Oban Background Jobs Reference

Quick reference for Elixir Oban patterns.

Oban Pro Detection

Before applying patterns, check for Oban Pro:

grep -E "oban_pro|oban_web" mix.exs
grep -r "use Oban.Pro.Worker" lib/

If Oban Pro detected, see references/oban-pro-basics.md for key differences:

Pro features covered: Workflows, Batches, Structured/Recorded/Encrypted workers. See references/oban-pro-basics.md for patterns. For Pro plugins (Lifeline, Smart Engine, DynamicPrioritizer), consult oban.pro/docs.

Iron Laws — Never Violate These

1. •JOBS MUST BE IDEMPOTENT — Safe to retry. Use idempotency keys for payments
2. •JOBS MUST STORE IDs, NOT STRUCTS — JSON serialization. %{user_id: 1} not %{user: %User{}}
3. •JOBS MUST HANDLE ALL RETURN VALUES — :ok, {:error, _}, {:cancel, _}, {:snooze, _}
4. •ARGS USE STRING KEYS — Pattern match %{"user_id" => id} not %{user_id: id}
5. •UNIQUE CONSTRAINTS FOR USER ACTIONS — Prevent double-click duplicates
6. •NEVER STORE LARGE DATA IN ARGS — Store references (IDs, paths), not content

Quick Worker Template

defmodule MyApp.Workers.ExampleWorker do
  use Oban.Worker,
    queue: :default,
    max_attempts: 5,
    unique: [period: {5, :minutes}, keys: [:entity_id]]

  @impl Oban.Worker
  def perform(%Oban.Job{args: %{"entity_id" => id}}) do
    case process(id) do
      {:ok, _} -> :ok
      {:error, :not_found} -> {:cancel, "Entity not found"}
      {:error, :rate_limited} -> {:snooze, {5, :minutes}}
      {:error, reason} -> {:error, reason}
    end
  end
end

Return Value Meanings

Quick Decisions

Which Queue?

• •Critical operations → High concurrency (20+)
• •Mailers/Webhooks (I/O) → Medium concurrency (30-50)
• •CPU-intensive → Low concurrency (3-5)
• •External APIs → Use dispatch_cooldown for rate limiting

Testing Pattern

use Oban.Testing, repo: MyApp.Repo

# Assert enqueued
assert_enqueued worker: MyApp.Worker, args: %{id: 1}

# Execute and verify
assert :ok = perform_job(MyApp.Worker, %{id: 1})

Common Anti-patterns

References

For detailed patterns, see:

• •references/worker-patterns.md - Worker options, backoff, timeout
• •references/queue-config.md - Queue design, pool sizing, cron
• •references/testing-patterns.md - Testing, assertions, drain