[FEATURE] Generate API code from OpenSearch OpenAPI Spec

[Xtansia]

Is your feature request related to a problem?

Related to opensearch-project/opensearch-clients#19

What solution would you like?

Re-use the existing generator that generates API Code that maintains backwards compatibility with the current client APIs and provides a way to add new APIs.

Existing generator exists here: https://github.com/opensearch-project/opensearch-rs/tree/main/api_generator

It should be modified so that it parses the OpenAPI specification from https://github.com/opensearch-project/opensearch-api-specification/blob/main/OpenSearch.openapi.json instead of the legacy "rest specs".

There's some documentation about how the specs map onto the generated code here: https://github.com/opensearch-project/opensearch-api-specification/blob/main/CLIENT_GENERATOR_GUIDE.md

What alternatives have you considered?

Using OpenAPI generators instead of re-using the existing generator but it makes it difficult to maintain backwards compatibility.

Do you have any additional context?

Add any other context or screenshots about the feature request here.

[AbhinavGarg90]

Coming from #190, I'm interested to work on this. I am not sure where I start though. Is there anywhere you suggest I start reading to try to understand how to approach this?

[Xtansia]

Various clients have already made this conversion from old specs to OpenAPI:

• Ruby: https://github.com/opensearch-project/opensearch-ruby/blob/main/api_generator/lib/api_generator.rb#L42-L54
• Python: https://github.com/opensearch-project/opensearch-py/blob/main/utils/generate-api.py#L439-L647
• .NET/C#: https://github.com/opensearch-project/opensearch-net/blob/main/src/ApiGenerator/Generator/ApiGenerator.cs#L93-L107