OAS Validation

Looking for the plugin's configuration parameters? You can find them in the OAS Validation configuration reference doc.

Validate HTTP requests and responses against an OpenAPI Specification.

The plugin supports both Swagger (v2) and OpenAPI (3.0.x and 3.1.0) specifications with a JSON Schema validator that supports Draft 2019-09.

In Kong Gateway versions 3.1.0.0-3.1.1.1, this plugin is not enabled by default. Upgrade to 3.1.1.2, or manually enable the plugin.

Supported OpenAPI 3.1.0 specification features

Tutorial

This example tutorial steps you through ensuring an API request conforms to the associated API specification. This example uses the sample Petstore spec.

1. Create a service called Petstore-Service:

    curl -X POST http://localhost:8001/services/ \
        --data name='Petstore-Service' \
        --data url='https://petstore.swagger.io/v2'
   

2. Create a wildcard route called Petstore-Route:

    curl -X POST http://localhost:8001/services/Petstore-Service/routes \
        --data name='Petstore-Route' \
        --data paths='~/.*' \
        --data strip_path=false
   

3. Enable the Validation plugin on the service you configured:

    curl -X POST http://localhost:8001/services/Petstore-Service/plugins \
        --data name='oas-validation' \
        --data config.api_spec='<copy contents of https://petstore.swagger.io/v2/swagger.json here>' \
        --data config.verbose_response=true
   

4. Test the Validation plugin. The request resource expects a status query parameter, which is missing from the following request:

    curl -X GET "http://localhost:8000/pet/findByStatus" \
      -H "accept: application/json"
   

   The response includes a verbose error response, since we have enabled this option in the plugin configuration:

    HTTP/1.1 400 Bad Request
    Content-Length: 106
    Content-Type: application/json; charset=utf-8
    Date: Tue, 03 May 2022 20:45:00 GMT
    Server: kong/2.8.0.0-internal-preview-enterprise-edition
    X-Kong-Response-Latency: 2
   
    {
      "message": "query 'status' validation failed with error: 'required parameter value not found in request'"
    }
   

Event hooks

Event hooks are outbound calls from Kong Gateway. With event hooks, Kong Gateway can communicate with target services or resources, letting the target know that an event was triggered. Refer to the event hooks example documentation for more information on event hooks.

For the Validation plugin, event hook events can be enabled when a Validation fails for all request parameters, that is URI, Header, & Query parameters and Request body, and/or for Response body from the Upstream Service.

1. Add an event hook for the Validation plugin:

   curl -i -X POST http://{HOSTNAME}:8001/event-hooks \
     -d source=oas-validation \
     -d event=validation-failed \
     -d handler=webhook \
     -d config.url={WEBHOOK_URL}
   

   Response:

   HTTP/1.1 201 Created
   ..
   
   {
       "config": {
           "headers": {},
           "url": {WEBHOOK_URL},
           "ssl_verify": false,
           "secret": null
       },
       "id": "3fe43989-6cf1-4936-bd5d-b7774ca52ad8",
       "source": "oas-validation",
       "event": "validation-failed",
       "handler": "webhook",
       "snooze": null,
       "on_change": null,
       "created_at": 1649732398
    }
   

2. Force a validation failure to a service or route to which the Validation plugin is applied. The Webhook URL will receive a response with JSON payload.

   The following is an example JSON response which includes the forwarded IP address, service, consumer, and error message:

    {
    "ip": "10.0.2.2",
    "source": "oas-validation",
    "err": "query 'status' validation failed with error: 'required parameter value not found in request'",
    "event": "validation-failed",
    "service": {
        "ws_id": "7eebecc0-064e-4890-99cf-0c816280a68e",
        "enabled": true,
        "retries": 5,
        "read_timeout": 60000,
        "protocol": "https",
        "id": "6792ec72-67b2-4960-96b1-e7564dda3178",
        "connect_timeout": 60000,
        "name": "petstore-service",
        "port": 443,
        "host": "petstore.swagger.io",
        "updated_at": 1649391578,
        "path": "/v2/",
        "write_timeout": 60000,
        "created_at": 1647993371
    },
    "consumer": {}
    }
   

Troubleshooting

The plugin validates the ETag header with the If-Match header

If a request contains the If-Match request header, the OAS Validation plugin follows RFC 2616 to validate the Etag response header.

If you don’t want the plugin to validate the Etag with the If-Match request header, send the If-Match header with a wildcard (*) to skip validation.

For example:

curl http://localhost:8000/example-route \
  -H 'If-Match:*'