This PR represents the initial phase of Modularizing Elasticsearch (with
Java Modules).
This initial phase modularizes the core of the Elasticsearch server
with Java Modules, which is then used to load and configure extension
components atop the server. Only a subset of extension components are
modularized at this stage (other components come in a later phase).
Components are loaded dynamically at runtime with custom class loaders
(same as is currently done). Components with a module-info.class are
defined to a module layer.
This architecture is somewhat akin to the Modular JDK, where
applications run on the classpath. In the analogy, the Elasticsearch
server modules are the platform (thus are always resolved and present),
while components without a module-info.class are non-modular code
running atop the Elasticsearch server modules. The extension components
cannot access types from non-exported packages of the server modules, in
the same way that classpath applications cannot access types from
non-exported packages of modules from the JDK. Broadly, the core
Elasticseach java modules simply "wrap" the existing packages and export
them. There are opportunites to export less, which is best done in more
narrowly focused follow-up PRs.
The Elasticsearch distribution startup scripts are updated to put jars
on the module path (the class path is empty), so the distribution will
run the core of the server as java modules. A number of key components
have been retrofitted with module-info.java's too, and the remaining
components can follow later. Unit and functional tests run as
non-modular (since they commonly require package-private access), while
higher-level integration tests, that run the distribution, run as
modular.
Co-authored-by: Chris Hegarty <christopher.hegarty@elastic.co>
Co-authored-by: Ryan Ernst <ryan@iernst.net>
Co-authored-by: Rene Groeschke <rene@elastic.co>
The plugin classloader exists in its own jar file for legacy reasons,
and while it should go away in the future, it currently duplicates the
package name of the rest of the plugin classes. This commit moves the
classloader into its own unique package.
relates #73784
As per the new licensing change for Elasticsearch and Kibana this commit
moves existing Apache 2.0 licensed source code to the new dual license
SSPL+Elastic license 2.0. In addition, existing x-pack code now uses
the new version 2.0 of the Elastic license. Full changes include:
- Updating LICENSE and NOTICE files throughout the code base, as well
as those packaged in our published artifacts
- Update IDE integration to now use the new license header on newly
created source files
- Remove references to the "OSS" distribution from our documentation
- Update build time verification checks to no longer allow Apache 2.0
license header in Elasticsearch source code
- Replace all existing Apache 2.0 license headers for non-xpack code
with updated header (vendored code with Apache 2.0 headers obviously
remains the same).
- Replace all Elastic license 1.0 headers with new 2.0 header in xpack.
This commit adds the infrastructure to plugin building and loading to
allow one plugin to extend another. That is, one plugin may extend
another by the "parent" plugin allowing itself to be extended through
java SPI. When all plugins extending a plugin are finished loading, the
"parent" plugin has a callback (through the ExtensiblePlugin interface)
allowing it to reload SPI.
This commit also adds an example plugin which uses as-yet implemented
extensibility (adding to the painless whitelist).
