OpenAPI spec for diagnostics server

[czeslavo]

Is there an existing issue for this?

• I have searched the existing issues

Does this enhancement require public documentation?

• I have added an Acceptance Criteria item for adding and/or adjusting public documentation (if applicable)

Problem Statement

Currently, KIC's diagnostics server is not documented properly. As we started adding more endpoints to it, it might be worth defining it properly using some industry-standard API spec like OpenAPI.

Proposed Solution

• Define OpenAPI 3.0 spec for the existing server
• Adjust the server code by replacing hand-written boilerplate with auto-generated types and server base (e.g. using oapi-codegen)
• Make the spec available from the official docs

Additional information

No response

Acceptance Criteria

• KIC's diagnostics server API is defined in OpenAPI spec
• KIC's diagnostics server boilerplate (types and parts of server) is generated from the spec
• OpenAPI spec is linked in the docs.konghq.com diagnostics server reference