Igniter Installer

Beta: The Igniter installer is new and under active testing. If you hit an issue, please open a bug report. You can always fall back to manual installation.

The Igniter installer configures polar_express in a Phoenix project with a single command. It wires up webhook verification, scaffolds a controller, and adds the route.

Prerequisites

Your project needs Igniter installed. If you don't have it yet:

# mix.exs
{:igniter, "~> 0.7"}

Running the Installer

mix igniter.install polar_express

If polar_express is already in your deps, run the configuration task directly:

mix polar_express.install

Both commands do the same thing. The only difference is that igniter.install also adds the dependency to your mix.exs.

What It Does

The installer makes four changes to your project. Igniter shows a unified diff of every change and asks for confirmation before writing anything.

1. Explicit Runtime Setup

PolarExpress does not read library application config. Start its Finch pool in your supervision tree:

children = [
  PolarExpress
]

Create clients with explicit credentials:

client =
  PolarExpress.client(System.fetch_env!("POLAR_ACCESS_TOKEN"),
    server: :sandbox
  )

Your deployment environment needs POLAR_ACCESS_TOKEN set.

2. Webhook Plug

Injects PolarExpress.WebhookPlug into your Phoenix endpoint, directly before Plug.Parsers:

# lib/my_app_web/endpoint.ex

plug PolarExpress.WebhookPlug,
  secret: {System, :fetch_env!, ["POLAR_WEBHOOK_SECRET"]},
  path: "/webhook/polar"

plug Plug.Parsers,
  parsers: [:urlencoded, :multipart, :json],
  ...

The plug must come before Plug.Parsers because it needs the raw request body for signature verification. Plug.Parsers consumes the body, so anything after it cannot verify the signature.

If your project has multiple endpoints, Igniter will prompt you to choose which one to modify.

3. Webhook Controller

Scaffolds a controller at lib/<app>_web/controllers/polar_webhook_controller.ex:

defmodule MyAppWeb.PolarWebhookController do
  use MyAppWeb, :controller

  def handle(conn, _params) do
    event = conn.assigns.polar_express_event

    case event.type do
      "order.created" -> ...
      "order.updated"  -> ...
      "subscription.created"     -> ...
      "subscription.updated" -> ...
      unhandled -> Logger.info("Unhandled Polar event: #{unhandled}")
    end

    send_resp(conn, 200, "ok")
  end
end

Each event handler is a stub that logs the event ID. Replace them with your business logic. See the Webhooks guide for details on event handling patterns.

4. Webhook Route

Adds a route to your Phoenix router:

scope "/webhook" do
  post "/polar", MyAppWeb.PolarWebhookController, :handle
end

The path /webhook/polar matches the :path option configured on the plug. If your project has multiple routers, Igniter will prompt you to choose.

After Installation

1. Add PolarExpress to your supervision tree if you use the default Finch pool.

2. Set production environment variables:

   POLAR_ACCESS_TOKEN=pk_live_...
   POLAR_WEBHOOK_SECRET=whsec_live_...

3. Create a webhook endpoint in the Polar Dashboard pointed at https://your-domain.com/webhook/polar

4. Customize the controller event handlers with your business logic

5. Test locally with the Polar CLI or webhooks dashboard to send test events

Re-running the Installer

The installer is safe to run multiple times:

• The controller is only created if the module doesn't exist
• The webhook plug is only injected if not already in the endpoint

If you need to reset and re-run, delete the generated controller file and remove the plug/route lines manually, then run the installer again.

Non-Phoenix Projects

If no Phoenix endpoint or router is found, the installer skips the plug, controller, and route steps. You still get notices explaining how to set up webhook handling manually. See the Webhooks guide for the manual setup instructions.

Dry Run

Preview changes without writing anything:

mix polar_express.install --dry-run