Request Transformer plugin

Transform the request sent by a client on the fly on Kong, before hitting the upstream server.

Note: The functionality of this plugin as bundled with versions of Kong prior to 0.10.0 differs from what is documented herein. Refer to the CHANGELOG for details.

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: an entity that makes requests for Kong to proxy; it represents either a user or an external service.
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

This plugin is compatible with requests with the following protocols:

http
https

This plugin is compatible with DB-less mode.

Enabling the plugin on a Service

With a database

Without 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-transformer"  \
    --data "config.remove.headers=x-toremove" \
    --data "config.remove.headers=x-another-one" \
    --data "config.remove.querystring=qs-old-name:qs-new-name" \
    --data "config.remove.querystring=qs2-old-name:qs2-new-name" \
    --data "config.remove.body=formparam-toremove" \
    --data "config.remove.body=formparam-another-one" \
    --data "config.rename.headers=header-old-name:header-new-name" \
    --data "config.rename.headers=another-old-name:another-new-name" \
    --data "config.rename.querystring=qs-old-name:qs-new-name" \
    --data "config.rename.querystring=qs2-old-name:qs2-new-name" \
    --data "config.rename.body=param-old:param-new" \
    --data "config.rename.body=param2-old:param2-new" \
    --data "config.add.headers=x-new-header:value" \
    --data "config.add.headers=x-another-header:something" \
    --data "config.add.querystring=new-param:some_value" \
    --data "config.add.querystring=another-param:some_value" \
    --data "config.add.body=new-form-param:some_value" \
    --data "config.add.body=another-form-param:some_value"

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

plugins:
- name: request-transformer
  service: {service}
  config: 
    remove.headers:
    - x-toremove
    - x-another-one
    remove.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    remove.body:
    - formparam-toremove
    - formparam-another-one
    rename.headers:
    - header-old-name:header-new-name
    - another-old-name:another-new-name
    rename.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    rename.body:
    - param-old:param-new
    - param2-old:param2-new
    add.headers:
    - x-new-header:value
    - x-another-header:something
    add.querystring:
    - new-param:some_value
    - another-param:some_value
    add.body:
    - new-form-param:some_value
    - another-form-param:some_value

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

Enabling the plugin on a Route

With a database

Without a database

Configure this plugin on a Route with:

$ curl -X POST http://kong:8001/routes/{route}/plugins \
    --data "name=request-transformer"  \
    --data "config.remove.headers=x-toremove" \
    --data "config.remove.headers=x-another-one" \
    --data "config.remove.querystring=qs-old-name:qs-new-name" \
    --data "config.remove.querystring=qs2-old-name:qs2-new-name" \
    --data "config.remove.body=formparam-toremove" \
    --data "config.remove.body=formparam-another-one" \
    --data "config.rename.headers=header-old-name:header-new-name" \
    --data "config.rename.headers=another-old-name:another-new-name" \
    --data "config.rename.querystring=qs-old-name:qs-new-name" \
    --data "config.rename.querystring=qs2-old-name:qs2-new-name" \
    --data "config.rename.body=param-old:param-new" \
    --data "config.rename.body=param2-old:param2-new" \
    --data "config.add.headers=x-new-header:value" \
    --data "config.add.headers=x-another-header:something" \
    --data "config.add.querystring=new-param:some_value" \
    --data "config.add.querystring=another-param:some_value" \
    --data "config.add.body=new-form-param:some_value" \
    --data "config.add.body=another-form-param:some_value"

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

plugins:
- name: request-transformer
  route: {route}
  config: 
    remove.headers:
    - x-toremove
    - x-another-one
    remove.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    remove.body:
    - formparam-toremove
    - formparam-another-one
    rename.headers:
    - header-old-name:header-new-name
    - another-old-name:another-new-name
    rename.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    rename.body:
    - param-old:param-new
    - param2-old:param2-new
    add.headers:
    - x-new-header:value
    - x-another-header:something
    add.querystring:
    - new-param:some_value
    - another-param:some_value
    add.body:
    - new-form-param:some_value
    - another-form-param:some_value

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

Enabling the plugin on a Consumer

With a database

Without a database

Configure this plugin on a Consumer with:

$ curl -X POST http://kong:8001/consumers/{consumer}/plugins \
    --data "name=request-transformer"  \
    --data "config.remove.headers=x-toremove" \
    --data "config.remove.headers=x-another-one" \
    --data "config.remove.querystring=qs-old-name:qs-new-name" \
    --data "config.remove.querystring=qs2-old-name:qs2-new-name" \
    --data "config.remove.body=formparam-toremove" \
    --data "config.remove.body=formparam-another-one" \
    --data "config.rename.headers=header-old-name:header-new-name" \
    --data "config.rename.headers=another-old-name:another-new-name" \
    --data "config.rename.querystring=qs-old-name:qs-new-name" \
    --data "config.rename.querystring=qs2-old-name:qs2-new-name" \
    --data "config.rename.body=param-old:param-new" \
    --data "config.rename.body=param2-old:param2-new" \
    --data "config.add.headers=x-new-header:value" \
    --data "config.add.headers=x-another-header:something" \
    --data "config.add.querystring=new-param:some_value" \
    --data "config.add.querystring=another-param:some_value" \
    --data "config.add.body=new-form-param:some_value" \
    --data "config.add.body=another-form-param:some_value"

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

plugins:
- name: request-transformer
  consumer: {consumer}
  config: 
    remove.headers:
    - x-toremove
    - x-another-one
    remove.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    remove.body:
    - formparam-toremove
    - formparam-another-one
    rename.headers:
    - header-old-name:header-new-name
    - another-old-name:another-new-name
    rename.querystring:
    - qs-old-name:qs-new-name
    - qs2-old-name:qs2-new-name
    rename.body:
    - param-old:param-new
    - param2-old:param2-new
    add.headers:
    - x-new-header:value
    - x-another-header:something
    add.querystring:
    - new-param:some_value
    - another-param:some_value
    add.body:
    - new-form-param:some_value
    - another-form-param:some_value

{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 further narrow the scope of the plugin.

Global plugins

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.

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.

Parameters

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

Form Parameter	Description
`name`	The name of the plugin to use, in this case `request-transformer`
`service.id`	The ID of the Service the plugin targets.
`route.id`	The ID of the Route the plugin targets.
`consumer.id`	The ID of the Consumer the plugin targets.
`enabled` default value: `true`	Whether this plugin will be applied.
`config.http_method` optional	Changes the HTTP method for the upstream request.
`config.remove.headers` optional	List of header names. Unset the header(s) with the given name.
`config.remove.querystring` optional	List of querystring names. Remove the querystring if it is present.
`config.remove.body` optional	List of parameter names. Remove the parameter if and only if content-type is one the following [`application/json`, `multipart/form-data`, `application/x-www-form-urlencoded`] and parameter is present.
`config.replace.headers` optional	List of headername:value pairs. If and only if the header is already set, replace its old value with the new one. Ignored if the header is not already set.
`config.replace.querystring` optional	List of queryname:value pairs. If and only if the field name is already set, replace its old value with the new one. Ignored if the field name is not already set.
`config.rename.headers` optional	List of headername:value pairs. If and only if the header is already set, rename the header. The value is unchanged. Ignored if the header is not already set.
`config.rename.querystring` optional	List of queryname:value pairs. If and only if the field name is already set, rename the field name. The value is unchanged. Ignored if the field name is not already set.
`config.rename.body` optional	List of parameter name:value pairs. Rename the parameter name if and only if content-type is one the following [`application/json`, `multipart/form-data`, `application/x-www-form-urlencoded`] and parameter is present.
`config.replace.body` optional	List of paramname:value pairs. If and only if content-type is one the following [`application/json`, `multipart/form-data`, `application/x-www-form-urlencoded`] and the parameter is already present, replace its old value with the new one. Ignored if the parameter is not already present.
`config.add.headers` optional	List of headername:value pairs. If and only if the header is not already set, set a new header with the given value. Ignored if the header is already set.
`config.add.querystring` optional	List of queryname:value pairs. If and only if the querystring is not already set, set a new querystring with the given value. Ignored if the header is already set.
`config.add.body` optional	List of pramname:value pairs. If and only if content-type is one the following [`application/json`, `multipart/form-data`, `application/x-www-form-urlencoded`] and the parameter is not present, add a new parameter with the given value to form-encoded body. Ignored if the parameter is already present.
`config.append.headers` optional	List of headername:value pairs. If the header is not set, set it with the given value. If it is already set, an additional new header with the same name and the new value will be appended.
`config.append.querystring` optional	List of queryname:value pairs. If the querystring is not set, set it with the given value. If it is already set, a new querystring with the same name and the new value will be set.
`config.append.body` optional	List of paramname:value pairs. If the content-type is one the following [`application/json`, `application/x-www-form-urlencoded`], add a new parameter with the given value if the parameter is not present, otherwise if it is already present, the two values (old and new) will be aggregated in an array.

Notes:

If the value contains a , then the comma-separated format for lists cannot be used. The array notation must be used instead.
The X-Forwarded-* fields are non-standard header fields written by Nginx to inform the upstream about client details and can’t be overwritten by this plugin. If you need to overwrite these header fields, see the post-function plugin in Serverless Functions.

Dynamic Transformation Based on Request Content

The Request Transformer plugin bundled with Kong Enterprise allows for adding or replacing content in the upstream request based on variable data found in the client request, such as request headers, query string parameters, or URI parameters as defined by a URI capture group.

If you already are a Kong Enterprise customer, you can request access to this plugin functionality by opening a support ticket using your Enterprise support channels.

If you are not a Kong Enterprise customer, you can inquire about our Enterprise offering by contacting us.

Order of execution

Plugin performs the response transformation in following order

remove –> rename –> replace –> add –> append

Examples

Kubernetes users: version v1beta1 of the Ingress specification does not allow the use of named regex capture groups in paths. If you use the ingress controller, you should use unnamed groups, e.g. (\w+)/ instead of (?<user_id>\w+). You can access these based on their order in the URL path, e.g. $(uri_captures[1]) will obtain the value of the first capture group.

In these examples we have the plugin enabled on a Service. This would work similarly for Routes.

Add multiple headers by passing each header:value pair separately:

With a database

$ curl -X POST http://localhost:8001/services/example-service/plugins \
  --data "name=request-transformer" \
  --data "config.add.headers[1]=h1:v1" \
  --data "config.add.headers[2]=h2:v1"

Without a database

plugins:
- name: request-transformer
  config:
    add:
      headers: ["h1:v1", "h2:v1"]

incoming request headers	upstream proxied headers:
h1: v1	h1: v1 h2: v1

Add multiple headers by passing comma separated header:value pair (only possible with a database):

$ curl -X POST http://localhost:8001/services/example-service/plugins \
  --data "name=request-transformer" \
  --data "config.add.headers=h1:v1,h2:v2"

incoming request headers	upstream proxied headers:
h1: v1	h1: v1 h2: v1

Add multiple headers passing config as JSON body (only possible with a database):

$ curl -X POST http://localhost:8001/services/example-service/plugins \
  --header 'content-type: application/json' \
  --data '{"name": "request-transformer", "config": {"add": {"headers": ["h1:v2", "h2:v1"]}}}'

incoming request headers	upstream proxied headers:
h1: v1	h1: v1 h2: v1

Add a querystring and a header:

With a database

$ curl -X POST http://localhost:8001/services/example-service/plugins \
  --data "name=request-transformer" \
  --data "config.add.querystring=q1:v2,q2:v1" \
  --data "config.add.headers=h1:v1"

Without a database

plugins:
- name: request-transformer
  config:
    add:
      headers: ["h1:v1"],
      querystring: ["q1:v1", "q2:v2"]

incoming request headers	upstream proxied headers:
h1: v2	h1: v2 h2: v1
h3: v1	h1: v1 h2: v1 h3: v1

incoming request querystring	upstream proxied querystring
?q1=v1	?q1=v1&q2=v1
	?q1=v2&q2=v1

Append multiple headers and remove a body parameter:

With a database

$ curl -X POST http://localhost:8001/services/example-service/plugins \
  --header 'content-type: application/json' \
  --data '{"name": "request-transformer", "config": {"append": {"headers": ["h1:v2", "h2:v1"]}, "remove": {"body": ["p1"]}}}'

Without a database

plugins:
- name: request-transformer
  config:
    add:
      headers: ["h1:v1", "h2:v1"]
    remove:
      body: [ "p1" ]

incoming request headers	upstream proxied headers:
h1: v1	h1: v1 h1: v2 h2: v1

incoming url encoded body	upstream proxied url encoded body:
p1=v1&p2=v1	p2=v1
p2=v1	p2=v1

About this Plugin
Made by
Categories	Transformations
Bundled with...
Kong Enterprise 1.5.x 1.3-x 0.36-x 0.35-x 0.34-x 0.33-x 0.32-x Kong Community 2.0.x 1.5.x 1.4.x 1.3.x 1.2.x 1.1.x 1.0.x 0.14.x 0.13.x 0.12.x 0.11.x 0.10.x 0.9.x 0.8.x 0.7.x 0.6.x 0.5.x 0.4.x 0.3.x