Drops CONFIG and FINER log levels of java.util.logging

[joshattr]

Spring boot appears to drop log statements logged with a CONFIG or FINER level using java.util.logging. I might be reading the source wrong here, and I'm unsure how to confirm this because it also doesn't let you log lower than INFO, as I understand it (I have been able to confirm this be adding log.levels.ROOT=DEBUG to my application.properties and not seeing my logs with a level of FINE/FINER/FINEST).

Here's where I think the problem is:

spring-boot/spring-boot/src/main/java/org/springframework/boot/logging/java/JavaLoggingSystem.java

Lines 51 to 57 in 0088300

	levels.put(LogLevel.TRACE, Level.FINEST);
	levels.put(LogLevel.DEBUG, Level.FINE);
	levels.put(LogLevel.INFO, Level.INFO);
	levels.put(LogLevel.WARN, Level.WARNING);
	levels.put(LogLevel.ERROR, Level.SEVERE);
	levels.put(LogLevel.FATAL, Level.SEVERE);
	levels.put(LogLevel.OFF, Level.OFF);

As an aside, wouldn't it be good if log levels were respected across logging libraries? That way you could still configure all libraries to use a certain level, but you could configure your specific library to behave the way you expect, given the logging library it's using. By defining your own levels that don't at least translate 1-1 with the library that has the most logging levels (which appears to be java.util.logging, but might be something else), you necessarily lose precision, and probably get more/less logging than you expected when using that library. This is a separate issue than the above two paragraphs.

[snicoll]

I'd rather go with the second part of the issue than the first unless I misunderstood it. The fact that you don't get CONFIG and FINERlevel with the abstraction sounds "alright" to me. The abstraction goes with a reasonable amount of logging levels that match pretty much every logging library out there (sic) but for some reason JUL decided to go crazy about this.

Having said that, if you write logging.level.com.acme.foo=CONFIG we might translate that properly for JUL but then you're using that infrastructure for configuration purposes and not for the abstraction.

[joshattr]

The config v abstraction makes sense to me. Less control over your logging library is fine, but I don't think dropping logs is. How about merging CONFIG into DEBUG and FINER into TRACE?

[snicoll]

On a more closer look (thanks @wilkinsona), CONFIG is between INFO and FINE and FINER is between FINE and FINEST. Since we map FINEST (to TRACE), I don't really see how we could "drop logs". Can you please share an example that shows that logs are dropped.

As for allowing logging library specific log level in the abstraction we decided not to do that for the reason I mentioned (using the infrastructure for configuration purposes).

[joshattr]

I'll try to spin up an example sometime in Jan when my projects calm down a bit. I might be wrong 😄

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