Setup java cache

[pjfanning]

Relates to sbt/sbt-github-actions#104

Sbt plugins are not my area of expertise. If someone could give me some pointers on how to add test coverage that would be great. https://github.com/pjfanning/sbt-typelevel/tree/setup-java-cache/github-actions currently has no src/test directory.

[armanbilge]

Hi, thanks for the PR! This is very exciting, it looks like support for sbt was added recently :)

• Add SBT in cache managers. actions/setup-java#302

Have you been using this feature in your projects? I ask because it seems there is still some WIP fixes for sbt so I am not sure how stable it is yet.

• sbt-cache: don't cache some files. actions/setup-java#332

Although, I think our custom cache step currently has the same bug 😅

If someone could give me some pointers on how to add test coverage that would be great.

Truthfully this project is shamefully lacking in tests. See #26. Because the plugin is self-hosting I try to dog-food as much as possible and I think that is sufficient in this case.

[armanbilge]

One shortcoming of this change is that caching would no longer be supported for anyone who uses a specific GraalVM version, since that doesn't use the setup-java action.

sbt-typelevel/github-actions/src/main/scala/org/typelevel/sbt/gha/WorkflowStep.scala

Lines 39 to 45 in b496145

	case jv @ JavaSpec(JavaSpec.Distribution.GraalVM(graalVersion), version) =>
	WorkflowStep.Use(
	UseRef.Public("DeLaGuardo", "setup-graalvm", "5.0"),
	name = Some(s"Setup GraalVM (${jv.render})"),
	cond = Some(s"matrix.java == '${jv.render}'"),
	params = Map("graalvm" -> graalVersion, "java" -> s"java$version")
	) :: Nil

[armanbilge]

Sorry, one more question about this: is there any way to customize the cache key? This has been on the todo because we've been having problems with reliability of caching. See:

• Smarter caching in CI #268

[pjfanning]

@armanbilge Good point about the caching when graalvm is used. The action documentation for setup-graalvm does not mention support for a cache param. So, this PR will need to be changed to re-enable the cache action when only graalvm is used in the build.

I use the setup-java caching in some of my projects but not for sbt since I use this sbt plugin. I'll have a closer look at the setup-java implementation to see if there are more issues.

Customising the cache key may be an enhancement that could be added to setup-java. I might raise an issue in that project.

[armanbilge]

Awesome. Thanks for your attention to detail, much appreciated! :)

[armanbilge]

Thank you very much for this! After doing some research I feel confident with this change.

I will fix caching for GraalVM in follow-up for #301.