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CORS

Easily add Cross-origin resource sharing (CORS) to a Service and a Route by enabling this plugin.

Note: The functionality of this plugin as bundled with versions of Kong prior to 0.10.3 differs from what is documented herein. Refer to the CHANGELOG for details.

Configuration Reference

You can configure this plugin using the Kong Admin API or through declarative configuration, which involves directly editing the Kong configuration file.

This plugin is compatible with requests with the following protocols:

  • http
  • https

This plugin is compatible with DB-less mode.

In DB-less mode, Kong does not have an Admin API. If using this mode, configure the plugin using declarative configuration.

Enabling the plugin on a Service

Kong Admin API
Kubernetes
Declarative (YAML)

For example, configure this plugin on a Service by making the following request:

$ curl -X POST http://<admin-hostname>:8001/services/<service>/plugins \
    --data "name=cors"  \
    --data "config.origins=http://mockbin.com" \
    --data "config.methods=GET" \
    --data "config.methods=POST" \
    --data "config.headers=Accept" \
    --data "config.headers=Accept-Version" \
    --data "config.headers=Content-Length" \
    --data "config.headers=Content-MD5" \
    --data "config.headers=Content-Type" \
    --data "config.headers=Date" \
    --data "config.headers=X-Auth-Token" \
    --data "config.exposed_headers=X-Auth-Token" \
    --data "config.credentials=true" \
    --data "config.max_age=3600"

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <cors-example>
config: 
  origins:
  - http://mockbin.com
  methods:
  - GET
  - POST
  headers:
  - Accept
  - Accept-Version
  - Content-Length
  - Content-MD5
  - Content-Type
  - Date
  - X-Auth-Token
  exposed_headers:
  - X-Auth-Token
  credentials: true
  max_age: 3600
plugin: cors

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

apiVersion: v1
kind: Service
metadata:
  name: <service>
  labels:
    app: <service>
  annotations:
    konghq.com/plugins: <cors-example>
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: <service>
  selector:
    app: <service>
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.

For example, configure this plugin on a Service by adding this section to your declarative configuration file:

plugins:
- name: cors
  service: <service>
  config: 
    origins:
    - http://mockbin.com
    methods:
    - GET
    - POST
    headers:
    - Accept
    - Accept-Version
    - Content-Length
    - Content-MD5
    - Content-Type
    - Date
    - X-Auth-Token
    exposed_headers:
    - X-Auth-Token
    credentials: true
    max_age: 3600

<service> is the id or name of the Service that this plugin configuration will target.

Enabling the plugin on a Route

Kong Admin API
Kubernetes
Declarative (YAML)

For example, configure this plugin on a Route with:

$ curl -X POST http://<admin-hostname>:8001/routes/<route>/plugins \
    --data "name=cors"  \
    --data "config.origins=http://mockbin.com" \
    --data "config.methods=GET" \
    --data "config.methods=POST" \
    --data "config.headers=Accept" \
    --data "config.headers=Accept-Version" \
    --data "config.headers=Content-Length" \
    --data "config.headers=Content-MD5" \
    --data "config.headers=Content-Type" \
    --data "config.headers=Date" \
    --data "config.headers=X-Auth-Token" \
    --data "config.exposed_headers=X-Auth-Token" \
    --data "config.credentials=true" \
    --data "config.max_age=3600"

First, create a KongPlugin resource:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <cors-example>
config: 
  origins:
  - http://mockbin.com
  methods:
  - GET
  - POST
  headers:
  - Accept
  - Accept-Version
  - Content-Length
  - Content-MD5
  - Content-Type
  - Date
  - X-Auth-Token
  exposed_headers:
  - X-Auth-Token
  credentials: true
  max_age: 3600
plugin: cors

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

apiVersion: networking/v1beta1
kind: Ingress
metadata:
  name: <route>
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: <cors-example>
spec:
  rules:
  - host: examplehostname.com
    http:
      paths:
      - path: /bar
        backend:
          serviceName: echo
          servicePort: 80
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.

For example, configure this plugin on a Route by adding this section to your declarative configuration file:

plugins:
- name: cors
  route: <route>
  config: 
    origins:
    - http://mockbin.com
    methods:
    - GET
    - POST
    headers:
    - Accept
    - Accept-Version
    - Content-Length
    - Content-MD5
    - Content-Type
    - Date
    - X-Auth-Token
    exposed_headers:
    - X-Auth-Token
    credentials: true
    max_age: 3600

<route> is the id or name of the Route that this plugin configuration will target.

Enabling the plugin globally

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.

Kong Admin API
Kubernetes
Declarative (YAML)

For example, configure this plugin globally with:

$ curl -X POST http://<admin-hostname>:8001/plugins/ \
    --data "name=cors"  \
    --data "config.origins=http://mockbin.com" \
    --data "config.methods=GET" \
    --data "config.methods=POST" \
    --data "config.headers=Accept" \
    --data "config.headers=Accept-Version" \
    --data "config.headers=Content-Length" \
    --data "config.headers=Content-MD5" \
    --data "config.headers=Content-Type" \
    --data "config.headers=Date" \
    --data "config.headers=X-Auth-Token" \
    --data "config.exposed_headers=X-Auth-Token" \
    --data "config.credentials=true" \
    --data "config.max_age=3600"

Create a KongClusterPlugin resource and label it as global:

apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-cors>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
config: 
  origins:
  - http://mockbin.com
  methods:
  - GET
  - POST
  headers:
  - Accept
  - Accept-Version
  - Content-Length
  - Content-MD5
  - Content-Type
  - Date
  - X-Auth-Token
  exposed_headers:
  - X-Auth-Token
  credentials: true
  max_age: 3600
plugin: cors

For example, configure this plugin using the plugins: entry in the declarative configuration file:

plugins:
- name: cors
  config: 
    origins:
    - http://mockbin.com
    methods:
    - GET
    - POST
    headers:
    - Accept
    - Accept-Version
    - Content-Length
    - Content-MD5
    - Content-Type
    - Date
    - X-Auth-Token
    exposed_headers:
    - X-Auth-Token
    credentials: true
    max_age: 3600

Parameters

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

Form ParameterDescription
name

Type: string		 The name of the plugin to use, in this case cors.
service.id

Type: string		 The ID of the Service the plugin targets.
route.id

Type: string		 The ID of the Route the plugin targets.
enabled

Type: boolean

Default value: true		 Whether this plugin will be applied.
config.origins
optional

List of allowed domains for the Access-Control-Allow-Origin header. If you want to allow all origins, add * as a single value to this configuration field. The accepted values can either be flat strings or PCRE regexes. NOTE: Prior to Kong 0.10.x, this parameter was config.origin (note the change in trailing s), and only accepted a single value, or the * special value.
config.methods
optional

Default value: GET, HEAD, PUT, PATCH, POST, DELETE, OPTIONS, TRACE, CONNECT

Value for the Access-Control-Allow-Methods header.
config.headers
optional

Default value: Value of the Access-Control-Request-Headers request header

Value for the Access-Control-Allow-Headers header.
config.exposed_headers
optional

Value for the Access-Control-Expose-Headers header. If not specified, no custom headers are exposed.
config.credentials
optional

Default value: false

Flag to determine whether the Access-Control-Allow-Credentials header should be sent with true as the value.
config.max_age
optional

Indicates how long the results of the preflight request can be cached, in seconds.
config.preflight_continue
optional

Default value: false

A boolean value that instructs the plugin to proxy the OPTIONS preflight request to the Upstream service.

Known issues

Below is a list of known issues or limitations for this plugin.

CORS Limitations

If the client is a browser, there is a known issue with this plugin caused by a limitation of the CORS specification that doesn’t allow to specify a custom Host header in a preflight OPTIONS request.

Because of this limitation, this plugin only works for Routes that have been configured with a paths setting. The CORS plugin does not work for Routes that are being resolved using a custom DNS (the hosts property).

To learn how to configure paths for a Route, read the Proxy Reference.