I'm using GrpahHopper's self hosted routing server v0.5, running on Ubuntu 15.10.
The solution is run via a terminal with a jar file and arbitrary OSM data.
Is there a way to control the logged output of the server (e.g. to only show exceptions, bad requests, etc.)?
For that you'll have to repackage GraphHopper as there is no 'outside' configuration option provided - raise an issue if you need this.
Change the log4j.xml file under web/src/main/resources
e.g. replace the root and com.graphhopper logger via the following snippet:
<logger name="com.graphhopper" additivity="false">
<level value="warn" />
<appender-ref ref="ASYNC" />
</logger>
<root>
<priority value="warn"></priority>
<appender-ref ref="ASYNC"/>
</root>
Then repackage GH via the quickstart from source.
Update it might be possible without repackaging via
export JAVA_OPTS="-Dlog4j.debug -Dlog4j.configuration=some-log-config.xml"
using the mentioned and updated log4j.xml but I've not tested this yet. See the log4j docs