Limitr

A HTTP/HTTPS request rate limiter written in Go.

About Limitr

Limitr works by forwarding requests to a specified URL and moderating the rate at which requests can be made in accordance with a defined number of requests per defined time window. If the rate limit is exceeded, the server will respond with a 429 Too Many Requests status code.

Why did I write Limitr?

I had a need for rate limiting a self-hosted API that I was developing, and couldn't find any standalone rate limiters that weren't part of some API gateway or reverse proxy. I wanted something that I could run on my server and configure to my liking.

Technologies used

• Go: The server is written in Go
• Go Fiber: The server uses Go Fiber to handle HTTP requests
• Redis: The rate limiter uses Redis to store rate limit data
• Docker: The server can be run in a Docker container

Why Go and Why Redis?

I chose Go primarily for its speed. Since the server is a rate limiter, it needs to be able to handle requests quickly. I chose Redis for the same reason. Redis is an in-memory database that is very fast and can handle a large number of requests.

Getting Started

Prerequisites

Environment Variables

You can set the following environment variables to configure the rate limiter:

• FORWARD_URL (required): The URL to forward requests to
• RATE_LIMIT (required): The number of requests allowed per time window
• TIME_WINDOW (required): The time window in seconds
• PORT (optional, default: 7654): The port the server will listen on
• USE_TLS (optional, default: false): If true, use TLS (certificates are required)
• IP_HEADER_KEY (optional, default: blank): The header key that contains the client's IP address
• REDIS_ADDR (optional, default: localhost:6379): The address where the Redis server is running
• REDIS_PASSWORD (optional, default: ""): The password of the Redis server. Please set a new password here and in redisconfig/redis.conf if you are using Redis in a production environment
• REDIS_DB (optional, default: 0): The database of the Redis server
• VERBOSE_MODE (optional, default: false): If true, prints incoming requests to the console
• SYSLOG_ENABLED (optional, default: false): If true, sends logs of incoming requests to a syslog server
• SYSLOG_HOST (required if SYSLOG_ENABLED is true): The address of the syslog server
• SYSLOG_PORT (required if SYSLOG_ENABLED is true): The port of the syslog server

You can store these variables in a .env file in the same directory as the executable. If there is no .env file, the server will check to see if the variables are otherwise set. Variables stored in .env will take precedence over those already set in the environment before running.

If you are using docker compose, you will need to set these variables in the docker-compose.yml file.

Redis

The rate limiter uses Redis to store the rate limit data.

The docker-compose.yml file in the root of the project contains a Redis service. If you are not using docker compose you will need to set up a Redis server yourself. Make sure to set your environment variables appropriately (see the environment variables section).

Some Quick Info

The master branch contains the latest stable release. Active development is done in the dev branch.

Running Limitr Normally

Using Docker

The easiest way to use Limitr in Docker is via Docker Compose.

First, clone this repository:

git clone https://github.com/BeehiveBroadband/limitr.git
cd limitr

To run the server using Docker Compose, you can use the following command from within the project directory root:

docker-compose up

This will start the Limitr server and a Redis server. The server will be available at http://localhost:7654.

Note: When running in Docker, Limitr cannot accurately get the client's IP address from the request. You will need to run the container behind a reverse proxy (such as Nginx, HAProxy, Cloudflare Tunnels, etc.) that can forward the client IP address in a header. You will then need to set the IP_HEADER_KEY environment variable to the header key that contains the client's IP address. Alternatively, you can run Limitr without Docker, or you can modify docker-compose.yml to run both containers in host network mode (only available on Linux hosts), both of which will allow you to get the client's IP address directly from the request. If you choose one of these options, please make sure to secure your Redis server accordingly.

Limitr is also available in a docker image that you can obtain by running:

docker pull beehivenetops/limitr

Using the executable

You can download the executable on the releases page. Download the appropriate release for your system and run the executable.

./[executable name]

Note: You may need to make the downloaded file executable by running chmod +x [file name] on UNIX-like systems.

The server will be available at http://localhost:7654 unless you set a different port.

Checking the version

You can check the version of the executable by running the following command:

./[executable name] -v

Building from source

You can build from source if a release isn't available for your system. Please note that you will need to have Go >= 1.22.3 installed on your system.

First, clone the repository:

git clone https://github.com/BeehiveBroadband/limitr.git
cd limitr

Then, build the executable:

go build ./cmd/limitr

Finally, run the executable:

./limitr

The server will be available at http://localhost:7654 unless you set a different port.

Building from the dev branch (unstable)

If you want to build from the dev branch to get the latest features, you can do so. Please note that the dev branch may contain unstable code. You will need to have Go >= 1.22.3 installed on your system to build from source.

First, clone the repository:

git clone https://github.com/BeehiveBroadband/limitr.git
cd limitr

Then, checkout the dev branch:

git checkout dev

Then, build the executable:

go build ./cmd/limitr

Finally, run the executable:

./limitr

The server will be available at http://localhost:7654 unless you set a different port.

Licensing

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