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Introduction

Baker is a dynamic HTTP reverse proxy with a focus on extensibility and flexibility. It is designed to adapt to a variety of orchestration engines and provides dynamic configuration capabilities, eliminating the need to restart the reverse proxy when changing configurations.

Features

Feature	Description
🐳 Docker Integration	Native Docker driver for real-time container event listening
🔌 Pluggable Drivers	Exposed driver interface for easy integration with other orchestration engines
⚡ Dynamic Config	Hot-reload configuration without restarts
🌳 Fast Routing	Custom trie data structure for high-performance path pattern matching
📚 Library Mode	Use as a library—implements the standard http.Handler interface
🔧 Extensible	Exposed interfaces for most components
🔀 Middleware	Modify incoming and outgoing traffic with built-in or custom middleware
⚖️ Load Balancing	Built-in load balancing across service instances
🔒 Auto SSL	Automatic certificate creation and renewal via Let's Encrypt
🚦 Rate Limiting	Configurable rate limiter per domain and path
📊 Metrics	Prometheus metrics available at /metrics endpoint
📋 Static Config	Support for services without dynamic configuration endpoints
🔄 WebSocket	Full WebSocket proxy support

Quick Start

1. Deploy Baker

Create a docker-compose.yml for Baker:

services:
  baker:
    image: ellato/baker:latest
    environment:
      - BAKER_ACME=NO              # Enable/disable ACME (Let's Encrypt)
      - BAKER_ACME_PATH=/acme/cert # Certificate storage path
      - BAKER_LOG_LEVEL=DEBUG      # Log level: DEBUG, INFO, WARN, ERROR
      - BAKER_BUFFER_SIZE=100      # Event buffer size
      - BAKER_PING_DURATION=2s     # Health check interval
      - BAKER_METRICS_ADDR=:8089   # Metrics endpoint address
    ports:
      - "80:80"
      - "443:443"
    networks:
      - baker
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - ./acme/cert:/acme/cert

networks:
  baker:
    name: baker
    driver: bridge

2. Configure Your Service

Add Baker labels to your service's docker-compose.yml:

services:
  my-service:
    image: my-service:latest
    labels:
      - "baker.enable=true"
      - "baker.network=baker"
      - "baker.service.port=8000"
      - "baker.service.ping=/config"
      # Optional: Static configuration (for non-dynamic services)
      - "baker.service.static.domain=api.example.com"
      - "baker.service.static.path=/*"
      - "baker.service.static.headers.host=api.example.com"
    networks:
      - baker

networks:
  baker:
    name: baker
    external: true

Note: Ensure both Baker and your service share the same Docker network.

Configuration

Environment Variables

Variable	Default	Description
BAKER_ACME	NO	Enable Let's Encrypt automatic SSL
BAKER_ACME_PATH	/acme/cert	Directory for SSL certificates
BAKER_LOG_LEVEL	INFO	Logging level
BAKER_BUFFER_SIZE	100	Docker event buffer size
BAKER_PING_DURATION	2s	Service health check interval
BAKER_METRICS_ADDR	:8089	Prometheus metrics endpoint

Service Labels

Label	Required	Description
baker.enable	Yes	Enable Baker for this container
baker.network	Yes	Docker network name
baker.service.port	Yes	Service port to proxy to
baker.service.ping	Yes	Health check / config endpoint
baker.service.static.domain	No	Static domain (bypasses dynamic config)
baker.service.static.path	No	Static path pattern
baker.service.static.headers.*	No	Custom headers to add

Dynamic Configuration Endpoint

Your service should expose a REST endpoint (specified by baker.service.ping) that returns routing configuration:

[
  {
    "domain": "example.com",
    "path": "/api/v1",
    "ready": true
  },
  {
    "domain": "example.com",
    "path": "/api/v2",
    "ready": false
  },
  {
    "domain": "app.example.com",
    "path": "/app/*",
    "ready": true,
    "rules": [
      {
        "type": "ReplacePath",
        "args": {
          "search": "/app",
          "replace": "",
          "times": 1
        }
      }
    ]
  }
]

Field	Type	Description
domain	string	Domain to match
path	string	Path pattern (supports * wildcard)
ready	boolean	Whether the route is active
rules	array	Optional middleware rules

Middleware

Baker includes several built-in middleware for request/response modification:

ReplacePath

Replaces or removes parts of the request path before forwarding to the backend service.

{
  "type": "ReplacePath",
  "args": {
    "search": "/api/v1",
    "replace": "",
    "times": 1
  }
}

Argument	Type	Description
search	string	Pattern to search for
replace	string	Replacement string
times	integer	Number of replacements (-1 for all)

Example: Request to /api/v1/users → Backend receives /users

---

AppendPath

Adds prefixes and/or suffixes to the request path.

{
  "type": "AppendPath",
  "args": {
    "begin": "/v2",
    "end": ".json"
  }
}

Argument	Type	Description
begin	string	Prefix to add
end	string	Suffix to add

Example: Request to /users → Backend receives /v2/users.json

---

RateLimiter

Applies rate limiting per client IP address.

{
  "type": "RateLimiter",
  "args": {
    "request_limit": 100,
    "window_duration": "60s"
  }
}

Argument	Type	Description
request_limit	integer	Maximum requests per window
window_duration	string	Time window (e.g., 60s, 1m, 1h)

When the limit is exceeded, clients receive a 429 Too Many Requests response.

License

Baker is licensed under the MIT LICENSE.