Switch to official Tomcat 9 - jre 11 base image

[ahennr]

In this PR a change of the base image to the official Tomcat 9 (tomcat:9.0.85-jre11-temurin-jammy) image is suggested (internally based on ubuntu 22.04). In particular, I see the following advantages of this change:

• By using this image, Java and Tomcat do not have to be installed manually and they are pre-configured in a consistent way
• Since the Tomcat image is regularly updated on the operating system level as well as on the Tomcat side, this can be used to continuously update the built images and release them with the same tag but different digest when updating the base image, if the GeoServer version remains the same.
  • See also the discussion in https://osgeo-org.atlassian.net/browse/GEOS-11231
• The resulting GeoServer image is about 38% smaller than the one currently provided

[buehner]

Thank you. I like this change and will take some time soon to test this extensively to ensure that all available features are still working with such a "basic" change.

[buehner]

We could think about introducing build args like

ARG TOMCAT_VERSION=9.0.85
ARG JAVA_VERSION=11

FROM tomcat:${TOMCAT_VERSION}-jre{JAVA_VERSION}-temurin-jammy

This would give the build more flexibility.

We were previously using the jdk instead of jre. I don't know if there was a reason for this? Maybe @jodygarnett knows?

[jodygarnett]

I do not know, GeoServer is supposed to only require JRE.

[aaime]

Agreed. But it might be tricky to get the JRE going, as it often requires less dependencies, which end up tripping either the startup, the map rendering, or specifically, the point rendering (fontconfig/harfbuzz not being installed or not completely working). Try it out with "topp:states", if that works, it should be fine.

[ahennr]

The idea behind using the JRE image was that this would result in a smaller GeoServer image. I didn't realize that this could lead to side-effects in rendering for example. Thanks @aaime for this hint!

In 2de74a9 I switched back to JDK in order to be consistent with the previous version and to avoid the difficulties of using the JRE (see above comment). Furthermore, due to the changes in #39, the catalina.jar has to be packed/unpacked using jar to exchange the version info which is not available in the JRE image.

[buehner]

Would be great if you could resolve the conflicts @ahennr 🙏

[ahennr]

Would be great if you could resolve the conflicts @ahennr 🙏

🏁