dns-resolver causing panic

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1

I’m trying to inject a message via SMTP and I get this error in the logs (journalctl):

Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.079738Z  INFO localset-0 kumod: NodeId is 2f6489ba-9d9d-47d5-83bb-8492ac3fdd93
Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.129159Z  INFO localset-0 kumo_server_common::http_server: http listener on 0.0.0.0:8000
Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.134809Z  INFO localset-0 kumod::smtp_server: smtp listener on 0.0.0.0:25
Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.134902Z  INFO localset-0 kumod::smtp_server: smtp listener on 0.0.0.0:2525
Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.134984Z  INFO localset-0 kumod::smtp_server: smtp listener on 0.0.0.0:587
Dec 26 19:30:07 send kumod[63315]: 2023-12-26T19:30:07.198429Z ERROR localset-0 insert:insert_ready: kumo_server_common::panic: panic at crates/dns-resolver/src/lib.rs:36:84 - !?
Dec 26 19:30:07 send kumod[63315]:    0: <unknown>
Dec 26 19:30:07 send kumod[63315]:    1: <unknown>
Dec 26 19:30:07 send kumod[63315]:    2: <unknown>
...
Dec 26 19:30:07 send kumod[63315]:   32: <unknown>
Dec 26 19:30:07 send kumod[63315]: thread 'localset-0' panicked at 'called `Result::unwrap()` on an `Err` value: ResolveError { kind: Io(Os { code: 2, kind: NotFound, message: "No such file or directory" }) }', crates/dns-resolver/src/lib.rs:36:84
2

Environment:

root@send:~# lsb_release -a 
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.3 LTS
Release:        22.04
Codename:       jammy
root@send:~# ls -l /etc/resolv.conf 
lrwxrwxrwx 1 root root 39 Feb 17  2023 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

(bind9 is installed)

3

I’m using kumod 2023.11.28-b5252a41

4

I think this was fixed in a dev release, can you switch to latest dev?

5

I don’t think we’ve seen this before

6

yes, I just need to uninstall the kumomta (apt remove kumomta) and install kumomta-dev following the docs, right?

7

It’ almost certainly a problem finding /etc/resolv.conf. Are you sure that the file is resolvable to the kumod process? Can you try running it under strace to see what it’s actually trying to read?

8

Ah, I’ll defer to Wez

9

Probably something like sudo -u kumod strace -e trace=file /opt/kumomta/sbin/kumod --user kumod

10

yup, that seems to be the problem:

root@send:/opt/kumomta# sudo -u kumod cat /etc/resolv.conf 
cat: /etc/resolv.conf: No such file or directory
11

hah, actually /etc/resolv.conf is a link to /run/systemd/resolve/stub-resolv.conf which doesn’t exist!

12

this is the stock ubuntu 22.04 installation with bind9 installed

13

and named is running

14

Maybe look at stuff like https://askubuntu.com/questions/134121/how-to-restore-recreate-etc-resolv-conf-files to figure out how to get a working resolv.conf back

15

yeah, fixed by running sudo systemctl enable --now systemd-resolved.service

16

Thanks!

17

As a side question - should I be running the dev version or the stable version right now? The server is going to go into production use early next week.

18

Depends on your needs: an issue with parsing FBL from Yahoo is fixed in the current dev build, as is an issue with MTA-STS. If you plan to use either of those, then you probably should run with the dev build.

In general: we try to keep the dev build in good order, but there is more of a risk of something going a bit caca vs. the stable version if you are aggressively and continually updating to the latest dev build.