Recommend changing the default `openjdk:8` Docker image

[dwickern]

sbt-native-packager/src/main/scala/com/typesafe/sbt/packager/docker/DockerPlugin.scala

Line 84 in eecea01

dockerBaseImage := "openjdk:8",

Users should change openjdk to something else. https://hub.docker.com/_/openjdk has some alternatives.

We could remove the default value (breaking change) or add some validation to warn the user

[muuki88]

Fair point. Is there a good other default? Would the eclipse-temurin image be a viable solution as this is the only one backed by an open source org?

[mzuehlke]

eclipse-temurin:8 seems likely to be the most minimal change.

[muuki88]

Let's go for eclipse-termurin:8 then. I mean... Java8 is EOL anyways, right?

[mzuehlke]

Let's go for eclipse-termurin:8 then. I mean... Java8 is EOL anyways, right?

Oracle will support it till December 2030 🙃

[dwickern]

I have a hard time choosing a default... I feel like the user needs to choose which distribution and especially which JVM version

If we simply removed the default value, it would break users on openjdk:8 which seems like a good thing. Would it break any other use-cases?

[SethTisue]

I would suggest defaulting to at least 17. You could make a good argument for defaulting to latest-LTS (currently 21, soon to be 25).

[muuki88]

I tend to agree with @dwickern . For the "please upgrade" reason, but also not to endorse a certain vendor.

Still, I hate it when a build tool requires a lot of configuration and doesn't just work with sensible defaults.
Which is why @SethTisue suggestion is probably the most reasonable one and default to the next LTS version ( 25 ).

[mihe-inf]

If we simply removed the default value, it would break users on openjdk:8 which seems like a good thing. Would it break any other use-cases?

This is no longer an issue, because the openjdk:8 tag was just removed from the registry today, so having this value at all is now breaking anyway, see docker-library/openjdk#551