Change default log target to STDERR

[density215]

Starting Rotonda with a configuration file that contains (some specific) errors and no logging configuration, will exit with only issuing one empty line in the CLI, even if -vvvv was issued on many systems (including mine). This depends on the standard logging facility of the system.

Setting the default log_target to STDERR instead of the system default makes sure it will always output something on the terminal if no configuration for logging was somehow passed in (or accepted by rotonda). If, on the other hand, users purposefully add log targets that don't do anything, then they are of course on their own.

Since packages for most Linux distros use systemd, and are started with an explicit log facility, I think this is the correct way to do things.

to reproduce:

rotonda -vvvv -c rotonda.example.conf

with rotonda.example.conf:

# Rotonda Example configuration file.

roto_scripts_path = "etc/examples/filters/"

http_listen = ["127.0.0.1:8080"]

[units.bgp-in]
type = "bgp-tcp-in"
listen = "0.0.0.0:11179"
my_asn = 64512
my_bgp_id = [0, 0, 0, 0]
filter_name = "my-bagger-filter"

[targets.null]
type = "null-out"
sources = ["bgp-tcp-in"]

Where "my-bagger-filter" does not exist.

[partim]

The issue is that the code in Config::finalise calls switch_logging(true), thus the logger assumes we are going into daemon mode and actives syslog as the default. If you just change that to false, all should work out as expected.