qemu-guest-agent: init module #39099

teto · 2018-04-18T06:30:58Z

Motivation for this change

Not finished but I could use feedback on what to provide as an option or not. The Qemu guest agent allows out of band communications with Qemu VMs and allows for fancy things.

Ref:
NixOS/nixops#922
#34722

Things done

Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
Built on platform(s)
- NixOS
- macOS
- other Linux distributions
Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
Tested execution of all binary files (usually in ./result/bin/)
Fits CONTRIBUTING.md.

ikervagyok · 2018-04-18T09:48:05Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Whether to enable the dspam spam filter.";


copy paste?

right, fixed locally

xeji · 2018-04-19T13:45:47Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+        SUBSYSTEM=="virtio-ports", ATTR{name}=="org.qemu.guest_agent.0", TAG+="systemd" ENV{SYSTEMD_WANTS}="qemu-guest-agent.service"
+      '';
+
+      environment.systemPackages = [ pkgs.qemu ];


This is problematic:

It makes the guest depend on full qemu although it just needs the guest-agent.

It's a hard reference to standard qemu. We have several variants like qemu_test and qemu_kvm, and it is difficult to tell from the guest config which one the host will use to run the vm. So this may build/download an additional qemu version ... just for the guest-agent.

I think the cleanest solution is to create a separate small qemu-guest-agent package (as many other distros do), no variants needed for this.

I agree, in fact I had started writing the package qemu-agent before realizing it was already in the package. I am not sure how easy it is to generate just the Qemu agent, I wouldn't mind someone else doing it (or I can try later but I am short on time this month).

I'll try and package qemu-guest-agent, wanted to do that anyway.

Creating a separate package turned out to be rather messy, so I put the quest agent in a separate output in #39212. With this merged, you can just use qemu.ga in your module.

thanks for the agent
Regarding your comment

It's a hard reference to standard qemu. We have several variants like qemu_test and qemu_kvm, and it is difficult to tell from the guest config which one the host will use to run the vm. So this may build/download an additional qemu version ... just for the guest-agent.

How do you propose to solve it ?
Should I use another option qemuPackage ?

Should I use another option qemuPackage ?

You could do that but not sure I'm not sure that's necessary. If you use qemu.ga in the guest config, it should only install the small ga output.

xeji · 2018-04-19T13:48:33Z

nixos/modules/virtualisation/qemu-vm.nix

@@ -343,6 +343,15 @@ in
            (<literal>virtio</literal> or <literal>scsi</literal>).
          '';
        };
+
+      guestAgent =


For consistency with other options I suggest calling this guestAgent.enable or useGuestAgent.
Also, spelling should be unified beween guestAgent for one option and qemu-guest-agent for the other.

Ig uess I'll follow the pattern virtualboxGuest, hypvGuest with qemuGuest (https://nixos.org/nixos/options.html#guest)

teto · 2018-04-26T10:08:37Z

@xeji I updated the PR hoping that's cleaner.

xeji · 2018-04-26T10:18:40Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Whether to enable the dspam spam filter.";


Didn't you fix this before?

right, I fucked up the merge of the changes from different branches sorry

xeji · 2018-04-26T10:20:09Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+
+      systemd.services.qemu-guest-agent = {
+        description = "Run the QEMU Guest Agent";
+        path = [ pkgs.qemu ];


Is this necessary? you have the full path to the binary in ExecStart=

nope removing it

xeji · 2018-04-26T10:21:08Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+        description = "Run the QEMU Guest Agent";
+        path = [ pkgs.qemu ];
+        serviceConfig = {
+          ExecStart = "${pkgs.kvm}/bin/qemu-ga";


I suggest to use pkgs.qemu.ga or pkgs.kvm.ga here as discussed earlier. Should be consistent with what you use in environment.systemPackages above.

I suppose I could get rid of the environment.systemPackages too

teto · 2018-04-26T11:34:25Z

Once again xD ?

xeji · 2018-04-26T16:46:24Z

nixos/modules/virtualisation/qemu-guest-agent.nix

+      systemd.services.qemu-guest-agent = {
+        description = "Run the QEMU Guest Agent";
+        serviceConfig = {
+          ExecStart = "${pkgs.kvm}/bin/qemu-ga";


Please use ${pkgs.kvm.ga}/bin/qemu-ga. The guest needs only the guest agent, not the full package.

Allow out of band communication between qemu VMs and the host. Useful to retrieve IPs of VMs from the host (for instance when libvirt can't analyze DHCP requests because VMs are configured with static addresses or when there is connectivity default).

teto · 2018-05-01T01:19:36Z

right; fixed.

teto · 2018-05-08T02:50:08Z

@xeji is that ok (sorry for the repeated mistakes) ?

xeji · 2018-05-08T20:35:57Z

Looks good. Let me try it locally before merging.

vobloeb · 2023-09-26T21:15:20Z

Starting via udev (on device appearance) results in the service does not start on switch-to-configuration switch being added to the configuration.

It may have a sense to run the service always, using casual wantedBy = [ "multi-user.target" ]; instead of udev

teto mentioned this pull request Apr 18, 2018

[WIP] Improve networking options for libvirtd target NixOS/nixops#922

Closed

GrahamcOfBorg added 6.topic: nixos 8.has: module (update) 10.rebuild-darwin: 0 10.rebuild-linux: 0 labels Apr 18, 2018

ikervagyok reviewed Apr 18, 2018

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xeji reviewed Apr 19, 2018

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xeji mentioned this pull request Apr 20, 2018

qemu: add separate output "ga" for qemu-ga guest agent #39212

Merged

8 tasks

matthewbauer added the 2.status: work-in-progress label Apr 21, 2018

teto force-pushed the qemu_agent branch from 56b6939 to f354b98 Compare April 26, 2018 09:33

teto changed the title ~~[WIP] qemu-guest-agent: init module~~ [RFC] qemu-guest-agent: init module Apr 26, 2018

xeji reviewed Apr 26, 2018

View reviewed changes

teto force-pushed the qemu_agent branch 2 times, most recently from 9407da6 to 514d8f2 Compare April 26, 2018 10:53

xeji reviewed Apr 26, 2018

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teto force-pushed the qemu_agent branch 2 times, most recently from 9717c8e to ca06041 Compare April 27, 2018 00:33

qemu-guest-agent: init module

ca06041

Allow out of band communication between qemu VMs and the host. Useful to retrieve IPs of VMs from the host (for instance when libvirt can't analyze DHCP requests because VMs are configured with static addresses or when there is connectivity default).

teto changed the title ~~[RFC] qemu-guest-agent: init module~~ [RDY] qemu-guest-agent: init module May 1, 2018

xeji removed the 2.status: work-in-progress label May 9, 2018

xeji changed the title ~~[RDY] qemu-guest-agent: init module~~ qemu-guest-agent: init module May 9, 2018

xeji merged commit 3d6f752 into NixOS:master May 9, 2018

teto deleted the qemu_agent branch May 10, 2018 02:20

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qemu-guest-agent: init module #39099

qemu-guest-agent: init module #39099

teto commented Apr 18, 2018 •

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qemu-guest-agent: init module #39099

qemu-guest-agent: init module #39099

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teto commented Apr 18, 2018 • edited Loading

Motivation for this change

Things done

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teto commented Apr 26, 2018

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teto commented Apr 26, 2018

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