Experimental Physics and
Industrial Control System

Andrew Johnson <[email protected]> · Mon, 27 Jun 2016 13:46:42 -0500

Hi Martin,

On 06/27/2016 12:48 PM, Konrad, Martin wrote:
>> Has anybody produced a systemd unit file for running the caRepeater?
> Nope. But something along the following lines should get you started:
>
> [Unit]
> Description=EPICS CA Repeater
> Requires=network.target
> After=network.target
> 
> [Service]
> ExecStart=/usr/bin/caRepeater
> Restart=always
> User=carepeater
> 
> [Install]
> WantedBy=multi-user.target

Thanks. Doesn't the "user=carepeater" parameter mean that there must be
a username called carepeater that is used just to run the repeater? I
would probably default to something like daemon instead.

>> It should be possible to extend the CA Repeater client with an option
>> to accept an open socket
> Are you suggesting to replace the caRepeater autostart functionality by
> systemd's socket activation in the long run?

Not replacing it (we will always need it to autostart for when an IOC is
running on an embedded system say), but adding the ability to use socket
activation when desired would make sense.

Its better if the repeater gets started automatically by the system so
the process doesn't run as a regular user or look like it's some random
CA client that hasn't been properly killed, thus for a long time Base
has built a sysv-init script S99caRepeater on Linux and Solaris. The
systemd unit file would provide an alternative to that; adding socket
activation seems like a sensible minor enhancement to avoid starting the
repeater unnecessarily.

Having a repeater that is started by socket activation automatically
exit when its last client disconnects would be an obviously-related
enhancement, but might take a bit more work.

- Andrew

-- 
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System