feat: implement support for logrotate

[s3lph]

When daliserver writes a logfile, the logfile is never rotated and keeps on growing. On our system it has now reached ~6GB. This ended up filling the disk of our backup server, as we do daily backups with file-level deduplication: As the file was constantly appended to, it was never the same file, and every incremental backup contained a full copy of this file.

While trying to set up a logrotate config, I realized that daliserver did not yet contain any logic for re-opening the logfile, which is requried for logrotate to work. So this PR contains two things:

• A logrotate config for the Debian package that signals the daliserver process with SIGHUP after log rotation
• A signal handler for SIGHUP that re-opens the logfile by name.

[onitake]

Thanks for the PR!

Aside from my comments, I'd like to point out that daliserver also prints fatal and error messages to STDERR and all other messages to STDOUT.
If you're running daliserver in something that captures STDOUT/STDERR (such as systemd+journald), there's no need to enable the log file or syslog at all. I'd strongly recommend to use this instead.

[s3lph]

I'd like to point out that daliserver also prints fatal and error messages to STDERR and all other messages to STDOUT. If you're running daliserver in something that captures STDOUT/STDERR (such as systemd+journald), there's no need to enable the log file or syslog at all. I'd strongly recommend to use this instead.

Nevertheless, the default behavior of the daliserver Debian package still is to use an init script, which starts dalisever with -f /var/log/daliserver.log. As long as this is the default behavior, it should also support log rotation.

I do however also agree that systemd+journald would be the better way forward, but that's a change I'd like to see in the daliserver Debian package itself, rather than manually installing a custom systemd unit alongside the package.

[onitake]

Nevertheless, the default behavior of the daliserver Debian package still is to use an init script, which starts dalisever with -f /var/log/daliserver.log. As long as this is the default behavior, it should also support log rotation.

I do however also agree that systemd+journald would be the better way forward, but that's a change I'd like to see in the daliserver Debian package itself, rather than manually installing a custom systemd unit alongside the package.

It's high time I make that switch, then. 🙂

Sorry, dear Devuan users...

[s3lph]

Sorry, dear Devuan users...

If you would want to make Devuan users happy, you could ship both /etc/init.d/daliserver and /lib/systemd/system/daliserver.service. Systemd won't use sysv-generator to generate a unit if one with the same name already exists. So if running under systemd, the native unit is used, whereas if running under an init system that uses /etc/init.d scripts the script is used.

[onitake]

If you would want to make Devuan users happy, you could ship both /etc/init.d/daliserver and /lib/systemd/system/daliserver.service. Systemd won't use sysv-generator to generate a unit if one with the same name already exists. So if running under systemd, the native unit is used, whereas if running under an init system that uses /etc/init.d scripts the script is used.

Please take a look: #28

[onitake]

With the changed logic, part of https://github.com/onitake/daliserver/pull/27/files#diff-f7dfb3ca741707d1a361d8cdd6f75f05bc99811daac01afaa258f43d4b71e4f6R165-R174 is now redundant and can be simplified. Please remove the extra fclose(), and fold the assignment to fp_logfile into the fopen() line. There's no need for an extra temp var.

[s3lph]

Please remove the extra fclose(), and fold the assignment to fp_logfile into the fopen() line. There's no need for an extra temp var.

Done.

[onitake]

That looks good, thank you.