Removes all our logger wrappers except the wrapper for log4j1.2. If you
depend on Elasticsearch's jar in your application you'll need to declare
log4j 1.2 and/or some bridge to your favorite logger.
We did this to simplify our builds and code. No more commons-logging like
log implementation sniffing. No more optional dependency hacks in gradle.
We might one day want to use j.u.l instead of log4j. If we do want that
we can recover its wrapper by studying this commit. We didn't go directly
to j.u.l in this commit because that is a bigger change. Our logging
configuration is based on log4j1.2 and people are used to it. So it'd
be a much more fraught breaking change to do that conversion.
This fixes the `lenient` parameter to be `missingClasses`. I will remove this boolean and we can handle them via the normal whitelist.
It also adds a check for sheisty classes (jar hell with the jdk).
This is inspired by the lucene "sheisty" classes check, but it has false positives. This check is more evil, it validates every class file against the extension classloader as a resource, to see if it exists there. If so: jar hell.
This jar hell is a problem for several reasons:
1. causes insanely-hard-to-debug problems (like bugs in forbidden-apis)
2. hides problems (like internal api access)
3. the code you think is executing, is not really executing
4. security permissions are not what you think they are
5. brings in unnecessary dependencies
6. its jar hell
The more difficult problems are stuff like jython, where these classes are simply 'uberjared' directly in, so you cant just fix them by removing a bogus dependency. And there is a legit reason for them to do that, they want to support java 1.4.
Nik Everett
Jason Tedor
Robert Muir
Ryan Ernst