Status

Current state: Under Discussion

Discussion thread: 

JIRA: Unable to render Jira issues macro, execution error.

Released: -

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast). Confluence supports inline comments that can also be used.

Motivation

Use a standardized dependency injection in Solr instead of our home grown @SolrCoreAware, @ResourceLoaderAware, @SchemaAware etc.

Proposal is to do a trial with Dagger2 (https://github.com/google/dagger) which is a compile-time depenency injection framework.

Public Interfaces

Many plugins will change API which will affect back-compat.

Proposed Changes

Introduce a well supported IOC/DI framework to gradually replace the home-grown interfaces which are brittle (see Unable to render Jira issues macro, execution error. , Unable to render Jira issues macro, execution error. https://github.com/apache/solr/blob/main/solr/core/src/java/org/apache/solr/core/SolrResourceLoader.java#L815-L816)

This will be a large change across the entire code base. Dagger will scan the codebase for annotations and generate new Java code that will be used run-time.

The exact scope is still unclear, but we recommend starting with a small module or one interface.

Compatibility, Deprecation, and Migration Plan

• Users will not notice anything
• Developers and 3rd party plugin providers may need to re-write their plugins
• The change is breaking and should be introduced in a major version

Security considerations

None

Test Plan

Will be tested implicitly by the test suite.

Rejected Alternatives

• Spring Framework - too intrusive
• Guice - injection happens during runtime
• Improve our own annotations