This commit modifies the build to require JDK 9 for
compilation. Henceforth, we will compile with a JDK 9 compiler targeting
JDK 8 as the class file format. Optionally, RUNTIME_JAVA_HOME can be set
as the runtime JDK used for running tests. To enable this change, we
separate the meaning of the compiler Java home versus the runtime Java
home. If the runtime Java home is not set (via RUNTIME_JAVA_HOME) then
we fallback to using JAVA_HOME as the runtime Java home. This enables:
- developers only have to set one Java home (JAVA_HOME)
- developers can set an optional Java home (RUNTIME_JAVA_HOME) to test
on the minimum supported runtime
- we can test compiling with JDK 9 running on JDK 8 and compiling with
JDK 9 running on JDK 9 in CI
JDK9 removed pathname canonicalization when constructing FilePermission objects, which breaks some of the FilePermissions added by
Elasticsearch. This commit adds the system property jdk.io.permissionsUseCanonicalPath which makes JDK9 behave like JDK8 w.r.t. FilePermissions (see
https://github.com/elastic/elasticsearch/issues/21534).
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.
Transitive dependencies can be confusing and hard to deal with when
conflicts arise between them. This change removes transitive
dependencies from elasticsearch, and forces any dependency conflicts to
be resolved manually, instead of automatically by gradle.
closes#14627
Jason Tedor
Tanguy Leroux
Yannick Welsch
Simon Willnauer
Nik Everett
Robert Muir
Ryan Ernst