Add systemd's unicorn service

[jstoja]

This adds a systemd unit file and uses it to start/reload the app.
It's enabled at startup with the enabled=yes.
I didn't specify the restart always because it's not handled to my knowledge now (and that it's usually a bad idea to force restarting blindly a process).

If you have any remark, please do.

Should close #7

[pushcx]

This looks like it'll handle #7, thank you. Before I merge, could you elaborate on what you mean by "restart always"?

[pushcx]

This looks like it'll handle #7, thank you. Before I merge, could you elaborate on what you mean by "restart always"?

[jstoja]

I meant using this option in the systemd’s unit file: https://www.freedesktop.org/software/systemd/man/systemd.service.html#Restart= If we want to enable this, I’d setup some monitoring to at least notify someone that it restarted (for example notify if restarted >= 3 in the last hour). What do you think about this?

…

On 29 Apr 2018, at 04:53, Peter Bhat Harkins ***@***.***> wrote: This looks like it'll handle #7, thank you. Before I merge, could you elaborate on what you mean by "restart always"? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[jstoja]

I meant using this option in the systemd’s unit file: https://www.freedesktop.org/software/systemd/man/systemd.service.html#Restart= If we want to enable this, I’d setup some monitoring to at least notify someone that it restarted (for example notify if restarted >= 3 in the last hour). What do you think about this?

…

On 29 Apr 2018, at 04:53, Peter Bhat Harkins ***@***.***> wrote: This looks like it'll handle #7, thank you. Before I merge, could you elaborate on what you mean by "restart always"? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or mute the thread.

[PeterFaiman]

Restarting services is a pretty good practice, but yes restarting forever rapidly isn’t the best idea. You can use RestartSec, RestartLimitInterval, and RestartLimitBurst to control the behavior. For example:

Restart=always
RestartSec=60
RestartLimitBurst=5
RestartLimitInterval=3600

That config will attempt to restart the process 60 seconds after it exits, but a maximum of 5 times per hour. This doesn’t affect manually stopping the process.

Those are fairly conservative settings. I use RestartSec=5 with no rate limit. But I also know what will happen if my services restart that quickly.

[PeterFaiman]

You should use $MAINPID here, which systemd automatically sets from the pidfile. It should be more reliable than finding the process by name.

[jstoja]

How about using /srv/lobste.rs/run/unicorn.pid as the PID file, since it's created by unicorn itself? I have no idea which one is the more reliable and reagarded as the best practice.

[jstoja]

That's a great idea and a very nice feedback! Thank you very much for this!
I'm changing that ASAP :)

[jstoja]

That's a great idea and a very nice feedback! Thank you very much for this!
I'm changing that ASAP :)

[jstoja]

I tested the automatic restart after a fail and it worked well with the burst limit 👍

[jstoja]

I tested the automatic restart after a fail and it worked well with the burst limit 👍

[pushcx]

This is great to have, especially with the upcoming downtime. Thanks for tackling it, @jstoja, and thank you, @PeterFaiman for collaborating to make it more robust.

[pushcx]

This is great to have, especially with the upcoming downtime. Thanks for tackling it, @jstoja, and thank you, @PeterFaiman for collaborating to make it more robust.