Push Nexus logs to Datadog

SSH-ing on a server for looking at the logs is forbidden and more and more complex to achieve, if not impossible at all when the server has been drop (Docker and Kubernetes context).

=> We need the logs being pushed to Datadog.

We want all the Nexus logs in Datadog, not only the Docker output.
Actually, if all the log files are pushed, we don't need the Docker output which will be redundant as a simple tail on the nexus.log file.

The logs must be structured for being exploitable in Datadog.
This requires either writing in JSON format, either implementing custom parsers.

https://help.sonatype.com/repomanager3/configuration/support-features#SupportFeatures-LoggingandLogViewer
https://community.sonatype.com/t/how-to-override-logback-config-in-nexus-3/1151/2 
https://issues.sonatype.org/browse/NEXUS-19037
http://www.jouvinio.net/wiki/index.php/Configuration_Logs_Nexus_3

Nexus IQ seems to be already configured to use JSON format.

Do it with Nexus 3.