How to map requests to the openapi examples

[jbadeau]

One can leverage WireMock's robust proxy stub mappings features to proxy requests to specific Prism mocks based on the request details.

Wiremock proxy stub mapping

{
  "request": {
    "method": "GET",
    "urlPattern": "/scorecards/default/application/techradar"
  },
  "response": {
    "proxyBaseUrl": "http://127.0.0.1:4010",
    "additionalProxyRequestHeaders": {
      "Prefer": "techradar"
    }
  }
}

In this example, WireMock acts as a simple proxy. It forwards a request for a scorecard (with namespace: default, kind: application, name: techradar) to Prism and adds the Prefer header to techradar, which corresponds to the example name.

OpenApi 3.x response examples

  /scorecards/{namespace}/{kind}/{name}:
    get:
      summary: Retrieve scorecard for a specific entity
      description: Get the scorecard for a specific entity identified by its kind, namespace, and name triple.
      operationId: getScorecard
      parameters:
        - name: namespace
          in: path
          description: Namespace of the entity
          required: true
          schema:
            type: string
            default: default
            examples:
              - default
        - name: kind
          in: path
          description: Type of the entity
          required: true
          schema:
            type: string
            examples:
              - application
        - name: name
          in: path
          description: Name of the entity
          required: true
          schema:
            type: string
            examples:
              -
      responses:
        "200":
          description: Scorecard for the requested entityRef
          content:
            application/hal+json:
              schema:
                $ref: "#/components/schemas/Scorecard"
              examples:
                sda:
                  $ref: "./examples/getScorecard.sda.json"
                techradar:
                  $ref: "./examples/getScorecard.techradar.json"

More complex mappings are of course easily supported. For example, utilizing Wiremock’s support for Handlebars one can:

{
  "request": {
    "method": "GET",
    "urlPattern": "/scorecards/default/application/([^/]+)"
  },
  "response": {
    "proxyBaseUrl": "http://127.0.0.1:4010",
    "additionalProxyRequestHeaders": {
      "Prefer": "{{request.pathSegments.[4]}}"
    },
    "transformers": ["response-template"]
  }
}

Originally posted by @jbadeau in #1838

[jbadeau]

I understand using a competitor like Wiremock might not be ideal but it works well and is relatively easy to do. Perhaps some server middleware is required to make it all easier and more natural.

[alexplayer15]

Hi, we are currently using Prism to run contract tests and it would be great to have a feature where we can auto populate requests based off example values in our OAS.

If I've understood correctly WireMock is currently a workaround for this and not the ideal solution? I am happy to try and add native support for auto-populating request values inside Prism.

Would you want it to look something like this?:

You can run Prism CLI:
prism proxy --auto-populate-request (some new flag in the CLI)

And then when a request is sent to Prism, if it has any missing values in the header/body they are populated based on the examples in the Spec?