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The Forward Proxy plugin allows Kong to connect to intermediary transparent HTTP proxies, instead of directly to the upstream_url, when forwarding requests upstream. This is useful in environments where Kong sits in an organization’s internal network, the upstream API is available via the public internet, and the organization proxies all outbound traffic through a forward proxy server.


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.
  • API: a legacy entity used to represent your upstream services. Deprecated in favor of Services since CE 0.13.0 and EE 0.32.

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=forward-proxy" 

  • service: 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_id}/plugins \
    --data "name=forward-proxy" 

  • route_id: the id 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/plugins \
    --data "name=forward-proxy" \
    --data "consumer_id={consumer_id}" 

Where consumer_id is the id of the Consumer we want to associate with this plugin.

You can combine consumer_id and service_id

in the same request, to furthermore narrow the scope of the plugin.

Enabling the plugin on an API

If you are using an older version of Kong with the legacy API entity (deprecated in favor of Services since CE 0.13.0 and EE 0.32.), you can configure this plugin on top of such an API by making the following request:

$ curl -X POST http://kong:8001/apis/{api}/plugins \
    --data "name=forward-proxy" 

  • api: either id or name of the API that this plugin configuration will target.

Global plugins

All plugins can be configured using the http://kong:8001/plugins/ endpoint. 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:

form parameterdefaultdescription
nameThe name of the plugin to use, in this case forward-proxy
service_idThe id of the Service which this plugin will target.
route_idThe id of the Route which this plugin will target.
enabledtrueWhether this plugin will be applied.
consumer_idThe id of the Consumer which this plugin will target.
api_idThe id of the API which this plugin will target. Note: The API Entity is deprecated in favor of Services since CE 0.13.0 and EE 0.32.
config.proxy_host

The hostname or IP address of the forward proxy to which to connect

config.proxy_port

The TCP port of the forward proxy to which to connect

config.proxy_scheme

http

The proxy scheme to use when connecting. Currently only http is supported

Notes

The plugin attempts to transparently replace upstream connections made by Kong core, sending the request instead to an intermediary forward proxy. Currently only transparent HTTP proxies are supported; TLS connections (via CONNECT) are not yet supported.