WebSocket Validator plugin

Validate individual WebSocket messages against to a user-specified schema before proxying them.

Message schema can be configured by type (text or binary) and sender (client or upstream).

When an incoming message is invalid according to the schema, a close frame is sent to the sender (status: 1007) and the peer before closing the connection.

Configuration Reference

This plugin is compatible with DB-less mode.

In DB-less mode, you configure Kong Gateway declaratively. Therefore, the Admin API is mostly read-only. The only tasks it can perform are all related to handling the declarative config, including:

Setting a target's health status in the load balancer
Validating configurations against schemas
Uploading the declarative configuration using the /config endpoint

Example plugin configuration

Enable on a service

Enable on a route

Enable globally

The following examples provide some typical configurations for enabling the websocket-validator plugin on a service.

Admin API

Kubernetes

Declarative (YAML)

Konnect Cloud

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/services/SERVICE_NAME|SERVICE_ID/plugins \
    --data "name=websocket-validator"  \
    --data 'config.client.text.schema={ "type": "object" }' \
    --data 'config.client.text.type=draft4'

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: websocket-validator-example
config: 
  client:
    text:
    schema: '{ "type": "object" }'
  client:
    text:
    type: 'draft4'
plugin: websocket-validator

Next, apply the KongPlugin resource to a service by annotating the service as follows:

apiVersion: v1
kind: Service
metadata:
  name: SERVICE_NAME|SERVICE_ID
  labels:
    app: SERVICE_NAME|SERVICE_ID
  annotations:
    konghq.com/plugins: websocket-validator-example
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: SERVICE_NAME|SERVICE_ID
  selector:
    app: SERVICE_NAME|SERVICE_ID

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

Note: The KongPlugin resource only needs to be defined once and can be applied to any service, consumer, or route in the namespace. If you want the plugin to be available cluster-wide, create the resource as a KongClusterPlugin instead of KongPlugin.

Add this section to your declarative configuration file:

plugins:
- name: websocket-validator
  service: SERVICE_NAME|SERVICE_ID
  config: 
    client:
      text:
      schema: '{ "type": "object" }'
    client:
      text:
      type: 'draft4'

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

You can configure this plugin through the Konnect UI.

From the Service Hub, select a service version, then set up the plugin:

In the Plugins section, click Add Plugin.
Find and select the WebSocket Validator plugin.
Click Create.

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
From the Services section, click View for the service row.
From the plugin section, click Add Plugin.
Find and select the WebSocket Validator plugin.
Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
If the option is available, select Scoped.
Add the service name and ID to the Service field if it is not already pre-filled.
Click Create.

The following examples provide some typical configurations for enabling the websocket-validator plugin on a route.

Admin API

Kubernetes

Declarative (YAML)

Konnect Cloud

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/routes/ROUTE_NAME|ROUTE_ID/plugins \
  --data "name=websocket-validator"  \
    --data 'config.client.text.schema={ "type": "object" }' \
    --data 'config.client.text.type=draft4'

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: websocket-validator-example
config: 
  client:
    text:
    schema: '{ "type": "object" }'
  client:
    text:
    type: 'draft4'
plugin: websocket-validator

Then, apply it to an ingress (route or routes) by annotating the ingress as follows:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ROUTE_NAME|ROUTE_ID
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: websocket-validator-example
spec:
  rules:
  - host: examplehostname.com
    http:
      paths:
      - path: /bar
        backend:
          service:
            name: echo
            port:
              number: 80

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

Note: The KongPlugin resource only needs to be defined once and can be applied to any service, consumer, or route in the namespace. If you want the plugin to be available cluster-wide, create the resource as a KongClusterPlugin instead of KongPlugin.

Add this section to your declarative configuration file:

plugins:
- name: websocket-validator
  route: ROUTE_NAME
  config: 
    client:
      text:
      schema: '{ "type": "object" }'
    client:
      text:
      type: 'draft4'

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

You can configure this plugin through the Konnect UI.

From the Service Hub, select a service version, then set up the plugin:

Select a route.
In the Plugins section, click Add Plugin.
Find and select the WebSocket Validator plugin.
Click Create.

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
Open Routes from the menu, then click View for the route row.
From the plugin section, click Add Plugin.
Find and select the WebSocket Validator plugin.
Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
If the option is available, select Scoped.
Add the route ID if it is not already prefilled.
Click Create.

A plugin which is not associated to any service, route, or consumer is considered global, and will be run on every request. Read the Plugin Reference and the Plugin Precedence sections for more information.

The following examples provide some typical configurations for enabling the websocket-validator plugin globally.

Admin API

Kubernetes

Declarative (YAML)

Kong Manager

Make the following request:

curl -X POST http://localhost:8001/plugins/ \
  --data "name=websocket-validator"  \
    --data 'config.client.text.schema={ "type": "object" }' \
    --data 'config.client.text.type=draft4'

Create a KongClusterPlugin resource and label it as global:

apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-websocket-validator>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
config: 
  client:
    text:
    schema: '{ "type": "object" }'
  client:
    text:
    type: 'draft4'
plugin: websocket-validator

Add a plugins entry in the declarative configuration file:

plugins:
- name: websocket-validator
  config: 
    client:
      text:
      schema: '{ "type": "object" }'
    client:
      text:
      type: 'draft4'

You can configure this plugin through the Kong Manager UI.

In Kong Manager, select the workspace.
Open Plugins from the menu, then click New Plugin.
Find and select the WebSocket Validator plugin.
Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
If the option is available, set the plugin scope to Global.
Click Create.

Parameters

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

Form Parameter	Description
`name` required Type: string	The name of the plugin, in this case `websocket-validator`.
`service.name` or `service.id` Type: string	The name or ID of the service the plugin targets. Set one of these parameters if adding the plugin to a service through the top-level `/plugins` endpoint. Not required if using `/services/SERVICE_NAME\|SERVICE_ID/plugins`.
`route.name` or `route.id` Type: string	The name or ID of the route the plugin targets. Set one of these parameters if adding the plugin to a route through the top-level `/plugins` endpoint. Not required if using `/routes/ROUTE_NAME\|ROUTE_ID/plugins`.
`enabled` Type: boolean Default value: `true`	Whether this plugin will be applied.
`config.client.text.schema` semi-optional Type: string	Schema used to validate client-originated text frames. The semantics of this field depend on the validation type set by `config.client.text.type`.
`config.client.text.type` semi-optional Type: string	The corresponding validation library for `config.client.text.schema`. Currently, only `draft4` is supported.
`config.client.binary.schema` semi-optional Type: string	Schema used to validate client-originated binary frames. The semantics of this field depend on the validation type set by `config.client.binary.type`.
`config.client.binary.type` semi-optional Type: string	The corresponding validation library for `config.client.binary.schema`. Currently, only `draft4` is supported.
`config.upstream.text.schema` semi-optional Type: string	Schema used to validate upstream-originated text frames. The semantics of this field depend on the validation type set by `config.upstream.text.type`.
`config.upstream.text.type` semi-optional Type: string	The corresponding validation library for `config.upstream.text.schema`. Currently, only `draft4` is supported.
`config.upstream.binary.schema` semi-optional Type: string	Schema used to validate upstream-originated binary frames. The semantics of this field depend on the validation type set by `config.upstream.binary.type`.
`config.upstream.binary.type` semi-optional Type: string	The corresponding validation library for `config.upstream.binary.schema`. Currently, only `draft4` is supported.

At least one of the following complete message validation configurations must be defined:

config.client.text.type and config.client.text.schema
config.client.binary.type and config.client.binary.schema
config.upstream.text.type and config.upstream.text.schema
config.upstream.binary.type and config.upstream.binary.schema

Usage

Note: Currently, the only supported validation type is JSON schema draft4, so all examples will use this.

Validate client text frames

This example validates that client text frames:

Are valid JSON
Are a JSON object ({})
Have a name attribute (of any type)

With a database

Without a database

curl -i -X POST http://HOSTNAME:8001/services/SERVICE/plugins \
  --data "name=websocket-validator" \
  --data "config.client.text.type=draft4" \
  --data 'config.client.text.schema={ "type": "object", "required": ["name"] }'

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

plugins:
- name: websocket-validator
  service: SERVICE
  config:
    client:
      text:
        type: draft4
        schema: |
          {
            "type": "object",
            "required": [ "name" ]
          }

Here’s an example sequence for this configuration:

 .------.                               .----.                          .--------.
 |Client|                               |Kong|                          |Upstream|
 '------'                               '----'                          '--------'
    |                                     |                                 |
    |     text(`{ "name": "Alex" }`)      |                                 |
    |>----------------------------------->|                                 |
    |                                     |                                 |
    |                                     |    text(`{ "name": "Alex" }`)   |
    |                                     |>------------------------------->|
    |                                     |                                 |
    |     text(`{ "name": "Kiran" }`)     |                                 |
    |>----------------------------------->|                                 |
    |                                     |                                 |
    |                                     |   text(`{ "name": "Kiran" }`)   |
    |                                     |>------------------------------->|
    |                                     |                                 |
    |  text(`{ "missing_name": true }`)   |                                 |
    |>----------------------------------->|                                 |
    |                                     |                                 |
    |         close(status=1007)          |                                 |
    |<-----------------------------------<|                                 |
    |                                     |                                 |
    |                                     |             close()             |
    |                                     |>------------------------------->|
 .------.                               .----.                          .--------.
 |Client|                               |Kong|                          |Upstream|
 '------'                               '----'                          '--------'

About this Plugin
Plugin Version	3.0.x
Made by	Kong Inc.
Categories	Traffic Control
DB-less compatible?	Yes
Konnect Cloud compatible?	Yes
Compatible protocols	`ws` `wss`