Request Transformer plugin

The Request Transformer plugin for Kong allows simple transformation of requests before they reach the upstream server. These transformations can be simple substitutions or complex ones matching portions of incoming requests using regular expressions, saving those matched strings into variables, and substituting those strings into transformed requests using flexible templates.

Configuration Reference

This plugin is compatible with requests with the following protocols:

http
https

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

Admin API

Kubernetes

Declarative (YAML)

Manager

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

curl -X POST http://{HOST}: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.replace.body=body-param1:new-value-1" \
    --data "config.replace.body=body-param2:new-value-2" \
    --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"

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: <request-transformer-example>
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
  replace:
    body:
    - body-param1:new-value-1
    - body-param2:new-value-2
  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
plugin: request-transformer

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: <request-transformer-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: 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
    replace:
      body:
      - body-param1:new-value-1
      - body-param2:new-value-2
    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.

Configure this plugin on a service:

In Kong Manager, select the workspace.
From the Dashboard, scroll down to Services and click View for the service row.
Scroll down to plugins and click Add Plugin.
Find and select the Request Transformer plugin.

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

Enable the plugin on a route

Admin API

Kubernetes

Declarative (YAML)

Manager

For example, configure this plugin on a route with:

$ curl -X POST http://{HOST}: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.replace.body=body-param1:new-value-1" \
    --data "config.replace.body=body-param2:new-value-2" \
    --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"

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: <request-transformer-example>
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
  replace:
    body:
    - body-param1:new-value-1
    - body-param2:new-value-2
  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
plugin: request-transformer

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: <request-transformer-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.

For example, 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
    replace:
      body:
      - body-param1:new-value-1
      - body-param2:new-value-2
    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.

Configure this plugin on a route:

In Kong Manager, select the workspace.
From the Dashboard, select Routes in the left navigation.
Click View for the route row.
Scroll down to plugins and click Add Plugin.
Find and select the Request Transformer plugin.

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

Enabling the plugin on a consumer

Admin API

Kubernetes

Declarative (YAML)

Manager

For example, configure this plugin on a consumer with:

$ curl -X POST http://{HOST}: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.replace.body=body-param1:new-value-1" \
    --data "config.replace.body=body-param2:new-value-2" \
    --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"

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:

apiVersion: configuration.konghq.com/v1
kind: KongPlugin
metadata:
  name: <request-transformer-example>
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
  replace:
    body:
    - body-param1:new-value-1
    - body-param2:new-value-2
  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
plugin: request-transformer

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

apiVersion: configuration.konghq.com/v1
kind: KongConsumer
metadata:
  name: {CONSUMER}
  annotations:
    konghq.com/plugins: <request-transformer-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:

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
    replace:
      body:
      - body-param1:new-value-1
      - body-param2:new-value-2
    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.

Configure this plugin on a consumer:

In Kong Manager, select the workspace.
From the Dashboard, scroll down to Consumers and click View for the consumer row.
Select the Plugins tab.
Click Add Plugin.
Find and select the Request Transformer plugin.

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

Admin API

Kubernetes

Declarative (YAML)

Kong Manager

For example, configure this plugin globally with:

$ curl -X POST http://{HOST}:8001/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.replace.body=body-param1:new-value-1" \
    --data "config.replace.body=body-param2:new-value-2" \
    --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"

Create a KongClusterPlugin resource and label it as global:

apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-request-transformer>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
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
  replace:
    body:
    - body-param1:new-value-1
    - body-param2:new-value-2
  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
plugin: request-transformer

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

plugins:
- name: request-transformer
  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
    replace:
      body:
      - body-param1:new-value-1
      - body-param2:new-value-2
    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

Configure this plugin globally:

In Kong Manager, select the workspace.
From the Dashboard, select Plugins in the left navigation.
Click New Plugin.
Find and select the Request Transformer plugin.

Note: If the plugin is greyed out, then it is not available for your product tier. See Kong Gateway tiers.
If the option is available, set the plugin scope to Global.
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`.
`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.
`config.http_method` optional Type: string	Sets the HTTP method for the upstream request.
`config.remove.headers` optional Type: array of string elements	List of header names. Unset the headers with the given name.
`config.remove.querystring` optional Type: array of string elements	List of querystring names. Remove the querystring if it is present.
`config.remove.body` optional Type: array of string elements	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 the parameter is present.
`config.replace.uri` optional Type: string	Updates the upstream request URI with a given value. This value can be used to update only the path part of the URI, not the scheme or the hostname.
`config.replace.body` optional Type: array of string elements	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.replace.headers` optional Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	List of `paramname: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 the parameter is present.
`config.replace.body` optional Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	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 the form-encoded body. Ignored if the parameter is already present.
`config.append.headers` optional Type: array of string elements	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 Type: array of string elements	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 Type: array of string elements	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, aggregate the two values (old and new) in an array.

Notes:

If the value contains a , (comma), 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.

Template as a Value

You can use any of the current request headers, query params, and captured URI groups as a template to populate the above supported configuration fields.

Request Param	Template
header	`$(headers.<header_name>)`, `$(headers["<Header-Name>"])` or `$(headers["<header-name>"])`)
querystring	`$(query_params.<query-param-name>)` or `$(query_params["<query-param-name>"])`)
captured URIs	`$(uri_captures.<group-name>)` or `$(uri_captures["<group-name>"])`)

To escape a template, wrap it inside quotes and pass it inside another template.
$('$(some_escaped_template)')

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

Advanced templates

The content of the placeholder $(...) is evaluated as a Lua expression, so logical operators may be used. For example:

Header-Name:$(uri_captures["user-id"] or query_params["user"] or "unknown")

This will first look for the path parameter (uri_captures). If not found, it will return the query parameter. If that also doesn’t exist, it returns the default value ‘“unknown”’.

Constant parts can be specified as part of the template outside the dynamic placeholders. For example, creating a basic-auth header from a query parameter called auth that only contains the base64-encoded part:

Authorization:Basic $(query_params["auth"])

Lambdas are also supported if wrapped as an expression like this:

$((function() ... implementation here ... end)())

A complete Lambda example for prefixing a header value with “Basic” if not already there:

Authorization:$((function()
    local value = headers.Authorization
    if not value then
      return
    end
    if value:sub(1, 6) == "Basic " then
      return value            -- was already properly formed
    end
    return "Basic " .. value  -- added proper prefix
  end)())

NOTE: Especially in multi-line templates like the example above, make sure not to add any trailing white space or new lines. Because these would be outside the placeholders, they would be considered part of the template, and hence would be appended to the generated value.

The environment is sandboxed, meaning that Lambdas will not have access to any library functions, except for the string methods (like sub() in the example above).

Examples Using Template as a Value

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

$ 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 plugin to add a new header x-consumer-id whose value is being set with the value sent with header x-user-id or with the default value alice. The header is missing.

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

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

The plugin adds a new header x-consumer-id with value alice before proxying request upstream.

Now try sending request with header x-user-id set:

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

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

Order of execution

Plugin performs the response transformation in the 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 the following examples, 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

Without 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"

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 a 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

Without 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"

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

Without 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"]}}}'

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
DB-less compatible?	Yes
Konnect tier
Konnect Cloud	Available
Version Compatibility
Kong Gateway (Enterprise) 2.4.x 2.3.x 2.2.x 2.1.x 1.5.x 1.3-x 0.36-x Kong Gateway (OSS) 2.4.x 2.3.x 2.2.x 2.1.x 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