[Bug 1910273] Re: Upgrade to groovy breaks DNS resolution

[Walter Schneider]

*** This bug is a duplicate of bug 1907878 ***
    https://bugs.launchpad.net/bugs/1907878

I am getting DOMAINS in /etc/resolve.conf:

DOMAINS is initialized with "DOMAINS" in `/etc/network/if-up.d/resolved`
and set in /run/systemd/resolve/netif/*

```bash
$ cat /run/systemd/resolve/netif/3
# This is private data. Do not parse.
LLMNR=yes
MDNS=no
SERVERS=DNS
DOMAINS=DOMAINS
```

systemd-resolved adds DOMAINS to domains-searchlist:
```bash
cat /etc/resolv.conf 
# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.1
nameserver 192.168.2.1
search DOMAINS lan
```

DOMAINS=$DOMAINS would have no effect and could be omitted,

As there are further errors form the if-down script (resolved: 12:
mystatedir: not found),

i've removed both `/etc/network/if-up.d/resolved` and `/etc/network/if-
down.d/resolved`.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to ifupdown in Ubuntu.
https://bugs.launchpad.net/bugs/1910273

Title:
  Upgrade to groovy breaks DNS resolution

Status in ifupdown package in Ubuntu:
  Confirmed

Bug description:
  ~# lsb_release -rd
  Description:	Ubuntu 20.10
  Release:	20.10
  ~# apt-cache policy ifupdown
  ifupdown:
    Instalēts: 0.8.35ubuntu2
    Kandidāts: 0.8.35ubuntu2
    Versiju tabula:
   *** 0.8.35ubuntu2 500
          500 http://mirrors.digitalocean.com/ubuntu groovy/universe amd64 Packages
          100 /var/lib/dpkg/status
  ~#

  Problem: Upon upgrade from Ubuntu 20.04 to Ubuntu 20.10, I expected
  name resolution upon reboot to work as usual.

  What happened:
  a) /var/log/syslog sprinkled with error messages:
  - /etc/network/if-up.d/resolved: 12: mystatedir: not found
  - /etc/network/if-up.d/resolved: 70: DNS: not found
  - /etc/network/if-up.d/resolved: 1: /run/network/ifupdown-inet-eth0: DNS=8.8.8.8 8.8.4.4: not found
  b) resolvectl dns returning no name servers

  Investigation:
  Recently changed /etc/network/if-up.d/resolved and /etc/network/if-down.d/resolved files contain programming errors. See https://git.launchpad.net/ubuntu/+source/ifupdown/commit/?id=54fec5eedfd59adaffe9021c271914578dd05d1b .

  Fix:
  $ diff /Users/pklavins/Downloads/ifupdown-0.8.35ubuntu2/debian/if-down.d/resolved if-down.d_resolved 
  12c12
  <     mystatedir statedir ifindex interface
  ---
  >     # local mystatedir statedir ifindex interface
  $ diff /Users/pklavins/Downloads/ifupdown-0.8.35ubuntu2/debian/if-up.d/resolved if-up.d_resolved 
  12c12
  <     mystatedir statedir ifindex interface
  ---
  >     # local mystatedir statedir ifindex interface
  39,40c39,40
  <     DNS=DNS
  <     DOMAINS=DOMAINS
  ---
  >     DNS=$DNS
  >     DOMAINS=$DOMAINS
  42,43c42,43
  <         DNS=DNS6
  <         DOMAINS=DOMAINS6
  ---
  >         DNS=$DNS6
  >         DOMAINS=$DOMAINS6
  47c47
  < "$DNS"="$NEW_DNS"
  ---
  > DNS="$NEW_DNS"
  51c51
  < "$DOMAINS"="$NEW_DOMAINS"
  ---
  > DOMAINS="$NEW_DOMAINS"
  70c70
  <         DNS DNS6 DOMAINS DOMAINS6 DEFAULT_ROUTE
  ---
  >         # local DNS DNS6 DOMAINS DOMAINS6 DEFAULT_ROUTE
  $

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/1910273/+subscriptions