Pass ExtensionsRunner instance to createComponents

[dbwiddis]

Description

Guice has not finished initializing the injector when calling createComponents as the return objects need to be injected. Components which require objects from the ExtensionsRunner for instantiation need a copy of them available.

While the constructor could be filled with a long list of these parameters (as is done in plugins) this creates a hard API dependency on the parameters, and changing the number of parameters would break compatibility.

By passing the ExtensionsRunner, additional objects can be made available via getters without changing the API.

Issues Resolved

Improves on #466

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[codecov-commenter]

Codecov Report

Merging #477 (afefeae) into main (8f3bcde) will increase coverage by 0.20%.
The diff coverage is 100.00%.

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@@             Coverage Diff              @@
##               main     #477      +/-   ##
============================================
+ Coverage     65.96%   66.17%   +0.20%     
- Complexity      183      186       +3     
============================================
  Files            35       35              
  Lines           808      813       +5     
  Branches         24       24              
============================================
+ Hits            533      538       +5     
  Misses          264      264              
  Partials         11       11              

Impacted Files	Coverage Δ
src/main/java/org/opensearch/sdk/Extension.java	100.00% <ø> (ø)
...main/java/org/opensearch/sdk/ExtensionsRunner.java	70.76% <100.00%> (+0.88%)	⬆️

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[owaiskazi19]

We might need to revisit this logic while working on #467. Approved for now.

[dbwiddis]

We might need to revisit this logic while working on #467.

Agreed. Here's the overall logical constraints (which probably should find its way into code comments):

Order matters:

1. Initialize concrete classes needed by create components. If these are things that may change during operation (e.g. NamedXContents) use a concrete wrapper class with the ability to update its internals.
2. Inject classes (any order, Guice figures out the dependency map later)
   • Inject the concrete classes. Since they aren't yet available to create components, make sure they have getters and then just pass the runner to create components. Injecting them using the getters is a subtle reminder of this. :)
   • Inject the objects returned from create components.
   • Inject any other extension points that require injection (in this case getActions).
3. After injection, call other extension points (e.g., rest handlers). This permits these other extension points to have access to the injected classes.