Deploying on Fly.io

View Source

Elixir WebRTC-based apps can be easily deployed on Fly.io!

There are just three things you need to do:

  • configure a STUN server both on the client and server side
  • use a custom Fly.io IP filter on the server side
  • slightly modify the auto-generated Dockerfile

In JavaScript code:

pc = new RTCPeerConnection({
  iceServers: [{ urls: "stun:stun.l.google.com:19302" }],
});

In Elixir code:

ip_filter = Application.get_env(:your_app, :ice_ip_filter)

{:ok, pc} =
  PeerConnection.start_link(
    ice_ip_filter: ip_filter,
    ice_servers: [%{urls: "stun:stun.l.google.com:19302"}]
  )

In runtime.exs:

if System.get_env("FLY_APP_NAME") do
  config :your_app, ice_ip_filter: &ExWebRTC.ICE.FlyIpFilter.ip_filter/1
end

Now:

  1. Run fly launch. It will generate a Dockerfile that will fail to build.

  2. Introduce the following changes 

     - ARG ELIXIR_VERSION=1.16.0
 - ARG OTP_VERSION=26.2.1
 - ARG DEBIAN_VERSION=bullseye-20231009-slim
 + ARG ELIXIR_VERSION=1.17.2
 + ARG OTP_VERSION=27.0.1
 + ARG DEBIAN_VERSION=bookworm-20240701-slim

 # when building on arm64, you will also need to add libsrtp2-dev
 - RUN apt-get update -y && apt-get install -y build-essential git \
 -     && apt-get clean && rm -f /var/lib/apt/lists/*_*
 + RUN apt-get update -y && apt-get install -y build-essential git pkg-config libssl-dev \
 +     && apt-get clean && rm -f /var/lib/apt/lists/*_*

  3. Run fly deploy to retry.

That's it! No special UDP port exports or dedicated IP address are needed :)