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CORS

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

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

Enable the plugin on a service

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

curl -X POST http://{HOST}: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" \
    --data "config.preflight_continue=false"

SERVICE is 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: <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
  preflight_continue: false
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}

{SERVICE} is 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.

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
    preflight_continue: false

SERVICE is the id or name of the service that this plugin configuration will target.

Configure this plugin on a service:

  1. In Konnect Cloud, select the service on the ServiceHub page.
  2. Scroll down to Versions and select the version.
  3. Scroll down to Plugins and click New Plugin.
  4. Find and select the CORS plugin.

  5. Enter the following parameters, updating the default or sample values as needed:

    • Config.Credentials: select checkbox
    • Config.Preflight Continue: clear checkbox
  6. Click Create.

Configure this plugin on a service:

  1. In Kong Manager, select the workspace.
  2. From the Dashboard, scroll down to Services and click View for the service row.
  3. Scroll down to plugins and click Add Plugin.

  4. Find and select the CORS plugin.

    Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
  5. If the option is available, select Scoped.
  6. Add the service name and ID to the Service field if it is not already prefilled.

  7. Enter the following parameters, updating the default or sample values as needed:

    • Config.Credentials: select checkbox
    • Config.Preflight Continue: clear checkbox
  8. Click Create.

Enable the plugin on a route

For example, configure this plugin on a route with:

$ curl -X POST http://{HOST}: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" \
    --data "config.preflight_continue=false"

ROUTE is 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: <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
  preflight_continue: false
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

ROUTE is 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.

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
    preflight_continue: false

ROUTE is the id or name of the route that this plugin configuration will target.

Configure this plugin on a route:

  1. In Konnect Cloud, select the service from the ServiceHub page.
  2. Scroll down to Versions and select the version.
  3. Select the route.
  4. Scroll down to Plugins and click Add Plugin.
  5. Find and select the CORS plugin.

  6. Enter the following parameters, updating the default or sample values as needed:

    • Config.Credentials: select checkbox
    • Config.Preflight Continue: clear checkbox
  7. Click Create.

Configure this plugin on a route:

  1. In Kong Manager, select the workspace.
  2. From the Dashboard, select Routes in the left navigation.
  3. Click View for the route row.
  4. Scroll down to plugins and click Add Plugin.

  5. Find and select the CORS plugin.

    Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
  6. If the option is available, select Scoped.
  7. Add the Route ID if it is not already prefilled.

  8. Enter the following parameters, updating the default or sample values as needed:

    • Config.Credentials: select checkbox
    • Config.Preflight Continue: clear checkbox
  9. Click Create.

Enable 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.

For example, configure this plugin globally with:

$ curl -X POST http://{HOST}: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" \
    --data "config.preflight_continue=false"

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
  preflight_continue: false
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
    preflight_continue: false

Configure this plugin globally:

  1. In Kong Manager, select the workspace.
  2. From the Dashboard, select Plugins in the left navigation.
  3. Click New Plugin.

  4. Find and select the CORS plugin.

    Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
  5. If the option is available, set the plugin scope to Global.

  6. Enter the following parameters, updating the default/sample values as needed:

    • Config.Credentials: select checkbox
    • Config.Preflight Continue: clear checkbox
  7. 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 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
required

Type: boolean

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

Type: array of string elements

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.
config.methods
optional

Type: array of string elements

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

Value for the Access-Control-Allow-Methods header. Available options include GET, HEAD, PUT, PATCH, POST, DELETE, OPTIONS, TRACE, CONNECT. By default, all options are allowed.
config.headers
optional

Type: array of string elements

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

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

Type: array of string elements

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

Type: boolean

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

Type: number

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

Type: boolean

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.