Request Validation

Plenum validates incoming request bodies against the schemas defined in your OpenAPI spec. Attach the built-in internal:validate-request interceptor to an operation and it automatically uses the schema from the spec’s requestBody — no need to duplicate it.

Working example: see examples/validation/

Configuration

Attach the interceptor to any operation that has a requestBody schema:

actions:
  - target: "$.paths['/items'].post"
    update:
      x-plenum-interceptor:
        - module: "internal:validate-request"
          hook: "on_request"
          function: "validateRequest"

The interceptor reads the schema from the spec’s requestBody.content.application/json.schema automatically, including $ref references to components/schemas.

Behaviour

# Valid request — proxied to backend
$ curl -X POST http://localhost:6188/items \
  -H "Content-Type: application/json" \
  -d '{"name": "Widget", "quantity": 5}'
# => 201

# Missing required field — rejected by gateway
$ curl -X POST http://localhost:6188/items \
  -H "Content-Type: application/json" \
  -d '{"name": "Widget"}'
# => 400 {"type":"request-validation-error","title":"Request Validation Failed",...}

# Wrong type — rejected by gateway
$ curl -X POST http://localhost:6188/items \
  -H "Content-Type: application/json" \
  -d '{"name": "Widget", "quantity": "five"}'
# => 400

What gets validated

The interceptor validates against the JSON Schema from the spec, including:

• Required fields
• Type checking (string, integer, boolean, etc.)
• Additional constraints (enum, pattern, min/max, etc.)
• $ref references to shared schemas in components/schemas

Overriding the schema

To validate against a different schema than the one in the spec, provide an explicit options.schema:

x-plenum-interceptor:
  - module: "internal:validate-request"
    hook: "on_request"
    function: "validateRequest"
    options:
      schema:
        type: object
        properties:
          name:
            type: string
          quantity:
            type: integer
        required:
          - name
          - quantity

When options.schema is provided, it takes precedence over the spec schema.

For response validation, see Response Validation.