QEMU guest agent not available in OpenStack Nova image

[joseph-long]

I built an OpenStack VM image using https://github.com/NixOS/nixpkgs/blob/master/nixos/maintainers/scripts/openstack/nova-image.nix (specifically nix-build '<nixpkgs/nixos>' -A config.system.build.novaImage --arg configuration "{ imports = [ <nixpkgs/nixos/maintainers/scripts/openstack/nova-image.nix> ]; }") and the resulting image does not have qemu-ga available.

The administrators of the OpenStack deployment I'm using tell me this is essential, so I am looking at how to make it available. It seems like the qemu-ga binary is made available by installing qemu itself, though e.g. Gentoo's qemu-guest-agent ebuild seems to build only the guest agent.

If the guest agent is indeed required for things like snapshotting Nova VMs, it seems like nova-image.nix should ensure qemu is installed and a systemd unit created to start qemu-ga.

Technical details

• system: "x86_64-linux"
• host os: Linux 4.9.77, NixOS, 17.09.2816.ae24fad5abf (Hummingbird)
• multi-user?: no
• sandbox: yes
• version: nix-env (Nix) 1.11.16
• channels(root): "nixos-17.09.2816.ae24fad5abf"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs

[joseph-long]

Workaround

enable-qemu-guest-agent.nix

{config, pkgs, ...}:
{
  config = {
    # boot.kernelParams = [ "console=ttyS0" ];  ## Unclear if I can't see the console in the web UI because I'm missing this, or some other reason.
    environment.systemPackages = [ pkgs.qemu ];
    systemd.services.qemu-guest-agent = {
      description = "Run the QEMU Guest Agent";
      path = [ pkgs.qemu ];
      script = "qemu-ga";
      serviceConfig = {
        Restart = "always";
        RestartSec = 0;
      };
    };
    services.udev.extraRules = ''SUBSYSTEM=="virtio-ports", ATTR{name}=="org.qemu.guest_agent.0",  TAG+="systemd" ENV{SYSTEMD_WANTS}="qemu-guest-agent.service"'';
  };
}

then the command to build the image becomes

nix-build '<nixpkgs/nixos>' -A config.system.build.novaImage --arg configuration "{ imports = [ <nixpkgs/nixos/maintainers/scripts/openstack/nova-image.nix> ./enable-qemu-guest-agent.nix ]; }"

[teto]

I would like to install qemu-agent in libvirtd images for nixops too. I believe it deserves its own name qemu-agent even if it's just an alias to qemu.

[stale]

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