# Bandit
[](https://github.com/mtrudel/bandit/actions)
[](https://hexdocs.pm/bandit)
[](https://hex.pm/packages/bandit)
Bandit is an HTTP server for Plug apps.
Bandit is written entirely in Elixir and is built atop [Thousand
Island](https://github.com/mtrudel/thousand_island). It can serve HTTP/1.x and HTTP/2 clients over
both HTTP and HTTPS. It is written with correctness, clarity & performance as fundamental goals. It was introduced at [ElixirConf 2021](https://www.youtube.com/watch?v=ZLjWyanLHuk).
In [recent performance
tests](https://github.com/mtrudel/network_benchmark/blob/0b18a9b299b9619c38d2a70ab967831565121d65/benchmarks-09-2021.pdf),
Bandit's HTTP/1.x engine is up to 5x faster than Cowboy depending on the number of concurrent
requests. When comparing HTTP/2 performance, Bandit is up to 2.3x faster than Cowboy (this number
is likely even higher, as Cowboy was unable to complete many test runs without error). This is
possible because Bandit has been built from the ground up for use with Plug applications; this
focus pays dividends in both performance and also in the approachability of the code base.
Bandit also emphasizes correctness. Its HTTP/2 implementation scores 100% on the
[h2spec](https://github.com/summerwind/h2spec) suite in strict mode. Extensive units tests
(90%+ coverage for all non-legacy modules), credo analysis and dialyzer coverage round out a test suite that
ensures that Bandit is and will remain a platform you can count on.
Lastly, Bandit exists to demystify the lower layers of infrastructure code. In a world where
The New Thing is nearly always adding abstraction on top of abstraction, it's important to have
foundational work that is approachable & understandable by users above it in the stack.
## Project Goals
* Implement comprehensive support for HTTP/1.0 through HTTP/2 (and beyond) backed by obsessive RFC
literacy and automated conformance testing
* Aim for minimal internal policy and HTTP-level configuration. Delegate to Plug as much as
possible, and only interpret requests to the extent necessary to safely manage a connection
& fulfill the requirements of supporting Plug
* Prioritize (in order): correctness, clarity, performance. Seek to remove the mystery of
infrastructure code by being approachable and easy to understand
* Become the go-to HTTP & low-level networking stack of choice for the Elixir community by being
reliable, efficient, and approachable
## Project Status
Bandit is still a young project, and much work remains before it is ready for production use. That
having been said, much progress has been made already. The project is progressing steadily
towards full Phoenix support, with a phased development plan focusing on one major set of features
at a time.
As of the current 0.5.x release series, Bandit features the following:
* Complete support for running HTTP(S) Phoenix applications which do not make
use of WebSockets
* Complete support of the [Plug API](https://github.com/elixir-plug/plug)
* Complete server support for HTTP/2 as defined in [RFC
7540](https://datatracker.ietf.org/doc/html/rfc7540), comprehensively covered by automated
[h2spec](https://github.com/summerwind/h2spec) conformance testing
* Complete server support for HTTP/1.x as defined in [RFC
2616](https://datatracker.ietf.org/doc/html/rfc2616)
* Extremely scalable and performant client handling at a rate up to 5x that of Cowboy for the same
workload with as-good-or-better memory use
Today, any HTTP(S)-only Phoenix app or Plug app should work with Bandit as a drop-in replacement for
Cowboy. The roadmap to full Phoenix support and an eventual 1.0 release looks more or less
like the following:
* [x] `0.1.x` series: Proof of concept (along with [Thousand
Island](https://github.com/mtrudel/thousand_island)) sufficient to support
[HAP](https://github.com/mtrudel/hap)
* [x] `0.2.x` series: Revise process model to accommodate forthcoming HTTP/2 and WebSocket
adapters
* [x] `0.3.x` series: Implement HTTP/2 adapter
* [x] `0.4.x` series: Re-implement HTTP/1.x adapter
* [ ] `0.5.x` series: Implement WebSocket extension
* [ ] `0.6.x` series: Enhance startup options, complete & revise documentation & tests
* [ ] `0.7.x` series: Bugfixes from a wider release to ensure a solid 1.0
## Using Bandit With Phoenix
As of the 0.5.x branch Bandit supports Phoenix applications which use HTTP(S).
Phoenix applications which use WebSockets for features such as Channels or LiveView are not yet
supported (though this support is coming soon!).
That having been said, using Bandit to host your Phoenix application couldn't be simpler:
1. Add Bandit as a dependency in your Phoenix application's `mix.exs`:
```elixir
{:bandit, ">= 0.5.0"}
```
2. Add the following to your endpoint configuration in `config/config.exs`:
```elixir
config :your_app, YourAppWeb.Endpoint,
adapter: Bandit.PhoenixAdapter
```
3. That's it! You should now see messages at startup indicating that Phoenix is using Bandit to
serve your endpoint.
## Using Bandit With Plug Applications
Using Bandit to host your own Plug is very straightforward. Assuming you have a Plug module
implemented already, you can host it within Bandit by adding something similar to the following
to your application's `Application.start/2` function:
Usage of Bandit is very straightforward. Assuming you have a Plug module implemented already, you can
host it within Bandit by adding something similar to the following to your application's
`Application.start/2` function:
```elixir
def start(_type, _args) do
children = [
{Bandit, plug: MyApp.MyPlug, scheme: :http, options: [port: 4000]}
]
opts = [strategy: :one_for_one, name: MyApp.Supervisor]
Supervisor.start_link(children, opts)
end
```
Bandit takes a number of options at startup, which are described in detail in the Bandit
[documentation](https://hexdocs.pm/bandit/Bandit.html).
For less formal usage, you can also start Bandit using the same configuration
options via the `Bandit.start_link/1` function:
```
# Start an http server on the default port 4000, serving MyApp.MyPlug
Bandit.start_link(plug: MyApp.MyPlug)
```
## Implementation Details
Bandit's HTTP/2 implementation is described in detail in its own [README](lib/bandit/http2/README.md). Similar documentation for the HTTP/1.x implementation is a work in progress.
## Contributing
Contributions to Bandit are very much welcome! Before undertaking any substantial work, please
open an issue on the project to discuss ideas and planned approaches so we can ensure we keep
progress moving in the same direction.
All contributors must agree and adhere to the project's [Code of
Conduct](https://github.com/mtrudel/bandit/blob/main/CODE_OF_CONDUCT.md).
Security disclosures should be sent privately to mat@geeky.net.
## Installation
Bandit is [available in Hex](https://hex.pm/docs/publish). The package can be installed
by adding `bandit` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:bandit, ">= 0.5.1"}
]
end
```
Documentation can be found at [https://hexdocs.pm/bandit](https://hexdocs.pm/bandit).
# License
MIT
