Docker JRE, base image update

[srbala]

@takezoe Docker seems using older version of JRE build as base image. https://hub.docker.com/layers/gitbucket/gitbucket/4/images/sha256-909664650e090b5a44c9ac9f696e51cde34e7c79f4367402309ec2361ef20e11

Can we update to adoptopenjdk, thinking of https://hub.docker.com/r/adoptopenjdk/openjdk8-openj9, its OSS with backing of IBM.

If the team agrees, I would like to work on a pull request

[takezoe]

Do you think OpenJ9 is better than HotSpot?

[srbala]

OpenJ9 is base line for IBM JDK, derived from Oracle and IBM combo. HotSpot derivation of Oracle only. OpenJ9 is my personal choice, I have been using it more than a year (previously IBM JDK). We could put multiple docker images, OpenJ9, HotSpot, and Alpine (based images for docker smaller size).

[SIkebe]

AdoptOpenJDK9 is not LTS, so it already EOL'ed in March 2018.
https://adoptopenjdk.net/support.html

Also GitBucket is currently tested against JDK8 and 11.
(both are LTS)

[SIkebe]

Ah, I misunderstood..., its OpenJ9 and not OpenJDK9

[srbala]

Yes. Still staying with JDK8 of OpenJ9, LTS version

[takezoe]

I see. Generally speaking, HotSpot seems to be a better choise since it's used widely. However, providing multiple docker images might be a good idea if it doesn't require extra effort to maintain.

[srbala]

Docker Official jdk8 link, 1M+ downloads https://hub.docker.com/_/adoptopenjdk?tab=tags based on ubuntu base image, 205-225MB size. 1M+ downloads.

https://hub.docker.com/search?q=adoptopenjdk%2Fopenjdk8&type=image OpenJ9 jdk8, other system images debian, alpine, centos, and ubi (redhat 8), size 95-170MB. 5M+ downloads.

[takezoe]

I meant the popularity of VM itself, not docker images. However, I understood the advantage of OpenJ9 in terms of image size. If we want to provide a smaller image, OpenJ9 looks a good choice.

[aadrian]

@takezoe from the many OpenJDKs, Zulu JDKs are even better. The Docker images for them: https://github.com/zulu-openjdk/zulu-openjdk