client

KrakenD - HTTP Client Plugin Example

This repository provides an example of how to build and inject a Client Plugin into the KrakenD API Gateway. Follow the steps below to understand how to set up and use the client plugin.

Overview

The client plugin, named my-client-plugin, demonstrates how to create a custom HTTP client that can be integrated into KrakenD. The plugin replaces the default HTTP client by adding custom logic before and after the request is processed.

File Structure

• client.go: The main plugin code that implements the RegisterClient interface.
• go.mod: The Go module file.
• Makefile: Instructions for building the plugin using Docker.

Prerequisites

• Go
• Docker
• KrakenD API Gateway (version 2.x)

Building the Plugin

You should build the plugin using the KrakenD Docker builder image. The Makefile includes targets for different architectures.

Steps

1. Clone the Repository:

   git clone https://github.com/krakend/examples.git
   cd examples/plugins/client

2. Build for Different Architectures:

   • For amd64:

     make amd64

   • For arm64:

     make arm64

   • For linux_amd64 (non-docker):

     make linux_amd64

   • For linux_arm64 (non-docker):

     make linux_arm64

Plugin Configuration

To use the plugin in your KrakenD configuration, add it under the extra_config section of your krakend.json file.

Example Configuration

{
  "version": 3,
  "plugin": {
    "pattern": ".so",
    "folder": "/etc/krakend/plugins"
  },
  "host": ["http://localhost:8080/"],
  "debug_endpoint": true,
  "endpoints": [
    {
      "endpoint": "/example",
      "backend": [
        {
          "url_pattern": "/__debug/",
          "extra_config": {
            "plugin/http-client": {
              "name": "my-client-plugin",
              "my-client-plugin": {
                "option": "/some-path"
              }
            }
          }
        }
      ]
    }
  ]
}

Logger Interface

The plugin supports a logger interface to help with debugging and logging messages.

Logger Methods

• Debug(v ...interface{})
• Info(v ...interface{})
• Warning(v ...interface{})
• Error(v ...interface{})
• Critical(v ...interface{})
• Fatal(v ...interface{})

Custom Logic

The my-client-plugin adds custom logic by wrapping the default HTTP client. It logs the request details and copies headers, status codes, and body from the backend response to the client response.

Usage

1. Build the plugin using the appropriate make target. The plugin will be generated under the plugins folder.
2. Test your KrakenD using Docker, for instance:

docker run --rm -it --name krakend -p 8080:8080 -v "$PWD:/etc/krakend" devopsfaith/krakend

3. Send an example call

curl -iG 'http://localhost:8080/example'

For more details on client plugins and extending KrakenD, refer to the official documentation.