[systemd-devel] Discrepancy in using dhclient b/w ubuntu 20.04 and ubuntu 16.04

Tue Jun 8 12:50:58 UTC 2021

Hi Reindl,

I have attached a minimalistic repro along with the codes of all the
scripts, service files. I suppose Silvio was able to see the files. Please
refer to
https://www.mail-archive.com/systemd-devel@lists.freedesktop.org/msg46055.html
.

I have re-attached the tar again in this email.

Regards,
Aravindhan Krishnan...

On Mon, 7 Jun 2021 at 21:53, Reindl Harald <h.reindl at thelounge.net> wrote:

>
>
> Am 07.06.21 um 17:57 schrieb Aravindhan Krishnan:
> > Adding Raghav.
> >
> > And sorry the subject should have stated: Discrepancy in using dhclient
> > b/w ubuntu 20.04 and ubuntu 16.04
>
> and why didn't you fix it in your own reply?
>
> to your problem:
> you have a wild mix of docker, systemd-units and shellscripts but don't
> provide the source of the scripts nor the systemd unit
>
> overly complex for something that can be trivial as:
>
> [root at srv-rhsoft:~]$ cat /etc/systemd/system/network-wan-dhcp.service
> [Unit]
> Description=Internet DHCP-Client
>
> [Service]
> Type=forking
> ExecStart=/usr/sbin/dhclient -4 -q --no-pid --request-options
> subnet-mask,broadcast-address,routers br-wan
> PermissionsStartOnly=yes
> SuccessExitStatus=80
> Restart=always
> RestartSec=5
> ProtectSystem=strict
> ProtectHome=yes
> ReadWritePaths=-/var/lib/dhclient
> PrivateTmp=yes
> NoNewPrivileges=yes
> ProtectKernelTunables=yes
> ProtectKernelModules=yes
> ProtectControlGroups=yes
> MemoryDenyWriteExecute=yes
> CapabilityBoundingSet=CAP_NET_ADMIN CAP_NET_BIND_SERVICE
> CAP_NET_BROADCAST CAP_NET_RAW
> LockPersonality=yes
> PrivateDevices=yes
> ProtectHostname=yes
> RestrictNamespaces=yes
> RestrictRealtime=yes
> RestrictSUIDSGID=yes
> ProtectClock=true
> ProtectKernelLogs=true
> UMask=077
> SystemCallArchitectures=native
> SystemCallFilter=@system-service @network-io @privileged
> SystemCallFilter=~@aio @chown @clock @cpu-emulation @debug @keyring
> @module @mount @obsolete @raw-io @reboot @resources @swap
> InaccessiblePaths=-/boot
> InaccessiblePaths=-/efi
> InaccessiblePaths=-/root
>
> > On Mon, 7 Jun 2021 at 21:26, Aravindhan Krishnan
> > <aravindhank11 at gmail.com <mailto:aravindhank11 at gmail.com>> wrote:
> >
> >     Hi Folks,
> >
> >     I am finding anomalous behavior when I am trying to run dhclient
> >     process inside my docker container in vanilla Ubuntu 16.04 host. The
> >     service gets into "deactivating" state and is stuck forever. In the
> >     mail I have attached a minimalistic reproduction of the issue seen.
> >
> >     Working logic:
> >
> >       * There is a sample trial at .service script which invokes the
> >         `trial` binary with the option passed to the systemd service via
> >         @ option
> >       * The valid options are sleep and dhclient_<interface_name>
> >       * The binary either invokes a long-lived sleep process or dhclient
> >         process on the said interface_name based on the input
> >       * The binary then spawns `kill_trial.sh` script. The script sleeps
> >         for 20 seconds and kills the parent `trial` binary. The kill
> >         signal is SIGKILL in the trial example. In the real-world, this
> >         can be a SIGSEGV indicating a crash in the parent process.
> >       * If the trial binary was started for sleep process things work
> >         fine and service goes into "failed" state as expected
> >       * However, in case of dhclient, the service is stuck in
> >         "deactivating" state if the underlying host OS is Ubuntu 16.04.
> >         This works well if the host is running Ubuntu 20.04.
> >       * We have kept TimeoutStopSec to infinity, because in real-word
> >         deployments, the core collection post a crash takes varying time
> >         depending on the memory config on the host.
> >
> >
> >     Steps to reproduce
> >     # tar -xf minimal_repro.tar -C minimal_repro/
> >     # cd minimal_repro/
> >     # docker build -t trial .
> >     # docker rm -f trial
> >     # docker run -it -d --net=host --privileged -v
> >     /sys/fs/cgroup:/sys/fs/cgroup:ro --name trial trial
> >     # docker exec -it trial bash
> >
> >     # systemctl start trial at dhclient_eth1.service
> >
> >     # #Keep monitoring trial at dhclient_eth1.service -- issue should be
> >     seen within 20-30 seconds on Ubuntu 16.04 host
> >
> >     # systemctl status trial at dhclient_eth1.service
> >     ● trial at dhclient_eth1.service - Trial
> >           Loaded: loaded (/etc/systemd/system/trial at .service; static;
> >     vendor preset: enabled)
> >           Active: deactivating (stop-sigterm) (Result: signal) since Mon
> >     2021-06-07 13:19:12 UTC; 1min 11s ago
> >          Process: 55 ExecStartPre=/bin/bash
> >     /etc/systemd/system/trial_service_script.sh pre_start dhclient_eth1
> >     (code=exited, status=0/SUCCESS)
> >          Process: 56 ExecStart=/bin/bash
> >     /etc/systemd/system/trial_service_script.sh start dhclient_eth1
> >     (code=killed, signal=KILL)
> >         Main PID: 56 (code=killed, signal=KILL)
> >            Tasks: 0 (limit: 38590)
> >           Memory: 588.0K
> >           CGroup:
> >
>  /docker/903fca0cee1387b7c2113a36ee5efdb3a25edd1e60584fe5da5d0c5b5ffd8241/system.slice/system-trial.slice/trial at dhclient_eth1.service
> >
> >     # #NOTE: `Active: deactivating` -- in stuck state
> >     # #Running `systemctl daemon-reload` forces the service to go to
> >     failed state
> >
> >     # systemctl start trial at sleep.service
> >
> >     # #Keep monitoring trial at sleep.service -- would be killed in 20-30
> >     seconds and goes into failed state as expected
> >
> >     # # systemctl status trial at sleep.service
> >     ● trial at sleep.service - Trial
> >           Loaded: loaded (/etc/systemd/system/trial at .service; static;
> >     vendor preset: enabled)
> >           Active: failed (Result: signal) since Mon 2021-06-07 13:38:19
> >     UTC; 21s ago
> >          Process: 113 ExecStartPre=/bin/bash
> >     /etc/systemd/system/trial_service_script.sh pre_start sleep
> >     (code=exited, status=0/SUCCESS)
> >          Process: 114 ExecStart=/bin/bash
> >     /etc/systemd/system/trial_service_script.sh start sleep
> >     (code=killed, signal=KILL)
> >          Process: 129 ExecStopPost=/bin/bash
> >     /etc/systemd/system/trial_service_script.sh post_stop sleep
> >     (code=exited, status=0/SUCCESS)
> >         Main PID: 114 (code=killed, signal=KILL)
> >
> >     Please advise on what can help us in alleviating the issue.
> _______________________________________________
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> systemd-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/systemd-devel
>
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