
        docker://arangodb \
      '';
      KillMode = "mixed";
      Restart = "always";
    };
};

[davidak]

FYI: docker-containers was an experimental feature that is removed in 18.03.

[copumpkin]

Yeah, I merged it by accident, sorry for the confusion 😄 someday I'll get enough time to do it properly

[liamdawson]

Are there any plans for a docker-containers alternative, or are we expected to roll our own management methodology? I can do that, but if NixOS can handle the logistics for me, what's the point? 😄

[benley]

I'm having a go at a fairly simple version of this in https://github.com/NixOS/nixpkgs/pull/55179

[benley]

I think we can close this now that docker-containers is back via #55179. It didn't make it into the 19.03 release but it's usable in nixos-unstable, and ought to show up in the next stable release.