Fixes scripts for Linux agent

[joestr]

Changes:

• Download and install latest JDK 11
• Start agent with installed JDK 11
• Fixes Agent creation fails for Linux machines #23

[chadlwilson]

Generally speaking, GoCD packages and endorses only the Adoptium / Temurin JDKs and we generally package/install the "jre" variants which are smaller. That's what we re-package with the docker images, Windows+Mac installers, Linux distros etc. There were a few peripheral places like this using the "official" OpenJDK builds. One can directly link to the relevant binary from say https://github.com/adoptium/temurin17-binaries/releases/tag/jdk-17.0.5%2B8

Need to think about this a little bit, but my gut feel is we are better to package JDK 17. That is the version that we package as a default everywhere else, and full regression currently only runs against JDK 17.

There's a bit of a challenge here insofar as

• JDK17 will only work fine with GoCD Server >= 22.1.0
• JDK11 will only work fine with GoCD Server < 21.2.0 or >= 22.1.0 (for some reason source compatibility was increased to JDK 13 changed in 21.2.0. We reverted this back to an LTS version in 22.1.0)

So there is no LTS JDK version that will work correctly with GoCD 21.2.0 or 21.3.0. That's OK, it's only two versions. For folks running older versions, I think it's fair that they will need to install their own/build their own image etc.

Which GoCD version are you folk using, I wonder?

[chadlwilson]

FWIW, there is some similar (more complex as handles multi-arch) dodgy shell scripting in https://github.com/gocd-contrib/gocd-trial-launcher/blob/9721a6b052f82b81559d7bc0a9617707499b823a/assembly/package.sh#L215-L276 that downloads temurin JREs for the purpose of the GoCD test drive at https://www.gocd.org/test-drive-gocd.html

[joestr]

I can only speak for myself, my GoCD Server runs on JDK 11 and the agent is also happy with it.

I see no issue using Adoptium JRE 17 during installation making it architecture agnostic would be really great too, but that's for another issue ticket.

[joestr]

Uses Adoptiums JDK 17 JRE now

[chadlwilson]

Thanks! Made a few tweaks in #27.

Are you able to give https://github.com/gocd/azure-elastic-agent-plugin/releases/tag/v1.2.0-53-exp a go and let me know how it goes?

Will only work on GoCD 21.4.0+ (which has the required Java 17 compatibility without various hacks).