Apt update hang in incus container terminal but run in batch from host with exec

Alessandro_Battilani · August 14, 2025, 10:29am

Hi everyone,
I’m in a strange situation.
I created a script to update my Ubuntu-based Incus containers, and it works fine, but when I try to run “apt update” in the container terminal, it hang.
In the same terminal, apt upgrade or install works fine.
This problem has been occurring for an indefinite period of time.
This is the command line that work fine:
incus exec ${1} -- sh -c "apt update 2>&1" | sed '/^$/d' | sed "s/^/$(date) - ${BGreen}${1}${Color_Off} /"
I reproducted the problem via batch from the host, using this command line
incus exec ${1} --mode=interactive -- sh -c "apt update 2>&1" | sed '/^$/d' | sed "s/^/$(date) - ${BGreen}${1}${Color_Off} /"

I tried a lot of configuration about resolv service but whitout result.

stgraber · August 14, 2025, 3:57pm

Does apt-get update have the same behavior?

apt used to complain that it wasn’t meant to be used in scripts, not sure if that changed with newer releases

Alessandro_Battilani · August 14, 2025, 6:29pm

The behavior is the same with apt-get.
in container terminal too

simos · August 15, 2025, 9:11am

Can you create a simplified reproducible and post below? Add the full instructions so that anyone can reproduce. For example, try to remove the multiple pipes in the commands so that you reach the simplest command that does hang.

Alessandro_Battilani · August 15, 2025, 7:15pm

Sorry for the long reply, but I’ll try to give you some additional information.

Theese are the semplified command line from host
incus exec mysql -- sh -c "apt update" > work fine

incus exec mysql --mode=interactive -- sh -c "apt update" > hangs

This is the script that I used for test the different behavior:

#!/bin/bash
BRed=$'\033[1;31m'   # Red
BGreen=$'\033[1;32m' # Green
Color_Off=$'\033[0m' # Text Reset
TMSTMP=$(date +'%Y%m%d%H%M%S')
function update_container() {
    #incus exec ${1} --mode=interactive -- sh -c "apt-get update 2>&1" | sed '/^$/d' | sed "s/^/$(date) - ${BGreen}${1}${Color_Off} /" 
    incus exec ${1} -- sh -c "apt update 2>&1" | sed '/^$/d' | sed "s/^/$(date) - ${BGreen}${1}${Color_Off} /"
}
echo $(date) "- ${BGreen}Start updating incus container...${Color_Off}"
    update_container mysql
echo $(date) "- ${BGreen}Updating incus container ended.${Color_Off}"

and below the output of the script in the two cases

alex@alex-XPS-15-9570:~/scripts$ ./update-incus-container-test.sh 
ven 15 ago 2025, 20:41:49, CEST - Start updating incus container...
ven 15 ago 2025, 20:41:49, CEST - mysql ^Cven 15 ago 2025, 20:45:58, CEST - Updating incus container ended.
alex@alex-XPS-15-9570:~/scripts$ ./update-incus-container-test.sh 
ven 15 ago 2025, 20:46:45, CEST - Start updating incus container...
ven 15 ago 2025, 20:46:45, CEST - mysql WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
ven 15 ago 2025, 20:46:45, CEST - mysql Hit:1 http://archive.ubuntu.com/ubuntu jammy InRelease
ven 15 ago 2025, 20:46:45, CEST - mysql Hit:2 http://archive.ubuntu.com/ubuntu jammy-updates InRelease
ven 15 ago 2025, 20:46:45, CEST - mysql Hit:3 http://archive.ubuntu.com/ubuntu jammy-backports InRelease
ven 15 ago 2025, 20:46:45, CEST - mysql Hit:4 http://security.ubuntu.com/ubuntu jammy-security InRelease
ven 15 ago 2025, 20:46:45, CEST - mysql Reading package lists...
ven 15 ago 2025, 20:46:45, CEST - mysql Building dependency tree...
ven 15 ago 2025, 20:46:45, CEST - mysql Reading state information...
ven 15 ago 2025, 20:46:45, CEST - mysql 2 packages can be upgraded. Run 'apt list --upgradable' to see them.
ven 15 ago 2025, 20:46:48, CEST - Updating incus container ended.

In the case that hangs, in the incus-ui operations panel, there’s this notification:

command: ["sh","-c","apt-get update 2>&1"]environment: {"HOME":"/root","LANG":"C.UTF-8","PATH":"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin","TERM":"xterm-256color","TZ":"Europe/Rome","USER":"root"}fds: {"0":"4d43b437d5c026c093f00b7e6e2fc5e7e4ad7bdb4e3b46b09043abe5278c9e83","control":"c9534f03029b967ef9ceb08cf6e45d1fef7e9b8c91b49553759eec5cf8ad24af"}interactive: true

My incus configuration is the default and mysql container configuration is:
alex@alex-XPS-15-9570:~/scripts$ incus info mysql
Name: mysql
Description: mysql
Status: RUNNING
Type: container
Architettura: x86_64
PID: 6977
Created: 2023/12/17 16:24 CET
Last Used: 2025/08/15 20:33 CEST
Started: 2025/08/15 20:33 CEST

Resources:
Processes: 98
Utilizzo disco:
root: 8.44GiB
Utilizzo CPU:
Utilizzo CPU (in secondi): 42
Memory usage:
Memory (current): 639.86MiB
Network usage:
eth0:
Type: broadcast
State: UP
Host interface: vethd3405a29
MAC address: 00:16:3e:be:6a:29
MTU: 1500
Bytes ricevuti: 9.56MB
Byte inviati: 429.36kB
Packets received: 6566
Packets sent: 5334
IP addresses:
inet: 10.211.114.173/24 (global)
inet6: fe80::216:3eff:febe:6a29/64 (link)
lo:
Type: loopback
State: UP
MTU: 65536
Bytes ricevuti: 15.61kB
Byte inviati: 15.61kB
Packets received: 126
Packets sent: 126
IP addresses:
inet: 127.0.0.1/8 (local)
inet6: ::1/128 (local)