[pkg-go] Bug#985354: mtail: service unit fails to start on Bullseye

[Filippo Giunchedi]

Package: mtail
Version: 3.0.0~rc43-1+b1
Severity: important

mtail.service fails to start on Bullseye due to cgroup v2 / unified hierarchy:

$ systemctl status mtail
● mtail.service - MTail
     Loaded: loaded (/lib/systemd/system/mtail.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Tue 2021-03-16 14:32:35 CET; 1s ago
    Process: 2082384 ExecStart=/usr/bin/mtail --progs /etc/mtail --logtostderr --port 3903 --logs $LOGS (code=killed, signal=TERM)
    Process: 2082385 ExecStartPost=/bin/sh -c echo 0 > /sys/fs/cgroup/memory/system.slice/mtail.service/memory.swappiness (code=exited, status=2)
   Main PID: 2082384 (code=killed, signal=TERM)
        CPU: 49ms

Indeed memory.swappiness isn't a thing anymore:

$ find /sys/fs/cgroup/ -type f -iname 'memory.swappiness'
$


-- System Information:
Debian Release: bullseye/sid
  APT prefers testing-security
  APT policy: (500, 'testing-security'), (400, 'testing')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.10.0-3-amd64 (SMP w/4 CPU threads)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages mtail depends on:
ii  adduser              3.118
ii  daemon               0.7-1
ii  init-system-helpers  1.60
ii  libc6                2.31-9
ii  tzdata               2021a-1

mtail recommends no packages.

mtail suggests no packages.

-- no debconf information