Get Extension API during initialization

[dbwiddis]

Signed-off-by: Daniel Widdis [email protected]

Description

(This is a draft PR submitted for review/feedback of initial approach. Please wait until all sub-issues are complete before merging.)

Companion PR: opensearch-project/OpenSearch#4056

Extensions will report their APIs to the ExtensionsOrchestrator during initialization. These APIs will be registered and mapped so that when Users submit API requests they can be forwarded to the appropriate extensions.

Issues Resolved

Meta issue #64

• Fixes [FEATURE] Send required REST APIs to OpenSearch #68
• Fixes [FEATURE] Register REST API and map to associated extension in ExtensionsOrchestrator #69
• Fixes [FEATURE] Redirect REST API request to appropriate extensions #70

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[dbwiddis]

Current output from extension:

         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 45 53 00 00 00 2d 00 00 00 00 00 00 00 03 01 08 |ES...-..........|
|00000010| 2d c7 23 00 00 00 02 00 00 09 65 78 74 65 6e 73 |-.#.......extens|
|00000020| 69 6f 6e 03 04 41 50 49 31 04 41 50 49 32 04 41 |ion..API1.API2.A|
|00000030| 50 49 33                                        |PI3             |
+--------+-------------------------------------------------+----------------+

Current output from OpenSearch:

Received API from extension: [API1, API2, API3]

[dbwiddis]

Based on feedback regarding future flexibility as mentioned in #68, closing this. Will start over with a different approach.