Propagate Headers and Context through to ScriptService

[colings86]

At the moment if an index script is used in a request, the spawned request to get the indexed script from the .scripts index does not get the headers and context copied to it from the original request. This change makes the calls to the ScriptService pass in a HasContextAndHeaders object that can provide the headers and context. For the search() method the context and headers are retrieved from SearchContext.current().

Closes #12891

[spinscale]

can we add tests to ContextAndHeaderTransportIT for testing this?

[colings86]

@spinscale I added a couple of tests to check that the headers and context are propagated for the TemplateQuery and for the reduce phase of aggregations.

[spinscale]

overall this looks good to me, but

• I couldnt run mvn test due to forbidden API errors, is it me?
• Can we add a test for the phrase suggesters as it has been changed?
• Thinking if we can reuse the DelegatingHasContextAndHeaders in our SearchContext (might be tricky with the inheritance though)

[colings86]

@spinscale I have implemented the suggested changes and rebased onto master (without squashing commits), are you able to take another look?

[spinscale]

with this change in place, can you try to remove the HasContextAndHeaders delegation methods from PercolateContext and FilteredSearchContext?

[spinscale]

left one last comment, I am not sure if you can remove all the methods (having the asserts in the percolate context seems useful to me), but maybe you can remove some code...

apart from that LGTM

[colings86]

I was able to remove the methods from FilteredSearchContext but I kept them in PercolateContext as I think the asserts are important to have.