chroder/haproxy-lookup-backend repository overview

⁠About

This container runs an HAProxy instance with a custom Lua script that looks up the request domain against an API to decide which backend to use. The result can optionally be cached locally to improve subsequent requests.

• Source on Github: https://github.com/chroder/docker-haproxy-lookup-backend⁠
• Image on Docker Hub: https://hub.docker.com/r/chroder/haproxy-lookup-backend/~/settings/automated-builds/⁠
• Issues: https://github.com/chroder/docker-haproxy-lookup-backend/issues⁠

⁠Build

(1.) Create your own haproxy.cfg file. Use the default one as an example.

(2.) Create your own backend-lookup-config.lua file to define the lookup service. See below for info about the lookup service.

(3.) Build the container:

docker build -t haproxy-lookup-backend .

(4.) Run the container:

# http://localhost:4000/ -> haproxy port 80
docker run -p 4000:80 haproxy-lookup-backend

⁠Quick Run

You can mount the config files so you don't need to rebuild every time you run. Useful for testing.

docker run -p 4000:80 \
  -v `pwd`/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg \
  -v `pwd`/backend-lookup.lua:/usr/local/etc/haproxy/backend-lookup.lua \
  haproxy-lookup-backend

⁠Lookup Service

• MUST accept a query paramter named domain
• MUST return k=v pairs, one per line
• MUST return a backend_name key, which is the name of the backend to use
• MAY return any other key-value pairs. These will be added to the request as custom headers.

Example request:

Host: my-api.example.com
GET /lookup.txt?domain=foobar.com

Example response:

backend_name = php7_backend
x-custom-header = value
x-something-else = value