Kujira

Elixir interfaces to Kujira dApps, for building indexers, APIs and bots

N.B. This is currently a work in progress, as we begin to componentise & open source the infrastructure that powers the Kujira dApps

Installation

Add kujira to your list of dependencies in mix.exs:

def deps do
  [
    {:kujira, "~> 0.1.31"}
  ]
end

Connect to a node

Create a MyApp.Node module, configure the application's pubsub and CometBFT subscriptions

defmodule MyApp.Node do
  use Kujira.Node,
    otp_app: :my_app,
    pubsub: MyApp.PubSub,
    subscriptions: ["tm.event='NewBlock'"]
end

Configure the Node connection config/*

config :my_app, MyApp.Node,
  host: "127.0.0.1",
  port: 9090,
  websocket: "wss://rpc-kujira.starsquid.io"

Add the Node process to your application.ex

@impl true
def start(_type, _args) do
  children = [
    #...
    MyApp.Node
  ]

  # ...
end

And start querying!

defmodule MyAppWeb.PageController do
  alias Cosmos.Base.Tendermint
  use MyAppWeb, :controller
  import Tendermint.V1beta1.Service.Stub

  def index(conn, _params) do
    {:ok, %{block: block}} =
      get_latest_block(
        MyApp.Node.channel(),
        Tendermint.V1beta1.GetLatestBlockRequest.new()
      )

    conn |> assign(:block, block) |> render("index.html")
  end
end

CometBFT Events can be subscribed to for realtime applications

defmodule MyAppWeb.PageLive do
  use MyAppWeb, :live_view
  alias Cosmos.Base.Tendermint
  import Tendermint.V1beta1.Service.Stub
  alias Tendermint.V1beta1.GetLatestBlockRequest, as: LatestBlock
  alias Tendermint.V1beta1.GetBlockByHeightRequest, as: Block

  def mount(_params, _session, socket) do
    MyApp.Node.subscribe("tendermint/event/NewBlock")
    {:ok, %{block: block}} = get_latest_block(MyApp.Node.channel(), LatestBlock.new())

    {:ok, assign(socket, :block, block)}
  end

  def handle_info(%{block: %{header: %{height: height}}}, socket) do
    {:ok, %{block: block}} =
      get_block_by_height(
        MyApp.Node.channel(),
        Block.new(height: String.to_integer(height))
      )

    {:noreply, assign(socket, :block, block)}
  end
end

Docs can be found at https://hexdocs.pm/kujira.