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:

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

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

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

3. Add the custom plugin to kong.conf:

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   plugins = ...,reedelk-transformer
   

4. Restart Kong.

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   $ kong restart
   

Build and package the plugin

1. Install the LuaRocks package manager.

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

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    $ 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):

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   $ luarocks make
   

4. Package the plugin:

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   $ 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:

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

Prerequisites

• Docker must be installed.
• IntelliJ IDEA IDE must be installed.
• Reedelk IntelliJ Flow Designer Plugin must be installed on your IntelliJ distribution.

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:

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   $ 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:

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   $ 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.

   

5. Call the Kong Route with the following URL:

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   $ 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:

• Reedelk Getting Started documentation.
• Reedelk plugin documentation on GitHub.
• Kong Reedelk Transformer Plugin Demo video on Youtube.

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

Enabling the plugin on a service

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$ curl -X POST http://<admin-hostname>:8001/services/<service>/plugins \
    --data "name=reedelk-transformer"  \
    --data "config.upstream_transformer_url=http://myhost/upstream/transform" \
    --data "config.downstream_transformer_url=http://myhost/downstream/transform"

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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

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

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

Enabling the plugin on a route

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$ curl -X POST http://<admin-hostname>:8001/routes/<route>/plugins \
    --data "name=reedelk-transformer"  \
    --data "config.upstream_transformer_url=http://myhost/upstream/transform" \
    --data "config.downstream_transformer_url=http://myhost/downstream/transform"

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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

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apiVersion: networking/v1beta1
kind: Ingress
metadata:
  name: <route>
  annotations:
    kubernetes.io/ingress.class: kong
    konghq.com/plugins: <reedelk-transformer-example>
spec:
  rules:
  - host: examplehostname.com
    http:
      paths:
      - path: /bar
        backend:
          serviceName: echo
          servicePort: 80

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

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.

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

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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

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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:

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.