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Reedelk Transformer

The Reedelk Transformer plugin transforms the upstream request body or downstream response body by invoking a Reedelk REST flow before hitting the upstream server, or before sending the downstream response back to the client. The plugin can apply both upstream and downstream transformations in the same flow.

Installation

Prerequisites

To use the Reedelk plugin for Kong, you must first install the Reedelk IntelliJ IDEA flow designer plugin using either of the following options:

  • IntelliJ Marketplace: Go to IntelliJ Preferences > Plugin > Marketplace, search for Reedelk, install the plugin, and restart IntelliJ.

  • Manual install: From IntelliJ Preferences > Plugin > Settings icon > Install Plugin From Disk, and restart IntelliJ.

Install the Reedelk Transformer plugin

  1. Clone the kong-plugin-reedelk-transformer:

     $ git clone https://github.com/reedelk/kong-plugin-reedelk-transformer.git
 $ cd kong-plugin-reedelk-transformer

  2. Install the module kong-plugin-reedelk-transformer:

    $ luarocks install kong-plugin-reedelk-transformer-0.1.0-1.all.rock

  3. Add the custom plugin to kong.conf:

    plugins = ...,reedelk-transformer

  4. Restart Kong.

    $ kong restart

Build and package the plugin

  1. Install the LuaRocks package manager.

  2. Clone the kong-plugin-reedelk-transformer:

     $ git clone https://github.com/reedelk/kong-plugin-reedelk-transformer.git
 $ cd kong-plugin-reedelk-transformer

  3. Build the plugin locally (based on the .rockspec in the current directory):

    $ luarocks make

  4. Package the plugin:

    $ luarocks pack kong-plugin-reedelk-transformer 0.1.0-1

Hello World Example

This example uses a prepackaged kong-reedelk Docker image with Kong and the reedelk-transformer plugin already installed. You can find the kong-reedelk Docker images on Docker Hub.

The kong-reedelk image is preconfigured to use the following kong.yml file, which defines an upstream service mapped on Route http://localhost:8000/transform and invokes a downstream transformer with the reedelk-transformer plugin. The configured downstream transformer integration flow URL is:

http://host.docker.internal:8282/api/message

Prerequisites

Run the example

In the following steps, you run the kong-reedelk docker image, and then create a new Reedelk project that contains the integration flow invoked by the downstream transformer.

  1. Run the kong-reedelk Docker image:

    $ docker run -d --name kong-reedelk-transformer-plugin \
         -p 8000:8000 \
         -p 8443:8443 \
         -p 127.0.0.1:8001:8001 \
         -p 127.0.0.1:8444:8444 \
         reedelk/kong-reedelk-transformer-plugin:latest

  2. Make sure that Kong is up and running correctly with the reedelk-transformer plugin installed:

    $ curl http://localhost:8001/plugins

  3. Open IntelliJ and create a new Reedelk project. The newly created project contains a POST Hello World flow to use as integration flow invoked by the downstream transformer.

  4. Start the new Reedelk project by clicking Play next to the Reedelk Runtime run configuration in IntelliJ.

    Reedelk Runtime

  5. Call the Kong Route with the following URL:

    $ http://localhost:8000/transform

    The result should be:

    Hello World John

For more information about this example, including testing the IntelliJ Flow Designer Plugin workflow with Insomnia, see:

Configuration Reference

This plugin is compatible with DB-less mode.

Example plugin configuration

The following examples provide some typical configurations for enabling the reedelk-transformer plugin on a service.

Make the following request:

curl -X POST http://localhost:8001/services/SERVICE_NAME|SERVICE_ID/plugins \
    --data "name=reedelk-transformer"  \
    --data "config.upstream_transformer_url=http://myhost/upstream/transform" \
    --data "config.downstream_transformer_url=http://myhost/downstream/transform"

Replace SERVICE_NAME|SERVICE_ID with 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: reedelk-transformer-example
config: 
  upstream_transformer_url: http://myhost/upstream/transform
  downstream_transformer_url: http://myhost/downstream/transform
plugin: reedelk-transformer

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

apiVersion: v1
kind: Service
metadata:
  name: SERVICE_NAME|SERVICE_ID
  labels:
    app: SERVICE_NAME|SERVICE_ID
  annotations:
    konghq.com/plugins: reedelk-transformer-example
spec:
  ports:
  - port: 80
    targetPort: 80
    protocol: TCP
    name: SERVICE_NAME|SERVICE_ID
  selector:
    app: SERVICE_NAME|SERVICE_ID

Replace SERVICE_NAME|SERVICE_ID with 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.

Add this section to your declarative configuration file:

plugins:
- name: reedelk-transformer
  service: SERVICE_NAME|SERVICE_ID
  config: 
    upstream_transformer_url: http://myhost/upstream/transform
    downstream_transformer_url: http://myhost/downstream/transform

Replace SERVICE_NAME|SERVICE_ID with the id or name of the service that this plugin configuration will target.

The following examples provide some typical configurations for enabling the reedelk-transformer plugin on a route.

Make the following request:

curl -X POST http://localhost:8001/routes/ROUTE_NAME|ROUTE_ID/plugins \
  --data "name=reedelk-transformer"  \
    --data "config.upstream_transformer_url=http://myhost/upstream/transform" \
    --data "config.downstream_transformer_url=http://myhost/downstream/transform"

Replace ROUTE_NAME|ROUTE_ID with 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: reedelk-transformer-example
config: 
  upstream_transformer_url: http://myhost/upstream/transform
  downstream_transformer_url: http://myhost/downstream/transform
plugin: reedelk-transformer

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

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ROUTE_NAME|ROUTE_ID
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: reedelk-transformer-example
spec:
  rules:
  - host: examplehostname.com
    http:
      paths:
      - path: /bar
        backend:
          service:
            name: echo
            port:
              number: 80

Replace ROUTE_NAME|ROUTE_ID with 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.

Add this section to your declarative configuration file:

plugins:
- name: reedelk-transformer
  route: ROUTE_NAME
  config: 
    upstream_transformer_url: http://myhost/upstream/transform
    downstream_transformer_url: http://myhost/downstream/transform

Replace ROUTE_NAME|ROUTE_ID with the id or name of the route that this plugin configuration will target.

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.

The following examples provide some typical configurations for enabling the reedelk-transformer plugin globally.

Make the following request:

curl -X POST http://localhost:8001/plugins/ \
  --data "name=reedelk-transformer"  \
    --data "config.upstream_transformer_url=http://myhost/upstream/transform" \
    --data "config.downstream_transformer_url=http://myhost/downstream/transform"

Create a KongClusterPlugin resource and label it as global:

apiVersion: configuration.konghq.com/v1
kind: KongClusterPlugin
metadata:
  name: <global-reedelk-transformer>
  annotations:
    kubernetes.io/ingress.class: kong
  labels:
    global: \"true\"
config: 
  upstream_transformer_url: http://myhost/upstream/transform
  downstream_transformer_url: http://myhost/downstream/transform
plugin: reedelk-transformer

Add a plugins entry in the declarative configuration file:

plugins:
- name: reedelk-transformer
  config: 
    upstream_transformer_url: http://myhost/upstream/transform
    downstream_transformer_url: http://myhost/downstream/transform

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 reedelk-transformer.
service.name or service.id

Type: string		 The name or ID of the service the plugin targets.

Set one of these parameters if adding the plugin to a service through the top-level /plugins endpoint.

Not required if using /services/SERVICE_NAME|SERVICE_ID/plugins.
route.name or route.id

Type: string		 The name or ID of the route the plugin targets.

Set one of these parameters if adding the plugin to a route through the top-level /plugins endpoint.

Not required if using /routes/ROUTE_NAME|ROUTE_ID/plugins.
enabled

Type: boolean

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

The URL of the Reedelk REST flow endpoint to invoke for the upstream request transformation.
config.downstream_transformer_url
optional

The URL of the Reedelk REST flow endpoint to invoke for the downstream request transformation.

The upstream_transformer_url and downstream_transformer_url are the URLs of the Reedelk REST flow endpoint to invoke for the upstream/downstream request/response transformations; e.g., http://localhost:8888/apiabledev/transform.