Traefik Plugin: Response Rewrite Body

This repo contains a Traefik plugin that allows you to rewrite response body based on a parameters.

Configuration

It is possible to install the plugin locally or to install it through Traefik Pilot.

Configuration as local plugin

Depending on your setup, the installation steps might differ from the one described here. This example assumes that your Traefik instance runs in a Docker container and uses the official image.

Download the latest release of the plugin and save it to a location the Traefik container can reach. Below is an example of a possible setup. Notice how the plugin source is mapped into the container (/plugin/traefik-responsebodyrewrite:/plugins-local/src/github.com/quortex/traefik-responsebodyrewrite/) via a volume bind mount:

docker-compose.yml

version: "3.7"

services:
  traefik:
    image: traefik

    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /docker/config/traefik/traefik.yml:/etc/traefik/traefik.yml
      - /docker/config/traefik/dynamic-configuration.yml:/etc/traefik/dynamic-configuration.yml
      - /docker/config/traefik/plugin/traefik-responsebodyrewrite:/plugins-local/src/github.com/quortex/traefik-responsebodyrewrite/

    ports:
      - "8080:80"

  hello:
    image: ealen/echo-server
    labels:
      - traefik.enable=true
      - traefik.http.routers.hello.entrypoints=http
      - traefik.http.routers.hello.rule=Host(`localhost`)
      - traefik.http.services.hello.loadbalancer.server.port=80
      - traefik.http.routers.hello.middlewares=my-traefik-responsebodyrewrite@file
      

To complete the setup, the Traefik configuration must be extended with the plugins. For this you must create the traefik.yml and the dynamic-configuration.yml` files if not present already.

log:
  level: INFO

experimental:
  localPlugins:
    traefik-responsebodyrewrite:
      moduleName: github.com/quortex/traefik-responsebodyrewrite

dynamic-configuration.yml

http:
  middlewares:
    my-traefik-responsebodyrewrite:
      plugin:
        traefik-responsebodyrewrite:
          responses:
            - status: 200
              rewrites:
                - regex: foo
                  replacement: "Bar"
            - status: 400-499
              rewrites:
                - regex: .*
                  replacement: "Error Replacement"

 

Traefik Plugin registry

This procedure will install the plugins via the Traefik Plugin registry.

Add the following code to your traefik-config.yml

experimental:
  plugins:
    traefik-responsebodyrewrite:
      moduleName: "github.com/quortex/traefik-responsebodyrewrite"
      version: "v0.0.0"
# other stuff you might have in your traefik-config
entryPoints:
  http:
    address: ":80"
  https:
    address: ":443"

providers:
  docker:
    endpoint: "unix:///var/run/docker.sock"
    exposedByDefault: false
  file:
    filename: "/etc/traefik/dynamic-configuration.yml"

In your dynamic configuration add the following code:

http:
  middlewares:
    my-traefik-responsebodyrewrite:
      plugin:
        traefik-responsebodyrewrite:
          responses:
            - status: 200
              rewrites:
                - regex: foo
                  replacement: "Bar"
            - status: 400-499
              rewrites:
                - regex: .*
                  replacement: "Error Replacement"

Develop

A docker compose configuration is already sets to run a traefik and and echo server with local plugin deployed

docker compose -f docker/dev/docker-compose.yml up

Testing body rewrite

You can run a curl to check the response body

curl  -v "http://localhost:8080?echo_body=foobrady&echo_code=200"
curl  -v "http://localhost:8080?echo_body=foobrady&echo_code=404"
curl  -v "http://localhost:8080?echo_body=foobrady&echo_code=500"

• 200 should return Barbrady
• 404 should return Error Replacement
• 500 should not be modified and return barbrady