[systemd-devel] systemd behavior during shutdown

[Tiwari, Hari Sahaya]

HI,
Many thanks for the reply.

I tried putting DefaultDependencies=false in both .socket & .service files.
I was able to verify that socket was still in "listening" state when my other systemd service tried to start a new connection with socket.
Also the "Suppressing connection request since unit stop is scheduled" message is no more seen.

Now I am getting below error when the new connection is requested.

Sep 19 23:31:33 jara1 systemd[1]: hacl-cfg.socket: Incoming traffic
Sep 19 23:31:33 jara1 systemd[1]: hacl-cfg at 6-127.0.0.1:5302-127.0.0.1:63714.service: Trying to enqueue job hacl-cfg at 6-127.0.0.1:5302-127.0.0.1:63714.service/start/replace
Sep 19 23:31:33 jara1 systemd[1]: Requested transaction contradicts existing jobs: Transaction is destructive.
Sep 19 23:31:33 jara1 systemd[1]: hacl-cfg.socket: One connection closed, 1 left.
Sep 19 23:31:33 jara1 systemd[1]: hacl-cfg.socket: Failed to queue service startup job (Maybe the service file is missing or not a non-template unit?): Transaction is destructive.
Sep 19 23:31:33 jara1 systemd[1]: hacl-cfg.socket: Changed listening -> failed

Do I have to set some other parameter in the systemd unit files ?

Following are the contents of systemd files,
Service File
-------------------
# cat hacl-cfg at .service
[Unit]
Description=config TCP service
Requires=hacl-cfg.socket
DefaultDependencies=false

[Service]
ExecStart=/opt/cmcluster/bin/cmclconfd -c
StandardInput=socket
KillMode=process

[Install]
WantedBy=multi-user.target

Socket File
-----------------
# cat hacl-cfg.socket
[Unit]
Description= config TCP socket
DefaultDependencies=false

[Socket]
ListenStream=5302
Accept=true
MaxConnections=900

[Install]
WantedBy=sockets.target


Service file which tries to open a new connection with hacl-cfg.socket during shutdown
--------------------------------------------------------------------------------------------------------
# cat test.service
[Unit]
Description=test Service

[Service]
ExecStart=/bin/test start
ExecStop=/bin/test stop
Type=oneshot
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target


Thanks,
Hari.

-----Original Message-----
From: Zbigniew Jędrzejewski-Szmek [mailto:zbyszek at in.waw.pl] 
Sent: Wednesday, September 19, 2018 12:11 PM
To: Tiwari, Hari Sahaya <hari-sahaya.tiwari at hpe.com>
Cc: systemd-devel at lists.freedesktop.org
Subject: Re: [systemd-devel] systemd behavior during shutdown

On Wed, Sep 19, 2018 at 05:01:33AM +0000, Tiwari, Hari Sahaya wrote:
> Hi,
> 
> I am facing one issue with systemd where systems socket is not opening a new connection during shutdown.
> I get below logs,
> 
> Sep 12 20:01:32 jara2 systemd[1]: mytestX.socket: Incoming traffic Sep 
> 12 20:01:32 jara2 systemd[1]: mytestX.socket: Suppressing connection request since unit stop is scheduled.
> 
> I have one systemd service which is trying to open a new connection during shutdown sequence but looks like systemd sockets stop accepting new connections as soon as they are marked for stop.
> I tried putting various combination of dependencies but that didn't help. Everytime getting the above message.
> 
> Is there any parameter which can be set in unit files to resolve this issue? Any pointers will be appreciated.

Hi,

yes, this is intentional. It was added to avoid the situation where services are stop and subsequently restarted during shutdown because something opens a connection, leading to loops.

If you absolutely need to open a connection to a socket activated unit, then you could try making the .socket and .service units have DefaultDependencies=false, so that they will not conflict with shutdown.target and the start jobs will not be created for them. But then you need to make sure that they actually *are* stopped at the right time, but issuing a 'systemctl stop' request for them.
This can be done, but will be messy, so I'd use a different approach if possible.

Zbyszek