[Fleet] Differences between Output API spec and what is returned by the API

[taylor-swanson]

While working on updating the terraform provider for fleet, I noticed that when moving to v8.10.0 of the OpenAPI spec (https://raw.githubusercontent.com/elastic/kibana/v8.10.0/x-pack/plugins/fleet/common/openapi/bundled.json), there's a mismatch between what the spec claims the schema should be, and what is actually returned by the API.

The 8.10.0 and later schema seems to remove embedding the output data in an item object, but the API still returns the pre-8.10.0 style, where the output object is embedded in an item object.

In the terraform provider project, we are using the following paths/methods:

• GET /outputs/{outputId} (Affected)
• PUT /outputs/{outputId} (Affected)
• POST /outputs (Not affected)
• DELETE /outputs/{outputId} (Not affected)

So from what I can tell, only the GET and PUT methods are affected by this.

Before 8.10.0:

"/outputs/{outputId}": {
      "get": {
        "summary": "Get output by ID",
        "tags": [
          "Outputs"
        ],
        "responses": {
          "200": {
            "description": "OK",
            "content": {
              "application/json": {
                "schema": {
                  "type": "object",
                  "properties": {
                    "item": {
                      "$ref": "#/components/schemas/output"
                    }
                  },
                  "required": [
                    "item"
                  ]
                }
              }
            }
          },
          "400": {
            "$ref": "#/components/responses/error"
          }
        },
        "operationId": "get-output"
      },

In 8.10.0 and later:

"/outputs/{outputId}": {
  "get": {
    "summary": "Get output by ID",
    "tags": [
      "Outputs"
    ],
    "responses": {
      "200": {
        "description": "OK",
        "content": {
          "application/json": {
            "schema": {
              "$ref": "#/components/schemas/output_create_request"
            }
          }
        }
      },
      "400": {
        "$ref": "#/components/responses/error"
      }
    },
    "operationId": "get-output"
  }
}

I'm not sure if dropping the output type in favor of output_create_request was intentional, but when I at least account for the item issue, I can unmarshal responses seemingly okay, so I don't think that is a major issue.

Here's what's returned by the API on 8.10.2:

GET https://localhost:5601/api/fleet/outputs/fleet-default-output

{
    "item": {
        "id": "fleet-default-output",
        "name": "default",
        "type": "elasticsearch",
        "hosts": [
            "https://elasticsearch:9200"
        ],
        "ca_trusted_fingerprint": "F22AC4B76227ABA21D6CD2616D184FFF980106C4DBB5EEDBA84A7AE21797B47D",
        "is_default": true,
        "is_default_monitoring": true,
        "is_preconfigured": true,
        "config_yaml": null,
        "ca_sha256": null
    }
}

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[juliaElastic]

This change was introduced when adding kafka output, I think this is a mistake in openapi spec, the API itself hasn't changed (still having output wrapped in item).
So I think this is a bug we should fix cc @kpollich