oban-designer

# Oban Designer

## Installation

```elixir
# mix.exs
{:oban, "~> 2.18"}

# config/config.exs
config :my_app, Oban,
  repo: MyApp.Repo,
  queues: [default: 10, mailers: 20, webhooks: 50, events: 5],
  plugins: [
    Oban.Plugins.Pruner,
    {Oban.Plugins.Cron, crontab: [
      {"0 2 * * *", MyApp.Workers.DailyCleanup},
      {"*/5 * * * *", MyApp.Workers.MetricsCollector}
    ]}
  ]

# In application.ex children:
{Oban, Application.fetch_env!(:my_app, Oban)}
```

Generate the Oban migrations:

```bash
mix ecto.gen.migration add_oban_jobs_table
```

```elixir
defmodule MyApp.Repo.Migrations.AddObanJobsTable do
  use Ecto.Migration
  def up, do: Oban.Migration.up(version: 12)
  def down, do: Oban.Migration.down(version: 1)
end
```

## Worker Implementation

### Basic Worker

```elixir
defmodule MyApp.Workers.SendEmail do
  use Oban.Worker,
    queue: :mailers,
    max_attempts: 5,
    priority: 1

  @impl Oban.Worker
  def perform(%Oban.Job{args: %{"to" => to, "template" => template} = args}) do
    case MyApp.Mailer.deliver(to, template, args) do
      {:ok, _} -> :ok
      {:error, :temporary} -> {:error, "temporary failure"}  # Will retry
      {:error, :permanent} -> {:cancel, "invalid address"}   # Won't retry
    end
  end
end
```

### Return Values

| Return | Effect |
|--------|--------|
| `:ok` | Job marked complete |
| `{:ok, result}` | Job marked complete |
| `{:error, reason}` | Job retried (counts as attempt) |
| `{:cancel, reason}` | Job cancelled, no more retries |
| `{:snooze, seconds}` | Re-scheduled, doesn't count as attempt |
| `{:discard, reason}` | Job discarded (Oban 2.17+) |

## Queue Configuration

See [references/worker-patterns.md](references/worker-patterns.md) for common worker patterns.

### Sizing Guidelines

| Queue | Concurrency | Use Case |
|-------|------------|----------|
| `default` | 10 | General-purpose |
| `mailers` | 20 | Email delivery (I/O bound) |
| `webhooks` | 50 | Webhook delivery (I/O bound, high volume) |
| `media` | 5 |...