[Bug 1910273] [NEW] Upgrade to groovy breaks DNS resolution

[Pēteris Kļaviņš]

Public bug reported:

~# 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
$

** Affects: ifupdown (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1910273

Title:
  Upgrade to groovy breaks DNS resolution

Status in ifupdown package in Ubuntu:
  New

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
  $

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