Enable networkd by default #202488

lheckemann · 2022-11-23T09:37:05Z

Description of changes

Enables networkd by default and adjusts docs and tests accordingly.

Things done

This results in a more sensible behaviour for common setups, such as workstations with both WiFi and Ethernet interfaces where only one needs to be connected for online status to be reached -- which is exactly the scenario useDHCP is for. This also allows simplifying the config generated by the installer: we don't need per-interface declarations at all anymore.

The example is outdated, as NixOS's networking options have supported static IPv6 configuration for a long time now. With networkd being enabled by default, networking.localCommands loses further relevance and should only be used in extremely niche use cases -- and certainly not encouraged for use cases as common as setting IPv6 addresses.

Since networkd is now enabled by default, we no longer need to enable it explicitly.

SuperSandro2000 · 2022-11-23T15:17:07Z

nixos/modules/tasks/network-interfaces-systemd.nix

@@ -74,6 +74,7 @@ in
        enable = true;
      }
      (mkIf cfg.useDHCP {
+        wait-online.anyInterface = lib.mkDefault true;


I frequently see problems with wait-online timing out already because it tracks to many interfaces. Wouldn't this make this worse?

No, this does the exact opposite. Its just waits for any of the interfaces to come online.

danielbarter · 2023-03-16T02:32:09Z

super stoked for this!

I have been using the networkd backend for a while now and it is rock solid. Might be worth adding some docs about how networking.<interface> and systemd.network.networks.<interface> are related. I found this confusing at first. I would be happy to write something, unless there is any objection.

lheckemann · 2023-03-17T10:53:47Z

@danielbarter yes, that would be great! If you want to pair at some point to get this moving again let me know, I'm @linus:schreibt.jetzt (you can find me in most of the big Nix-related channels) on Matrix :)

danielbarter · 2023-03-20T05:03:53Z

👍. Should have some time next weekend.

nixos-discourse · 2023-03-23T05:17:48Z

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/california-bay-area-meetup-nix-20th/26553/3

onny · 2023-06-18T10:45:52Z

Really looking forward to have this in 23.11. Had much better experience with networking.useNetworkd = true; regarding IPv6 support

mweinelt · 2023-09-17T20:18:32Z

The tests for kea and networkd-prefix-delegation rely on networkd only, so I expect them to be fine.

mkg20001 · 2023-10-04T00:36:52Z

nixos/tests/cjdns.nix

@@ -7,6 +7,9 @@ let
    { ... }:
    { services.cjdns.enable = true;

+      # Occupies port 53 otherwise
+      services.resolved.enable = false;


CJDNS is actually unrelated to DNS (at least in a direct sense), this shouldn't be necesarry

Majiir · 2023-10-07T05:17:07Z

I'm also excited for networkd, but to temper the enthusiasm above: I have been trying to switch my systems to networkd for about a week now and haven't yet succeeded. I will keep opening PRs and issues as I discover details, but to briefly list what I've been running into:

If I switch or test from a scripted configuration to one with useNetworkd, I lose all interface connectivity on the target host (for some hosts with non-trivial network configs). This can happen even when a clean boot into the new config works. I haven't yet pinned down the root cause, but I found that some permutation of enabling resolved or systemd.network.enable (without useNetworkd) triggered the issue. It might also have something to do with dhcpcd. Why is this an issue? Because it makes switching more difficult to pull off on systems where lots of rebooting creates too much downtime (like a router or server).
I found some of my networks were configured nonsensically with useNetworkd. See nixos/network-interfaces-systemd: don't set network-level domains #258677 and nixos/network-interfaces-systemd: support and require defaultGateway.interface #258695 for fixes.
I ran into (still undiagnosed) issues with NixOS container connectivity when enabling useNetworkd.
The default services enabled with useNetworkd can clash with an existing configuration in unexpected ways. For example, enabling useNetworkd on my router broke DNS on my network because the router runs dnsmasq, which conflicted with the ports bound by the now-enabled-by-default resolved.

Some of these are issues we can fix in nixpkgs, while others are footguns that users should be made aware of prominently in the release notes.

Since there could be myriad problems for existing users, would it make sense to start by enabling useNetworkd for new installations (through a stateVersion check and/or default config) and see what happens with a broader audience? I suspect most current useNetworkd users are competent early adopters.

lheckemann · 2023-10-07T15:23:12Z

switching doesn't work: this is a known issue and I don't think it's something we should invest much effort into improving (though it might be worth detecting this and cancelling a switch). Systems should be rebooted on a regular basis to ensure they're running recent kernels anyway, and upgrading to a new release is generally expected to require a reboot.

silly configuration: some good catches there, thanks!

containers: maybe @Ma27 knows something relevant?

services on port 53: these problems are exposed by many of the tests, which is why I put a big checklist in the description and some discussion on here about what the best way to deal with that is.

Majiir · 2023-10-07T15:32:10Z

switching doesn't work: this is a known issue and I don't think it's something we should invest much effort into improving (though it might be worth detecting this and cancelling a switch).

Yes, detecting and cancelling would help if there aren't plans to support it. It's not only an issue for release (where as you say, a reboot is expected) but also in case users want to make the switch sometime before or after the release. The issue with a required reboot isn't one reboot, but the potentially many reboots and loss-of-connectivity events that come with troubleshooting the switch to networkd.

services on port 53: these problems are exposed by many of the tests, which is why I put a big checklist in the description and some discussion on here about what the best way to deal with that is.

👍 I don't see a dnsmasq test there but I can find or make one. It seems adding --bind-interfaces to dnsmasq options is the generally accepted way to make it play nicely with resolved (and I found this to work).

Majiir · 2023-10-07T20:11:07Z

More config generation fixes:

Majiir · 2023-10-07T22:24:41Z

Failing test for dnsmasq+resolved: #259644

Majiir · 2023-10-08T01:34:10Z

Ohh, here's a fun one! I switched a machine to networkd and its DHCP-assigned IPv4 address changed even though this machine's MAC address has a static address reservation configured on the DHCP server (Kea). This happened because the DHCP Client ID changed when switching to networkd. I don't think we can do anything to fix this, but we should mention it in the upgrade instructions when networkd becomes the default.

[EDIT to avoid notification spam] I think my container issues are caused by enabling systemd-resolved on the host. These are declarative containers with the default networking.useHostResolvConf value (true). Whereas resolv.conf previously pointed to nameservers on the network that the container could reach, it now points at 127.0.0.53, but resolved is not running in the container, it's running on the host.

Ma27 · 2023-10-09T17:12:15Z

re containers: if it's about DNS, you'll most likely need sth. like networking.useHostResolvConf = !hostConfig.networking.useNetworkd;.

"issues with NixOS container connectivity" is rather vague, so that's just a wild guess.

Even the existing container subsystem works surprisingly well with networkd I discovered over the last months.

EDIT: OK, seems as if the issue was found already. The message appeared right after I submitted, thanks GitHub 🙃

Ma27 · 2023-10-23T09:26:37Z

Ah I thought I had sent this comment last week, but apparently I didn't. Anyways, here we go:

Fix tests known to be broken by this PR

Haven't looked through all, but e.g. openssh is only broken because of the underscores in the hostnames. I totally forgot about this, but given that resolved prohibits this, we should drop it entirely from the testing framework.

lheckemann · 2023-11-02T07:59:08Z

Superseded by #264967

NixOS/nixpkgs#202488

lheckemann added 5 commits November 22, 2022 15:07

nixos/networkd: enable by default

6d40ec5

nixos/manual: add networkd default to release notes

41976de

nixos/tests: remove explicit useNetworkd

92da081

Since networkd is now enabled by default, we no longer need to enable it explicitly.

lheckemann requested review from fpletz, Ma27 and grahamc November 23, 2022 09:37

github-actions bot added 6.topic: nixos 8.has: changelog 8.has: documentation 8.has: module (update) labels Nov 23, 2022

ofborg bot added 10.rebuild-darwin: 0 10.rebuild-linux: 1-10 labels Nov 23, 2022

SuperSandro2000 reviewed Nov 23, 2022

View reviewed changes

fpletz approved these changes Nov 24, 2022

View reviewed changes

lheckemann added 3 commits November 28, 2022 18:38

nixos/tests/powerdns: fix for networkd?

36c52e1

nixos/cloud-init: don't disable networkd

71a2e74

containers: only use host resolv.conf if networkd is disabled

f9dfb49

lheckemann force-pushed the networkd-default branch from db893db to f9dfb49 Compare November 28, 2022 17:46

lheckemann added 3 commits November 28, 2022 19:15

nixos/tests/ncdns: disable resolved

9d3e209

fixup release-notes: link to existing option

e53a3de

fix a bunch of resolved-related test failures

8593cc0

xaverdh mentioned this pull request Jan 2, 2023

Switch to systemd-networkd #10001

Open

infinisil added the significant Novel ideas, large API changes, notable refactorings, issues with RFC potential, etc. label Apr 19, 2023

mkg20001 reviewed Oct 4, 2023

View reviewed changes

Majiir mentioned this pull request Oct 7, 2023

nixos/tests: add failing test for dnsmasq+resolved #259644

Closed

12 tasks

Ma27 mentioned this pull request Oct 24, 2023

nixos/tests/openssh: use dashes for hostnames #263131

Merged

13 tasks

lheckemann mentioned this pull request Nov 2, 2023

Enable networkd by default #264967

Open

40 tasks

lheckemann closed this Nov 2, 2023

caspervk pushed a commit to caspervk/nixos that referenced this pull request Jun 11, 2024

systemd-networkd

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NixOS/nixpkgs#202488

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Enable networkd by default #202488

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lheckemann commented Nov 23, 2022 •

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Enable networkd by default #202488

Enable networkd by default #202488

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lheckemann commented Nov 23, 2022 • edited by Ma27 Loading

Description of changes

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