I'm using openjdk:8u212-jre-slim, and it was working perfectly for me. After downloading the image again a few weeks later, however, I'm now receiving the following exception when running JavaMelody:
java.lang.NoClassDefFoundError: Could not initialize class sun.awt.X11FontManager
It appears that this was an issue with Alpine Linux in the past. I'm now experiencing it with the Debian image.
You can replicate the exception by running JavaMelody (1.77.0) inside Docker (openjdk:8u212-jre-slim).