Traefik HTTP Merge

A lightweight Go-based HTTP proxy and merger for combining two Traefik dynamic configuration providers into a single API endpoint. The primary provider is treated as read-only (its data takes precedence in merges), while the secondary supports read/write operations.

This tool acts as a shim: for GET requests, it fetches and deeply merges configurations from both providers (primary overrides secondary on conflicts). For non-GET methods (e.g., POST, PUT, DELETE), it proxies requests directly to the secondary provider for writes.

Ideal for scenarios where you have a read-only Traefik config source (e.g., from a monitoring service) and a writable one (e.g., from an admin dashboard), and you want a unified API for Traefik's dynamic configuration.

Features

• Deep JSON Merge: Recursively merges nested objects and appends arrays from both providers.
• Read-Only Primary: Primary endpoint data is fetched on reads but never modified.
• Read/Write Secondary: All writes are proxied to the secondary endpoint.
• Configurable via Env Vars: Easy setup with Docker or bare Go.
• Lightweight: Single static binary, no external dependencies (standard library only).
• Timeout Handling: Configurable HTTP client timeouts for reliability.
• Docker Multi-Arch Support: Builds for amd64; extendable for arm64.

Quick Start

Using Docker

Pull the latest image:

docker pull hhftechnology/traefik-http-merge:latest

Run with environment variables for your endpoints:

docker run -d \
  --name traefik-merge \
  -p 9000:9000 \
  -e MERGE_ENDPOINTS="http://primary:8080/api/traefik,http://secondary:8080/api/traefik" \
  -e MERGE_LISTEN=":9000" \
  hhftechnology/traefik-http-merge:latest

• MERGE_ENDPOINTS: Comma-separated list (first=primary/read-only, second=secondary/read-write).
• MERGE_LISTEN: Bind address (default :9000).

Your unified API will be available at http://localhost:9000/traefik-merged.

Using Docker Compose

Example docker-compose.yml (adapt to your network):

services:
  traefik-merge:
    image: hhftechnology/traefik-http-merge:latest
    container_name: traefik-merge
    restart: unless-stopped
    ports:
      - "9000:9000"
    environment:
      # Primary (read-only) first, secondary (read-write) second
      MERGE_ENDPOINTS: >
        http://pangolin:3001/api/v1/traefik-config,
        http://middleware-manager:80/traefik-config
      MERGE_LISTEN: ":9000"
    networks:
      - pangolin

networks:
  pangolin:
    external: true

Run with docker-compose up -d.

API Usage

The proxy exposes a single endpoint: /traefik-merged.

GET /traefik-merged

• Purpose: Fetch merged configuration.
• Response: JSON object merging both providers (primary overrides secondary).
• Example:

  curl http://localhost:9000/traefik-merged

  Response:

  {
    "http": {
      "routers": {
        // Merged routers from both (primary wins on key conflicts)
      },
      "services": {
        // Merged services
      }
    }
  }

Non-GET Methods (POST, PUT, DELETE, etc.)

• Purpose: Modify secondary provider only.
• Behavior: Proxied transparently to secondary (body, headers, method preserved).
• Example (adding a router):

  curl -X POST http://localhost:9000/traefik-merged \
    -H "Content-Type: application/json" \
    -d '{
      "http": {
        "routers": {
          "my-router": {
            "rule": "Host(`example.com`)"
          }
        }
      }
    }'

Configuration

Env Var	Description	Default	Example
MERGE_ENDPOINTS	Comma-separated URLs: primary (read-only), secondary (read-write). Required.	N/A	http://primary:8080/traefik.json,http://secondary:8080/traefik.json
MERGE_LISTEN	HTTP listen address.	:9000	:8080

Building from Source

Prerequisites

• Go 1.23+
• Docker (for image build)

Go Build

git clone https://github.com/hhftechnology/traefik-http-merge.git
cd traefik-http-merge
go mod download
go build -ldflags="-s -w" -o traefik-merge traefik-merge.go
./traefik-merge

Docker Build

docker build -t traefik-http-merge .
docker run -p 9000:9000 traefik-http-merge

Contributing

1. Fork the repo.
2. Create a feature branch (git checkout -b feature/my-feature).
3. Commit changes (git commit -m 'Add my feature').
4. Push to branch (git push origin feature/my-feature).
5. Open a Pull Request.

Report issues or suggest improvements via GitHub Issues.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Built with Go standard library.
• Inspired by Traefik's dynamic configuration needs.