towerops/vendor/oban_pro/usage-rules/plugins.md

# Plugins

## Available Plugins

- `DynamicCron`: Runtime-configurable cron scheduling with cluster-wide coordination
- `DynamicLifeline`: Rescues orphaned jobs, repairs stuck workflows/chains
- `DynamicPrioritizer`: Automatically increases priority of waiting jobs
- `DynamicPruner`: Flexible job retention with per-queue/worker rules
- `DynamicQueues`: Persists queue configuration across restarts
- `DynamicScaler`: Auto-scales cloud infrastructure based on queue depth

## DynamicCron

Runtime-configurable cron with cluster-wide coordination. Unlike standard Oban cron, DynamicCron
supports runtime updates, guaranteed scheduling, and automatic sync.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicCron,
 timezone: "Etc/UTC",
 sync_mode: :automatic,
 crontab: [
   {"*/5 * * * *", MyApp.Workers.FrequentWorker},
   {"0 0 * * *", MyApp.Workers.DailyWorker, guaranteed: true},
   {"0 9 * * MON", MyApp.Workers.WeeklyWorker, timezone: "America/New_York"},
   {"@reboot", MyApp.Workers.StartupWorker}
 ]}
```

### Options

- `timezone` — default timezone for all entries (defaults to `"Etc/UTC"`)
- `sync_mode` — `:automatic` syncs crontab entries to the database on startup, removing stale
  entries; `:manual` requires explicit `insert/1` and `delete/1` calls
- `guaranteed` — per-entry option that ensures missed jobs are inserted when the system comes back
  online (use for critical scheduled tasks)

### Runtime Management

```elixir
alias Oban.Pro.Plugins.DynamicCron

# Insert or update entries at runtime
DynamicCron.insert({"0 * * * *", MyApp.HourlyWorker})

# Delete an entry
DynamicCron.delete(MyApp.HourlyWorker)

# Get an entry's details
DynamicCron.get(MyApp.HourlyWorker)

# List all entries
DynamicCron.all()
```

## DynamicLifeline

Rescues orphaned jobs and repairs stuck workflows and chains. Essential for production systems
where nodes may crash or restart unexpectedly.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicLifeline, retry_discarded: false}
```

### Options

- `retry_discarded` — whether to retry discarded workflow/chain jobs when dependencies complete

Do not change the `rescue_interval` option. If you see it configured, remove it—the default is
carefully tuned and changing it causes problems.

### What It Rescues

- **Orphaned jobs** — jobs stuck in `executing` state after a node crash
- **Stuck workflows** — workflows blocked by completed dependencies that weren't properly tracked
- **Stuck chains** — chains that stopped progressing due to missed completion signals
- **Partition backfill** — repopulates rate limit and global limit partitions after restarts

## DynamicPrioritizer

Automatically increases priority of jobs that have been waiting too long. Prevents starvation
of low-priority jobs in busy systems.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicPrioritizer,
 prioritizers: [
   rate: [queue: :default, rate: 1, period: to_timeout(second: 30)],
   once: [queue: :media, threshold: to_timeout(minute: 5), boost: 1]
 ]}
```

### Strategies

- `rate` — continuously boost priority at a fixed rate while waiting
- `once` — boost priority once after a threshold wait time

### Options

- `queue` — target queue (required)
- `rate` — priority boost per period (for `rate` strategy)
- `period` — how often to apply the boost (for `rate` strategy)
- `threshold` — wait time before boosting (for `once` strategy)
- `boost` — how much to increase priority (for `once` strategy, default: 1)

## DynamicPruner

Flexible job retention with per-queue and per-worker rules. More powerful than the standard
Oban pruner with fine-grained control over what gets deleted and when.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicPruner,
 mode: {:max_age, {7, :days}},
 queue_overrides: [
   logs: {:max_age, {1, :day}},
   critical: {:max_age, {30, :days}}
 ],
 worker_overrides: [
   MyApp.AuditWorker: {:max_age, {90, :days}},
   MyApp.TempWorker: {:max_age, {1, :hour}}
 ]}
```

### Modes

- `{:max_age, {count, unit}}` — delete jobs older than the specified age
- `{:max_length, count}` — keep only the most recent N jobs

### Options

- `mode` — default retention rule for all jobs
- `queue_overrides` — per-queue retention rules
- `worker_overrides` — per-worker retention rules (takes precedence over queue rules)
- `state` — which job states to prune (default: `[:completed, :cancelled, :discarded]`)

## DynamicQueues

Persists queue configuration to the database for runtime management. Queues survive restarts
and can be modified without redeploying.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicQueues,
 sync_mode: :automatic,
 queues: [
   default: 10,
   mailers: [local_limit: 20, rate_limit: [allowed: 100, period: {1, :minute}]],
   exports: [local_limit: 5, only: {:node, :=~, "worker"}]
 ]}
```

### Options

- `sync_mode` — `:automatic` syncs queue config to database on startup; `:manual` requires
  explicit API calls
- `queues` — initial queue definitions (same format as standard Oban queues)
- `only` — restrict queue to matching nodes using `{:node, pattern}` or `{:sys_env, key, pattern}`;
  supports operators `:==`, `:!=`, `:=~` for pattern matching

### Runtime Management

```elixir
alias Oban.Pro.Plugins.DynamicQueues

# Add or update a queue
DynamicQueues.insert(:reports, local_limit: 5)

# Pause a queue
DynamicQueues.pause(:reports)

# Resume a queue
DynamicQueues.resume(:reports)

# Scale a queue
DynamicQueues.scale(:reports, local_limit: 20)

# Delete a queue
DynamicQueues.delete(:reports)

# List all queues
DynamicQueues.all()
```

## DynamicScaler

Auto-scales cloud infrastructure based on queue depth and throughput. Scales nodes horizontally
to optimize processing during high traffic and save costs during quiet periods.

### Configuration

```elixir
{Oban.Pro.Plugins.DynamicScaler,
 scalers: [
   range: 1..5,
   cloud: MyApp.Cloud
 ]}
```

### Options

- `cloud` — module implementing the `Oban.Pro.Cloud` behaviour (required)
- `range` — min..max nodes to scale between (required)
- `cooldown` — minimum time between scaling events (default: 120 seconds)
- `queues` — `:all` or list of queues to monitor (default: `:all`)
- `step` — `:none` or max nodes to scale at once (default: `:none`)

### Features

- **Predictive scaling** — calculates optimal scale based on recent trends, not just current depth
- **Multi-cloud** — implement the `Cloud` behaviour for your platform (AWS, Fly, Kubernetes, etc.)
- **Thrashing prevention** — cooldown period prevents rapid scale up/down cycles

### Cloud Behaviour

Implement `Oban.Pro.Cloud` for your platform:

```elixir
defmodule MyApp.Cloud do
  @behaviour Oban.Pro.Cloud

  @impl true
  def init(opts), do: opts

  @impl true
  def current(_opts), do: {:ok, current_node_count()}

  @impl true
  def scale(count, _opts), do: scale_to(count)
end
```