Provide more details on Java 11 compatibility

[imrejonk]

Context

We are preparing our systems for the upcoming Debian 11 release. Debian 11 comes with OpenJDK 11, which is currently not fully supported by Graylog Server. The system requirements have this to say about it:

Graylog 3.x does include first compatibility with Java 11 and we welcome people that test this.

The last Debian release to include OpenJDK 8 was Debian 9, which is what we are running on our Graylog server right now. Debian 9 will receive security updates until June 30, 2022. We strongly prefer being able to update well before that date.

Expected Content

I would like to see these questions answered:

• Does Graylog 4.0 have better Java 11 compatibility than Graylog 3.3?
• What works, what doesn't?
• Would the Graylog team recommend running Graylog 4 with Java 11 in production right now? If not, what would the timeline for Java 11 support look like?

Your Environment

• Graylog Version: 4.0.8-1
• Elasticsearch Version: 6.8.16
• MongoDB Version: 4.2.14
• Operating System: Debian 9.13 (Graylog server), Debian 10.10 (syslog and web clients)
• Browser version: Firefox 78.11.0esr-1~deb10u1

[imrejonk]

I see that the new Debian 10 installation guide recommends installing openjdk-11-jre-headless. Does that mean that the Graylog developers now recommend using Java 11?