Request Validator

Validate requests before they reach their upstream Service. Supports request body validation, according to a schema. Note: the schema format is NOT JSON schema compliant; instead, Kong’s own schema format is used.

Terminology

• plugin: a plugin executing actions inside Kong before or after a request has been proxied to the upstream API.
• Service: the Kong entity representing an external upstream API or microservice.
• Route: the Kong entity representing a way to map downstream requests to upstream services.
• Consumer: an entity that makes requests for Kong to proxy; it represents either a user or an external service.
• Credential: a unique string associated with a Consumer, also referred to as an API key.
• upstream service: this refers to your own API/service sitting behind Kong, to which client requests are forwarded.

Configuration

Enabling the plugin on a Service

Configure this plugin on a Service by making the following request:

$ curl -X POST http://kong:8001/services/{service}/plugins \
    --data "name=request-validator"  \
    --data "config.body_schema=[{"name":{"type": "string", "required": true}}]" \
    --data "config.version=kong"

{service} is the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

Configure this plugin on a Route with:

$ curl -X POST http://kong:8001/routes/{route}/plugins \
    --data "name=request-validator"  \
    --data "config.body_schema=[{"name":{"type": "string", "required": true}}]" \
    --data "config.version=kong"

{route} is the id or name of the Route that this plugin configuration will target.

Enabling the plugin on a Consumer

You can use the http://localhost:8001/plugins endpoint to enable this plugin on specific Consumers:

$ curl -X POST http://kong:8001/consumers/{consumer}/plugins \
    --data "name=request-validator" \
     \
    --data "config.body_schema=[{"name":{"type": "string", "required": true}}]" \
    --data "config.version=kong"

{consumer} is the id or username of the Consumer that this plugin configuration will target.

You can combine consumer.id and service.id in the same request, to furthermore narrow the scope of the plugin.

Global plugins

• Using a database, all plugins can be configured using the http://kong:8001/plugins/ endpoint.
• Without a database, all plugins can be configured via the plugins: entry on the declarative configuration file.

A plugin which is not associated to any Service, Route or Consumer (or API, if you are using an older version of Kong) is considered "global", and will be run on every request. Read the Plugin Reference and the Plugin Precedence sections for more information.

Parameters

Here's a list of all the parameters which can be used in this plugin's configuration:

Examples

Overview

By applying the plugin to a Service, all requests to that Service will be validated before being proxied.

With a database

Use a request like this:

curl -i -X POST http://kong:8001/services/{service}/plugins \
  --data "name=request-validator" \
  --data 'config.body_schema=[{"name":{"type": "string", "required": true}}]'

Without a database

Add the following entry to the plugins: section in the declarative configuration file:

plugins:
- name: request-validator
  service: {service}
  config:
    body_schema:
      name:
        type: string
        required: true

The parameters/fields in both cases mean:

In this example, the request body data would have to be a valid JSON and conform to the schema specified in body_schema - i.e., it would be required to contain a name field only, which needs to be a string.

Schema Definition

The config.body_schema field expects a JSON array with the definition of each field expected to be in the request body; for example:

Each field definition contains the following attributes:

Additionally, specific types may have their own required fields:

Map:

Example string-boolean map:

{
  "type": "map",
  "keys": {
    "type": "string"
  },
  "values": {
    "type": "boolean"
  }
}

Array:

Example integer array schema:

{
  "type": "array",
  "elements": {
    "type": "integer"
  }
}

Record:

Example record schema:

{
  "type": "record",
  "fields": [
    {
      "street": {
        "type": "string",
      }
    },
    {
      "zipcode": {
        "type": "string",
      }
    }
  ]
}

The type field assumes one the following values:

• string
• number
• integer
• boolean
• map
• array
• record

Each field specification may also contain “validators”, which perform specific validations:

Note: check this out to learn about Lua patterns.

Schema Example

[
  {
    "name": {
      "type": "string",
      "required": true
    }
  },
  {
    "age": {
        "type": "integer",
        "required": true
      }
  },
  {
    "address": {
      "type": "record",
      "required": true,
      "fields": [
        {
          "street": {
            "type": "string",
            "required": true
          }
        },
        {
          "zipcode": {
            "type": "string",
            "required": true
          }
        }
      ]
    }
  }
]

Such a schema would validate the following request body:

{
  "name": "Gruce The Great",
  "age": 4,
  "address": {
    "street": "251 Post St.",
    "zipcode": "94108"
  }
}

In case either the JSON or schema validation fail, a 400 Bad Request will be returned as response.

Parameter Schema Definition

You can setup definitions for each parameter based of the OpenAPI Specification and the plugin will validate each parameter against it. For more information see the OpenAPI spec or the OpenAPI examples.

Fixed Fields

Examples

In this example we will use the plugin to validate a request’s path parameter.

1. Add a service to Kong

   curl -i -X POST http://kong:8001/services \
     --data name=httpbin \
     --data url=http://httpbin.org
   
   HTTP/1.1 201 Created
   ..
   
   {
     "host":"httpbin.org",
     "created_at":1563479714,
     "connect_timeout":60000,
     "id":"0a7f3795-bc92-43b5-aada-258113b7c4ed",
     "protocol":"http",
     "name":"httpbin",
     "read_timeout":60000,
     "port":80,
     "path":null,
     "updated_at":1563479714,
     "retries":5,
     "write_timeout":60000
   }
   

2. Add a route with named capture group

   curl -i -X POST http://kong:8001/services/httpbin/routes \
     --data paths="/status/(?<status_code>\d%+)" \
     --data strip_path=false
   
   HTTP/1.1 201 Created
   ..
   
   {
     "created_at": 1563481399,
     "methods": null,
     "id": "cd78749a-33a3-4bbd-9560-588eaf4116d3",
     "service": {
       "id": "0a7f3795-bc92-43b5-aada-258113b7c4ed"
     },
     "name": null,
     "hosts": null,
     "updated_at": 1563481399,
     "preserve_host": false,
     "regex_priority": 0,
     "paths": [
       "\\/status\\/(?<status_code>\\d+)"
     ],
     "sources": null,
     "destinations": null,
     "snis": null,
     "protocols": [
       "http",
       "https"
     ],
     "strip_path": false
   }
   

3. Enable request-validator plugin to validate body and parameter

    curl -i -X POST http://kong:8001/services/httpbin/plugins \
      --header "Content-Type: application/json" \
      --data @parameter_schema.json
   
    HTTP/1.1 201 Created
    ..
   
    {
      "created_at": 1563483059,
      "config": {
        "body_schema": "{\"name\":{\"type\": \"string\", \"required\": false}}",
        "parameter_schema": [
          {
            "style": "simple",
            "required": true,
            "in": "path",
            "schema": "{\"type\": \"number\"}",
            "explode": false,
            "name": "status_code"
          }
        ],
        "version": "draft4"
      },
      "id": "ad91a2d4-6217-4d34-9133-4a2508ddda9f",
      "service": {
        "id": "0a7f3795-bc92-43b5-aada-258113b7c4ed"
      },
      "enabled": true,
      "run_on": "first",
      "consumer": null,
      "route": null,
      "name": "request-validator"
    }
   

   content of file parameter_schema.json

    {
      "name": "request-validator",
      "config": {
        "body_schema": "{\"name\":{\"type\": \"string\", \"required\": false}}",
        "version": "draft4",
        "parameter_schema": [
          {
            "name": "status_code",
            "in": "path",
            "required": true,
            "schema": "{\"type\": \"number\"}",
            "style": "simple",
            "explode": false
          }
        ]
      }
    }
   

   Here validation will make sure status_code is a number.

4. A proxy request with a non-numerical status code will be blocked

    curl -i -X GET http://kong:8000/status/abc
    HTTP/1.1 400 Bad Request
    ..
   
    {"message":"request param doesn't conform to schema"}
   

   but it will be allowed with a numeric status code

    curl -i -X GET http://kong:8000/status/200
    HTTP/1.1 200 OK
    X-Kong-Upstream-Latency: 163
    X-Kong-Proxy-Latency: 37
    ..
   
   

Further References

Check out the Kong docs on storing custom entities here.