[JAVA] Move to JDK21

[andrijapanicsb]

The required feature described as a wish

CloudStack now runs on JDK 17, strict requirement.

JDK 17 is EoL this September (Oracle) and in less than a 1y with other "providers":

Vendor Support End Dates for OpenJDK 17

• Oracle JDK 17: Premier Support ends on September 30, 2026 (with Extended Support running through September 30, 2029).
• Microsoft Build of OpenJDK 17: Supported until September 30, 2027.
• Eclipse Temurin (Adoptium): Supported until at least October 31, 2027.
• Red Hat build of OpenJDK 17: Supported until December 31, 2027.

JDK25 is too cutting-edge and has a narrow ecosystem, so the recommended LTS to switch to is JDK 21.

[andrijapanicsb]

Newer distros don't even ship Java 17 any more and custom repos are needed. Time to upgrade.

[weizhouapache]

@andrijapanicsb
Java 21 has been already supported since @vishesh92 's PR #11546

I also ran the smoke tests on Debian 13 against 4.23.0.0-RC3, and everything worked without any issues.

openjdk-17 is not available in Debian 13.

cc @harikrishna-patnala

[weizhouapache]

just checked a OL10 host, it also use java 21

[andrijapanicsb]

Thx @weizhouapache great - but did I read correctly this is for EL10 only? Does it support other OS-es (Debian 13,12) any other ?

[andrijapanicsb]

Now I see tests passing on Suse 15, EL10 and you also mention Debian 13 - cool. Still question - do older OS-es (assuming manual installation might be required will also run Java21)?

[weizhouapache]

Now I see tests passing on Suse 15, EL10 and you also mention Debian 13 - cool. Still question - do older OS-es (assuming manual installation might be required will also run Java21)?

IMO, users should be able to choose either Java 17 or Java 21. Both should work, including on older OS versions, as long as the chosen Java version is supported on that OS.