[systemd-devel] Per-connection socket activation not always running service

Sat Sep 12 23:13:21 PDT 2015

27.08.2015 04:52, John Pitney пишет:
> To check my understanding of how per-connection socket activation
> works, I've tried to make a very simple socket-activated service which
> runs any input through md5sum, writes md5sum's output to the journal,
> and then sleeps for one second.  What I have works, but only
> sometimes.  Frequently, no md5sum output appears in the journal, and
> eventually the service goes into a failed state, but I don't see why.
>
> Here are my unit files:
>
> # cat /etc/systemd/system/md5.socket
> [Unit]
> Description=md5sum socket
>
> [Socket]
> ListenStream=8075
> Accept=yes
>
> [Install]
> WantedBy=sockets.target
> # cat /etc/systemd/system/md5 at .service
> [Unit]
> Description=md5sum service
>
> [Service]
> ExecStart=/usr/bin/sh -c '/usr/bin/md5sum ; sleep 1'
> StandardInput=socket
> StandardOutput=journal
>
> Here, I see what to look for in the journal, possibly in some other order.
>
> # for i in $(seq 1 8) ; do echo $i|md5sum ; done
> b026324c6904b2a9cb4b88d6d61c81d1  -
> 26ab0db90d72e28ad0ba1e22ee510510  -
> 6d7fce9fee471194aa8b5b6e47267f03  -
> 48a24b70a0b376535542b996af517398  -
> 1dcca23355272056f04fe8bf20edfce0  -
> 9ae0ea9e3c9c6e1b9b6252c8395efdc1  -
> 84bc3da1b3e33a18e8d5e1bdd7a18d7a  -
> c30f7472766d25af1dc80b3ffc9a58c7  -
>
> Here, I send the same eight strings to the service.
>
> # for i in $(seq 1 8) ; do echo $i|nc -c localhost 8075 & done
>
> Only one of these (number 5) shows up with output in the journal.
>
> # journalctl -b -u "md5*" --since "20:20:00"
> -- Logs begin at Sat 2014-11-29 13:38:04 CST, end at Wed 2015-08-26
> 20:33:19 CDT. --
> Aug 26 20:24:55 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55635).
> Aug 26 20:24:55 archie-01 sh[24705]: 1dcca23355272056f04fe8bf20edfce0  -
>
> If I try the same for loop a few more times, I got one round of all
> eight md5sums appearing in the journal, but in the next round, I get a
> few md5sums before I start getting errors.
>
> # journalctl -b -u "md5*" --since "20:30:00" --no-pager
> -- Logs begin at Sat 2014-11-29 13:38:04 CST, end at Wed 2015-08-26
> 20:36:16 CDT. --
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55643).
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55644).
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55645).
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55646).
> Aug 26 20:35:12 archie-01 sh[24752]: 26ab0db90d72e28ad0ba1e22ee510510  -
> Aug 26 20:35:12 archie-01 sh[24750]: b026324c6904b2a9cb4b88d6d61c81d1  -
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55647).
> Aug 26 20:35:12 archie-01 sh[24756]: 6d7fce9fee471194aa8b5b6e47267f03  -
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55648).
> Aug 26 20:35:12 archie-01 sh[24760]: 1dcca23355272056f04fe8bf20edfce0  -
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55649).
> Aug 26 20:35:12 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55650).
> Aug 26 20:35:12 archie-01 sh[24754]: c30f7472766d25af1dc80b3ffc9a58c7  -
> Aug 26 20:35:12 archie-01 sh[24763]: 48a24b70a0b376535542b996af517398  -
> Aug 26 20:35:12 archie-01 sh[24766]: 9ae0ea9e3c9c6e1b9b6252c8395efdc1  -
> Aug 26 20:35:12 archie-01 sh[24768]: 84bc3da1b3e33a18e8d5e1bdd7a18d7a  -
> Aug 26 20:36:16 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55651).
> Aug 26 20:36:16 archie-01 sh[24813]: 6d7fce9fee471194aa8b5b6e47267f03  -
> Aug 26 20:36:16 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55652).
> Aug 26 20:36:16 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55653).
> Aug 26 20:36:16 archie-01 sh[24816]: 1dcca23355272056f04fe8bf20edfce0  -
> Aug 26 20:36:16 archie-01 sh[24818]: 48a24b70a0b376535542b996af517398  -
> Aug 26 20:36:16 archie-01 systemd[1]: Started md5sum service (127.0.0.1:55657).
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 14-127.0.0.1:8075-127.0.0.1:55656.service: Failed to run 'start'
> task: Transport endpoint is not connected
> Aug 26 20:36:16 archie-01 systemd[1]: Failed to start md5sum service
> (127.0.0.1:55656).
> Aug 26 20:36:16 archie-01 sh[24821]: 84bc3da1b3e33a18e8d5e1bdd7a18d7a  -
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 14-127.0.0.1:8075-127.0.0.1:55656.service: Unit entered failed
> state.
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 14-127.0.0.1:8075-127.0.0.1:55656.service: Failed with result
> 'resources'.
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 13-127.0.0.1:8075-127.0.0.1:55655.service: Failed to run 'start'
> task: Transport endpoint is not connected
> Aug 26 20:36:16 archie-01 systemd[1]: Failed to start md5sum service
> (127.0.0.1:55655).
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 13-127.0.0.1:8075-127.0.0.1:55655.service: Unit entered failed
> state.
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 13-127.0.0.1:8075-127.0.0.1:55655.service: Failed with result
> 'resources'.
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 12-127.0.0.1:8075-127.0.0.1:55654.service: Failed to run 'start'
> task: Transport endpoint is not connected
> Aug 26 20:36:16 archie-01 systemd[1]: Failed to start md5sum service
> (127.0.0.1:55654).
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 12-127.0.0.1:8075-127.0.0.1:55654.service: Unit entered failed
> state.
> Aug 26 20:36:16 archie-01 systemd[1]:
> md5 at 12-127.0.0.1:8075-127.0.0.1:55654.service: Failed with result
> 'resources'.
>

I cannot really reproduce them using openSUSE Tumbleweed with systemd 
219 (patched).

> What do these error messages mean?
>

Kernel returned ENOTCONN when systemd tried to do something with socket 
(may be dup it). Actually I would not be surprised if nc already closed 
socket from its side at this point. It could be kernel issue.

> These unit files are probably not correct somehow---what should I
> change to make this work, even when many connections are made
> concurrently?
>
> Thanks,
> John
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