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Request Transformer Advanced

Kong Konnect only: This plugin is only available with a Kong Konnect subscription. Please inquire about Kong Konnect by contacting us.

The Request Transformer plugin for Kong Enterprise builds on the Kong version of this plugin with enhanced capabilities to match portions of incoming requests using regular expressions, save those matched strings into variables, and substitute those strings into transformed requests via flexible templates.

Configuration Reference

Enabling the plugin on a service

Admin API
Kubernetes
Declarative (YAML)
Manager

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

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$ curl -X POST http://<admin-hostname>:8001/services/<service>/plugins \
    --data "name=request-transformer-advanced"

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

First, create a KongPlugin resource:

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apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <request-transformer-advanced-example>
config:
  <optional_parameter>: <value>
plugin: request-transformer-advanced

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

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apiVersion: v1
kind: Service
metadata:
  name: <service>
  labels:
    app: <service>
  annotations:
    konghq.com/plugins: <request-transformer-advanced-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:

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plugins:
- name: request-transformer-advanced
  service: <service>
  config:
    <optional_parameter>: <value>

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

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 Request Transformer Advanced 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. Click Create.

Enabling the plugin on a route

Admin API
Kubernetes
Declarative (YAML)
Manager

For example, configure this plugin on a route with:

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$ curl -X POST http://<admin-hostname>:8001/routes/<route>/plugins \
    --data "name=request-transformer-advanced"

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

First, create a KongPlugin resource:

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apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <request-transformer-advanced-example>
config:
  <optional_parameter>: <value>
plugin: request-transformer-advanced

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

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apiVersion: networking/v1beta1
kind: Ingress
metadata:
  name: <route>
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: <request-transformer-advanced-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:

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plugins:
- name: request-transformer-advanced
  route: <route>
  config:
    <optional_parameter>: <value>

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

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 Request Transformer Advanced 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. Click Create.

Enabling the plugin on a consumer

Admin API
Kubernetes
Declarative (YAML)
Manager

For example, configure this plugin on a consumer with:

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$ curl -X POST http://<admin-hostname>:8001/consumers/<consumer>/plugins \
    --data "name=request-transformer-advanced"

<consumer> is the id or username of the consumer that this plugin configuration will target.

You can combine consumer.id, service.id, or route.id in the same request, to further narrow the scope of the plugin.

First, create a KongPlugin resource:

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apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <request-transformer-advanced-example>
config:
  <optional_parameter>: <value>
plugin: request-transformer-advanced

Then, apply it to a consumer by annotating the KongConsumer resource as follows:

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apiVersion: configuration.konghq.com/v1
kind: KongConsumer
metadata:
  name: <consumer>
  annotations:
    konghq.com/plugins: <request-transformer-advanced-example>
    kubernetes.io/ingress.class: kong

<consumer> is the id or username of the consumer 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 consumer by adding this section to your declarative configuration file:

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plugins:
- name: request-transformer-advanced
  consumer: <consumer>
  config:
    <optional_parameter>: <value>

<consumer> is the id or username of the consumer that this plugin configuration will target.

Configure this plugin on a consumer:

  1. In Kong Manager, select the workspace.
  2. From the Dashboard, scroll down to Consumers and click View for the consumer row.
  3. Select the Plugins tab.
  4. Click Add Plugin.

  5. Find and select the Request Transformer Advanced 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 Global.
  7. Click Create.

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.

Admin API
Kubernetes
Declarative (YAML)
Kong Manager

For example, configure this plugin globally with:

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$ curl -X POST http://<admin-hostname>:8001/plugins/ \
    --data "name=request-transformer-advanced"

Create a KongClusterPlugin resource and label it as global:

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apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-request-transformer-advanced>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
config:
  <optional_parameter>: <value>
plugin: request-transformer-advanced

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

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plugins:
- name: request-transformer-advanced
  config:
    <optional_parameter>: <value>

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 Request Transformer Advanced 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. Click Create.

Parameters

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

Form Parameter Description
name

Type: string		 The name of the plugin to use, in this case request-transformer-advanced.
service.id

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

Type: string		 The ID of the Route the plugin targets.
consumer.id

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

Type: boolean

Default value: true		 Whether this plugin will be applied.
api_id

Type: string		 The ID of the API the plugin targets.

Note: The API Entity is deprecated in favor of Services since CE 0.13.0 and EE 0.32.
config.http_method
optional

Changes the HTTP method for the upstream request
config.remove.headers
optional

List of header names. Unset the headers 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 querystring name is already set, replace its old value with the new one. Ignored if the header is not already set.
config.replace.uri
optional

Updates the upstream request URI with given value. This value can only be used to update the path part of the URI, not the scheme, nor the hostname.
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.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.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 name is not already set, set a new querystring with the given value. Ignored if the querystring name is already set.
config.add.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 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, a new header with the same name and the new value will be set.
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.

Note: if the value contains a , then the comma separated format cannot be used. The array notation must be used instead.

Template as Value

User can use any of the the current request headers, query params, and captured URI named groups as template to populate above supported config fields.

Request Param Template
header $(headers. or $(headers['']) or 'optional_default')
querystring $(query_params. or $(query_params['query-param-name']) or 'optional_default')
captured URIs $(uri_captures. or $(uri_captures['group-name']) or 'optional_default')

To escape a template, wrap it inside quotes and pass inside another template.
Ex. $(‘$(some_needs_to_escaped)’)

Note: Plugin creates a non mutable table of request headers, querystrings, and captured URIs before transformation. So any update or removal of params used in template does not affect the rendered value of template.

Examples Using Template as Value

Add an API test with uris configured with a named capture group user_id

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$ curl -X POST http://localhost:8001/apis \
    --data 'name=test' \
    --data 'upstream_url=http://mockbin.com' \
    --data-urlencode 'uris=/requests/user/(?<user_id>\w+)' \
    --data "strip_uri=false"

Enable the ‘request-transformer-advanced’ plugin to add a new header x-consumer-id and its value is being set with the value sent with header x-user-id or with the default value alice is header is missing.

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$ curl -X POST http://localhost:8001/apis/test/plugins \
    --data "name=request-transformer-advanced" \
    --data-urlencode "config.add.headers=x-consumer-id:\$(headers['x-user-id'] or 'alice')" \
    --data "config.remove.headers=x-user-id"

Now send a request without setting header x-user-id

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$ curl -i -X GET localhost:8000/requests/user/foo

Plugin will add a new header x-consumer-id with value alice before proxying request upstream. Now try sending request with header x-user-id set

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$ curl -i -X GET localhost:8000/requests/user/foo \
  -H "X-User-Id:bob"

This time plugin will add a new header x-consumer-id with value sent along with header x-user-id, i.e.bob

Order of Execution

Plugin performs the response transformation in following order

remove –> replace –> add –> append

Configuration Examples

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

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$ curl -X POST http://localhost:8001/apis/mockbin/plugins \
  --data "name=request-transformer-advanced" \
  --data "config.add.headers[1]=h1:v1" \
  --data "config.add.headers[2]=h2:v1"
Incoming Request Headers Upstream Proxied Headers
h1: v1 h1: v1, h2: v1

Add multiple headers by passing comma separated header:value pair:

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$ curl -X POST http://localhost:8001/apis/mockbin/plugins \
  --data "name=request-transformer-advanced" \
  --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:

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$ curl -X POST http://localhost:8001/apis/mockbin/plugins \
  --header 'content-type: application/json' \
  --data '{"name": "request-transformer-advanced", "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:

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$ curl -X POST http://localhost:8001/apis/mockbin/plugins \
  --data "name=request-transformer-advanced" \
  --data "config.add.querystring=q1:v2,q2=v1" \
  --data "config.add.headers=h1:v1"
Incoming Request Headers Upstream Proxied Headers
h1: v1 h1: v1, 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:

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

Add multiple headers and querystring parameters if not already set:

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$ curl -X POST http://localhost:8001/apis/mockbin/plugins \
  --data "name=request-transformer-advanced" \
  --data "config.add.headers=h1:v1,h2:v1" \
  --data "config.add.querystring=q1:v2,q2:v1" \
Incoming Request Headers Upstream Proxied Headers
h1: v1 h1: v1, 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
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