---
name: oban
description: "Oban job processing — workers, perform/1 (OSS) and process/1 (Pro), queues, cron, retries, unique jobs, idempotency, Oban Pro (Workflow, Batch, Chunk, Smart Engine), Testing. Use when writing Oban workers, queue config, or debugging jobs."
effort: medium
user-invocable: false
paths:
- "**/workers/**/*.ex"
- "**/*_worker.ex"
- "**/*_worker_test.exs"
- "**/*_job.ex"
---
# Oban Background Jobs Reference
Quick reference for Elixir Oban patterns.
## Oban Pro Detection
**Before applying patterns, check for Oban Pro:**
```bash
grep -E "oban_pro|oban_web" mix.exs
grep -r "use Oban.Pro.Worker" lib/
grep -r "Oban.Pro.Engines.Smart" config/
```
**If Oban Pro detected**, use Pro patterns for ALL new workers:
| Standard Oban | Oban Pro |
|---------------|----------|
| `use Oban.Worker` | `use Oban.Pro.Worker` |
| `def perform(%Job{})` | `def process(%Job{})` |
| `Oban.Testing` | `Oban.Pro.Testing` |
| Advisory lock engine | `Oban.Pro.Engines.Smart` |
**Pro features** (all optional): `args_schema` (typed args), Workflows, Batches, Chunks,
Relay, hooks, encryption, deadlines, chaining, Smart Engine (global concurrency + rate limiting).
Pro plugins (DynamicCron, DynamicLifeline, DynamicPruner) **enhance** OSS equivalents — swap module, don't run both.
See `${CLAUDE_SKILL_DIR}/references/oban-pro-basics.md` for all patterns and migration guide.
---
## 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
7. **SMART ENGINE: NEVER USE `attempt` TO LIMIT SNOOZES** — Snooze rolls back attempt counter. Use `meta["snoozed"]` instead. Causes infinite loops
## Quick Worker Template
```elixir
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
| Return | State | Behavior |
|--------|-------|----------|
| `:ok` | `completed` | Success |
| `{:ok, value}` | `completed` | Success with value |
| `{:error, reason}` | `retryable` | Retry with backoff |
| `{:cancel, reason}` | `cancelled` | Stop permanently |
| `{:snooze, seconds}` | `scheduled` | Delay and retry |
## 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
```elixir
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
| Wrong | Right |
|-------|-------|
| `%{user_id: id}` pattern match | `%{"user_id" => id}` (string keys) |
| `%{user: %User{}}` in args | `%{user_id: 1}` (IDs only) |
| No idempotency for payments | Use idempotency keys |
| Ignoring return values | Handle all outcomes explicitly |
## References
For detailed patterns, see:
- `${CLAUDE_SKILL_DIR}/references/worker-patterns.md` - Worker options, backoff, timeout
- `${CLAUDE_SKILL_DIR}/references/queue-config.md` - Queue design, pool sizing, cron, Smart Engine
- `${CLAUDE_SKILL_DIR}/references/testing-patterns.md` - Testing, assertions, drain (OSS + Pro)
- `${CLAUDE_SKILL_DIR}/references/oban-pro-basics.md` - Pro.Worker, Workflow, Batch, Chunk, Relay, plugins