alexbredy / gateway

Minimal API gateway

Objective

To serve as a low-fuss, minimal configuration reverse proxy for APIs. No complicated configurations, user portals, authentication, load balancing or anything. The point is that this can run behind something like Cloudflare that can take care of many of these concerns. Indeed, many API gateway solutions run behind load balancers or CDNs.

Minimal configuration:

{
  "port": "8080",
  "rules": {
    "/api": "localhost:8089"
  }
}

Full configuration:

{
  "version": "v1",
  "port": "8081",
  "rules": {
    "/users": "127.0.0.1:8089",
    "/products": "127.0.0.1:8088"
  },
  "not_found_error": {
     "code": 404,
     "domain": "Route not found",
     "message": "The requested route was not found"
  }
}

Getting started

You'll need to build the binary with go build. It's a static, standalone binary with no dependencies. The code can also be used as a Go library, and it has no dependencies outside the standard library.

Next, create a configuration file. The options are:

• version (Optional): This is a string that gets prefixed to URLs and ignored by backends e.g. a version string of v1 would lead the gateway to route /v1/users/asdf to /users/asdf.
• port (Optional): What port to run the gateway on. If this is not specified the HTTP_PLATFORM_PORT environment variable will be used.
• rules: A map of route prefix to backend. The backend will see the entire URL except for the version string, if that was specified. Rules are not applied in any particular order.
• not_found_error (Optional): Custom error object to return in case the request URL does not match any rules.

When you have created the configuration and built the gateway, just run it as

gateway path-to-config.json

Alternatively, you can set the path of the config file in an environment variable GATEWAY_CONFIG_FILE and run gateway without any additional arguments.