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@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@xxxxxxxxx <mailto:aravindhank11@xxxxxxxxx>> 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@.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@dhclient_eth1.service
# #Keep monitoring trial@dhclient_eth1.service -- issue should be
seen within 20-30 seconds on Ubuntu 16.04 host
# systemctl status trial@dhclient_eth1.service
● trial@dhclient_eth1.service - Trial
Loaded: loaded (/etc/systemd/system/trial@.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@dhclient_eth1.service
# #NOTE: `Active: deactivating` -- in stuck state
# #Running `systemctl daemon-reload` forces the service to go to
failed state
# systemctl start trial@sleep.service
# #Keep monitoring trial@sleep.service -- would be killed in 20-30
seconds and goes into failed state as expected
# # systemctl status trial@sleep.service
● trial@sleep.service - Trial
Loaded: loaded (/etc/systemd/system/trial@.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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