Nixpkgs: libvirtd: impossible to add hooks

[kliu128]

Issue description

Placing files in /etc/libvirt/hooks as is normal has no effect. It seems that the libvirt package is built with $(out)/var/lib as sysconfdir, and hooks are run from the sysconfdir folder.

Steps to reproduce

Place a script designed to run on vm start in /etc/libvirt/hooks.

Technical details

• system: "x86_64-linux"
• host os: Linux 4.19.2, NixOS, 19.03.git.4f1a831 (Koi)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.1.3
• channels(root): ""
• nixpkgs: /etc/nixos/nixpkgs

[emmanuelrosa]

Which makes the most sense:

1. Have libvirtd execute hooks from /etc/libvirt/hooks (or another location outside of the Nix store).
2. Have configuration options which can be used from configuration.nix to set up the hooks.

[volth]

Which makes the most sense:

. Have libvirtd execute hooks from /etc/libvirt/hooks (or another location outside of the Nix store).

. Have configuration options which can be used from configuration.nix to set up the hooks.

Both can work simulteniously

libvirt is to read /etc/libvirt/hooks

and libvirt nixos module could have hooks option which unfolds into
environment.etc."libvirt/hooks/blablabla".text = ...

[kliu128]

Yes, I agree -- that's what I was thinking as well.

[stale[bot]]

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[alexbakker]

This is still important to me.

[Technical27]

For anyone stumbling on this issue, put your hooks at /var/lib/libvirt/hooks

[adamlwgriffiths]

The issue is, you can't do that simply with configuration.nix, I believe it requires a custom builder or just manually dumping the files there.
I could be very wrong, but I can't see anything in Nix that let's me easily make a file in configuration.nix.

I'm also having limited success in getting the hooks to work manually, it seems you need to restart libvirt/qemu for the hooks to be detected, so just writing the files manually doesn't seem to do anything without restarting the service / system.

Having the hooks exposed for a VM definition or libvirt globally would be helpful here.