Phoenix 1.6 example app with clustered queue and pool

Sponsored by Hawku.

Features

This app builds on top of Phoenix 1.6 example app with live auth and avatars to play with clustering and specifically with distributed Erlang/Elixir, Oban and libcluster to implement the following features:

• Persistent & clustered transaction queue backed by Oban - each transaction added to the queue is persisted to PostgreSQL database with ACID guarantees and the queue is drained across the entire cluster, all thanks to Oban
• Clustered wallet pool - wallets are divided equally between all nodes in the cluster, with each node maintaining a process pool for its set of wallets and adjusting the Oban transactions queue for concurrency allowing to use all wallets
• Ready-to-go clustering-enabled Fly deployment - including all the config required for app to build the production image, deploy it to Fly, connect the cluster using Fly private networking and use IPv6 for endpoint and database as required

Follow the commit history to see how each was implemented.

Usage

To start the server:

• Install dependencies with mix deps.get
• Create and migrate your database with mix ecto.setup
• Start Phoenix endpoint with mix phx.server or inside IEx with iex -S mix phx.server

To start with local clustering:

• Start node a with PORT=4000 SERVER=1 iex --sname a -S mix
• Start node b with PORT=4001 SERVER=1 iex --sname b -S mix

To deploy to fly

• Create your own app with fly apps create someapp
• Fill the name in fly.toml as app = someapp
• Ensure PostgreSQL is there with fly postgres create and fly postgres attach
• Deploy with fly deploy and visit your app at someapp.fly.dev
• Increase and decrease the node count with fly scale count N and observe the transactions page

Now you can visit localhost:4000 or localhost:4001 from your browser.