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: the Kong entity representing a developer or machine using the API. When using Kong, a Consumer only communicates with Kong which proxies every call to the said upstream API.
• 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

With a database

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}}]"

Without a database

Configure this plugin on a Service by adding this section do your declarative configuration file:

plugins:
- name: request-validator
  service: {service}
  config: 
    body_schema: [{"name":{"type": "string", "required": true}}]

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

Enabling the plugin on a Route

With a database

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}}]"

Without a database

Configure this plugin on a Route by adding this section do your declarative configuration file:

plugins:
- name: request-validator
  route: {route}
  config: 
    body_schema: [{"name":{"type": "string", "required": true}}]

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

Enabling the plugin on a Consumer

With a database

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}}]"

Without a database

Configure this plugin on a Consumer by adding this section do your declarative configuration file:

plugins:
- name: request-validator
  consumer: {consumer}
  config: 
    body_schema: [{"name":{"type": "string", "required": true}}]

In both cases, {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.

Further References

Check out the Kong docs on storing custom entities here.