netplan does not allow a top-level 'nameservers' stanza

Status changed to 'Confirmed' because the bug affects multiple users.

Is there a workaround for this issue?

This is a workaround for the issue:

sudo rm -f /etc/resolv.conf
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
sudo reboot

# Known Issue
https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1624320

Please don't do that.

resolv.conf is a symlink to /run/systemd/resolve/stub-resolv.conf and should remain that way -- this makes sure any changes on the network are reflected "automatically" in the resolver's behavior, since you'd be asking systemd-resolved rather than the libc resolver, and it already knows about the contents of /run/systemd/resolve/resolv.conf.

If you must use global nameservers, you can certainly modify /etc/systemd/resolved.conf's DNS= field to add them, but be aware that "global" nameservers don't make all that much sense. Nameservers are per-interface, because they might not be reachable by all interfaces when there are multiple connected.

@cyphermox: Why should the user have to maintain nameservers in two separate places? netplan should support this and I don't think it belongs in systemd. Thanks for your help.

There seem to be a number of workarounds on the Web, and most of them revolve around modifying either the netplan config file or the systemd resolver config. None really worked for me -- usually, the resolver configuration did not survive a reboot.

I found a very unclean (but effective) workaround by restoring the old functionality of /etc/resolv.conf:

1. Remove the symlink /etc/resolv.conf
2. Create a new /etc/resolv.conf and enter your name servers and search domains.
3. Make this file immutable (chattr +i /etc/resolv.conf)
4. Wait until this bug is resolved

And yes, I am aware that this workaround is *very* ugly. This workaround is (hopefully) temporary, but it seems to me that netplan needs to be fixed first.

Mark, this bug is solely about the lack of support for top-level declarations of DNS preferences in netplan. At most, the consequence is that you must repeat yourself in the netplan config. That's suboptimal and a bug we should fix, but I don't see any reason one should ever work around it by making resolve.conf immutable.

Steve: Maybe my comment does not really belong here, I agree. I admit that I have not fully investigated the problem -- the problem in my case being that a configuration with static IP does not appear to set the DNS correctly, either via netplan (and networkd) or via systemd's resolver. A web search for this problem reveals that I am not the only one.

I also agree (and acknowledge) that my workaround is ugly.

On Tue, Sep 04, 2018 at 03:26:12PM -0000, Mark Rodgers wrote:
> Steve: Maybe my comment does not really belong here, I agree. I admit
> that I have not fully investigated the problem -- the problem in my case
> being that a configuration with static IP does not appear to set the DNS
> correctly, either via netplan (and networkd) or via systemd's resolver.
> A web search for this problem reveals that I am not the only one.

Setting DNS with a static IP is a common configuration that's well-exercised
in Ubuntu 18.04, no workarounds required. If you're having difficulty
getting the config correct, askubuntu.com is a good resource for this.

Moving it over to the netplan.io project, as nplan is deprecated.
Also, I'm marking it as a "Wishlist" item, which could be considered to be implemented as a new feature.