Replace SysV init script by a Systemd service file.

[JoseGoncalves]

Now that KMS has dropped support for Ubuntu Trusty, I think we should drop also the SysV init script and replace it by a Systemd service file.

There are some things that the current SysV init script handles that the Systemd service proposed in this PR does not (and, I think, it should not):

• Create and initialize ownership + perms for logs directory
• Set the Kernel core dump pattern if given by the user in the configuration file

A thing that I did not find a way to do is to dynamically set the per-process max open file descriptors to half of system-wide max. I've set a conservative default of 100000 files in the service file, that can be changed by users via command systemctl edit kurento-media-server.

[jenkinskurento]

Hi there, thanks for your Pull Request!

A Kurento member needs to verify that this patch is reasonable to test. In case it is, they should write a comment with the phrase test this please. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by Kurento members will still work. Regular contributors can be whitelisted to skip this step.

[paulmenzel]

Thank you for doing this. It looks good to me.

Personally, I let the “upstream” (outside the Debian directory) provide the systemd service unit, and let CMake install it.

[dpocock]

Feel free to compare this with the way we do it in reSIProcate. I take a lot of care to synchronize this between the upstream project, the Debian packages and the Fedora / EPEL RPM packages.

Having a systemd unit file is a good idea

Some people still need the init script for other operating systems (Devuan, BSD) and so I don't think it is a good idea to remove it. They can coexist.

[JoseGoncalves]

I'm not using Kurento anymore, so I leave this up to you.

While the SysV init scripts can coexist with Systemd service files I don't think it's a good idea to maintain both in a package, because of the extra burden of maintaining two different environment configs. I think that if you are targeting Debian/Ubuntu packages, you should stick with Systemd and let someone using non-Systemd distros to package Kurento with an init script.