Recipe for migrating from JUL to slf4j? With support for `Logger.log(Level,String)` calls?

[timtebeek]

Discussed in openrewrite/rewrite#4249

^{Originally posted by woj-tek June 13, 2024}

For a long time we were using JUL (java.util.Logger, I know, bad!) and we kinda got stuck with it. However, it's getting more and more annoying to deal with it and it's high time to migrate to slf4j. I was looking for recipes to do so but found none.

I found, somewhat related, Migrate JUL to Log4j 2.x API (with the hope to use Migrate Log4j to SLF4J) but the first one didn't work because we rely heavily on Logger.log(Level,[message]) API instead of Logger.<level>(<message>) one which seems to be supported by looking at Definition and method signature.

Does anyone know any recipe for Logger.log(Level,String) calls?

[timtebeek]

hi @woj-tek; sounds like this is something that we can fairly easily implement with recipes, especially given the examples already available. Is that something you'd like to get involved with? Even just some unit tests could help speed up development.

[woj-tek]

Hi @timtebeek - indeed it seems like quite doable and good candidate for recipe. I started the discussion thread asking if there may be something already present before trying to conjure up anything myself :-)

When you say unit tests you refer to something like this: https://github.com/openrewrite/rewrite-logging-frameworks/blob/main/src/test/java/org/openrewrite/java/logging/slf4j/ChangeLogLevelTest.java which basically have source and expected result?

[timtebeek]

Yes that type of test would be perfect to capture exactly what you're after, and then know when we're done with the recipe implementation. Don't worry about getting things to work perfectly just yet; that's what draft PRs are for, and we'll whip it into shape from there.

[woj-tek]

Great, I'll try to draft something tomorrow or over the weekend - should have more time (the mere though of getting rid of JUL makes me excited) :-)

[timtebeek]

@woj-tek it occurred to me that this is a near perfect use case for our Refaster recipes

• Convert JUL Logger Level arguments to methods #156

Hope you don't mind me getting a head start to get these recipes in. :)

[timtebeek]

There are of course additional cases that we could cover, based on what you might be using there. Feel free to inform us of cases not covered yet, and we'll see about adding those too. And note that while this merely changes from JUL to JUL, you could also write recipes to go from JUL to another logging implementation for cases not covered yet.

You should be able to use our snapshot versions to try out the newly added recipes; You'll find that the JUL Logger.log(Level, ...) cases are first converted to dedicated methods, and from there to Log4J and onwards if necessary.

Edit: we seem to have an issue publishing snapshot versions; you might want to checkout this project and run ./gradlew publishToMavenLocal if you're eager to try these recipes.