oban-thinking

Oban Thinking

Paradigm shifts for Oban job processing. These insights prevent common bugs and guide proper patterns.

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Part 1: Oban (Non-Pro)

The Iron Law: JSON Serialization

JOB ARGS ARE JSON. ATOMS BECOME STRINGS.

This single fact causes most Oban debugging headaches.

# Creating - atom keys are fine
MyWorker.new(%{user_id: 123})

# Processing - must use string keys (JSON converted atoms to strings)
def perform(%Oban.Job{args: %{"user_id" => user_id}}) do
  # ...
end

Error Handling: Let It Crash

Don't catch errors in Oban jobs. Let them bubble up to Oban for proper handling.

Why?

1. Automatic logging: Oban logs the full error with stacktrace
2. Automatic retries: Jobs retry with exponential backoff
3. Visibility: Failed jobs appear in Oban Web dashboard
4. Consistency: Error states are tracked in the database

Anti-Pattern

# Bad: Swallowing errors
def perform(%Oban.Job{} = job) do
  case do_work(job.args) do
    {:ok, result} -> {:ok, result}
    {:error, reason} ->
      Logger.error("Failed: #{reason}")
      {:ok, :failed}  # Silently marks as complete!
  end
end

Correct Pattern

# Good: Let errors propagate
def perform(%Oban.Job{} = job) do
  result = do_work!(job.args)  # Raises on failure
  {:ok, result}
end

# Or return error tuple - Oban treats as failure
def perform(%Oban.Job{} = job) do
  case do_work(job.args) do
    {:ok, result} -> {:ok, result}
    {:error, reason} -> {:error, reason}  # Oban will retry
  end
end

When to Catch Errors

Only catch errors when you need custom retry logic or want to mark a job as permanently failed:

def perform(%Oban.Job{} = job) do
  case external_api_call(job.args) do
    {:ok, result} -> {:ok, result}
    {:error, :not_found} -> {:cancel, :resource_not_found}  # Don't retry
    {:error, :rate_limited} -> {:snooze, 60}  # Retry in 60 seconds
    {:error, _} -> {:error, :will_retry}  # Normal retry
  end
end