Improve logging

[zeha]

For the following reasons, the following stuff has been suggested:

Reasons:

• test building log to syslog, where it's not useful
• systemd captures stdout + syslog

Suggestions:

• --log-stdout=on/off (better name?)
• --log-syslog=on/off

Or some combination of those (--log-dest?)

[Habbie]

It may be interesting to note that right now powerdns, internally, manages a loglevel for each and considers each line for both targets.

[Habbie]

As such, we may want to expose that explicitly - give people even more control.

[zeha]

For the future, direct journal logging support may also be nice.
Also, adding a printk-style priority to the stdout log may also be nice (for systemd users, but for those there should also be no extra date on the log line).

[zeha]

The packages in jessie have enabled native systemd unit files in --daemon=no mode, therefore we now run into the duplicate logging/timestamping problem.

[jemshad]

Option to disable syslog logging would be great.

[eht16]

I support adding an option like --log-stdout=on/off, or better --log-stderr because pdns-recursor actually logs to stderr when not running in daemon-mode.

For now, I worked around the problem by adding StandardError=null to the systemd unit file and so I don't get duplicate logs any longer.

[nhooyr]

would love to see this in the next release.

[zeha]

In the meantime, Debian has changed the systemd unit file to say Type=forking and changed --daemon=no to --daemon=yes. This has some benefits, and I'd suggest Debian users to do the same, for now. (Benefits include startup error tracking in systemd).

[Habbie]

Decision: switch to Type=forking with --daemon in our packages now. At low priority, implement --disable-syslog or similar.