# launchpad-rabbitmq

Helper package to interact with RabbitMQ. Handles connection management, consumer registration, publisher, exponential-backoff reconnect, and consumer health monitoring.

## Setup

```ts
import { rabbitmq, consumer, publisher } from '@polymathnetwork/launchpad-rabbitmq';

rabbitmq.initialize({
  url: RABBITMQ_URL,
  retryDelay: RETRY_DELAY,
  maxRetries: MAX_RETRIES,

  // Reconnect policy (exponential backoff with jitter)
  reconnectDelay: 250,         // base delay for first reconnect attempt (ms)
  maxReconnectDelay: 30_000,   // hard cap on reconnect delay (ms)
  reconnectMultiplier: 2,      // backoff growth factor (default: 2)
  reconnectJitterRatio: 0.2,   // ±20% jitter on each delay (default: 0.2)

  // Health monitoring
  healthLogging: true,         // emit ERROR log when a consumer is lost (default: false)
});

await publisher.initialize();
await consumer.initialize();

// Start consumers — re-registered automatically after reconnect
await consumer.startConsumer(QUEUE_NAME, messageProcessor);
```

## Publishing messages

```ts
import { publisher } from '@polymathnetwork/launchpad-rabbitmq';

const { ack } = await publisher.pushMessage(queueName, message);
```

## Consumer health check

The consumer tracks whether its registered queues have active AMQP consumers. Use this in your `/health` endpoint so Kubernetes can restart the pod if consumers are lost (e.g. due to a TCP disconnect or heartbeat timeout):

```ts
import { consumer } from '@polymathnetwork/launchpad-rabbitmq';

app.get('/health', (_req, res) => {
  if (!consumer.isHealthy()) {
    return res.status(503).json({
      message: 'DEGRADED',
      reason: 'RabbitMQ consumers not active',
      missing: consumer.getMissingQueues(),
    });
  }
  res.json({ message: 'OK', uptime: process.uptime() });
});
```

`isHealthy()` returns `true` during startup (before any consumers are registered) and `false` only after at least one consumer has been registered and subsequently lost.

To toggle logging at runtime instead of via config:

```ts
consumer.enableLogging();   // start emitting ERROR logs on consumer loss
consumer.disableLogging();  // silence them again
```

## `HealthMonitor` (standalone)

If you need a standalone health monitor instance (e.g. for a custom consumer setup not using the built-in `consumer`):

```ts
import { HealthMonitor } from '@polymathnetwork/launchpad-rabbitmq';

const monitor = new HealthMonitor({ logger: myLogger, logging: true });

// After channel.consume() resolves:
monitor.markActive(queueName);
channel.on('close', () => monitor.markInactive(queueName, 'channel closed'));
channel.on('error', (err) => monitor.markInactive(queueName, 'channel error', err.message));
channel.on('cancel', () => monitor.markInactive(queueName, 'consumer cancelled'));

monitor.isHealthy();       // boolean
monitor.getMissingQueues(); // string[]
```