medusa-subscribers

Medusa v2 Subscribers and Scheduled Jobs

Before writing code

Fetch live docs:

1. Fetch https://docs.medusajs.com/learn/fundamentals/events-and-subscribers for subscriber overview
2. Web-search site:docs.medusajs.com subscriber handler function for handler API
3. Web-search site:docs.medusajs.com scheduled jobs cron for scheduled job patterns
4. Web-search site:docs.medusajs.com event module redis for event bus configuration
5. Web-search site:docs.medusajs.com built-in events list for available event names

Subscriber Concept

Subscribers react to events emitted by Medusa workflows and services:

• Asynchronous by default -- do not block the emitting operation
• Registered as files in src/subscribers/
• Each file exports a default handler function and a config object
• Events follow a naming convention: {entity}.{action} (e.g., product.created)

Subscriber File Structure

src/subscribers/
├── product-created.ts     # Reacts to product.created
├── order-placed.ts        # Reacts to order.placed
└── customer-registered.ts # Reacts to customer.created

Each file is auto-discovered -- no manual registration required.

Subscriber Handler Pattern

// src/subscribers/product-created.ts
// Fetch live docs for SubscriberArgs and SubscriberConfig types
import type { SubscriberArgs, SubscriberConfig } from "@medusajs/framework"

export default async function productCreatedHandler(
  { event, container }: SubscriberArgs<{ id: string }>) {
  // event.data.id contains the entity ID — fetch live docs for payload shapes
}

Config Export

// Fetch live docs for SubscriberConfig options
export const config: SubscriberConfig = {
  event: "product.created",
}

Event Naming Conventions

| Domain | Event Examples | |--------|---------------| | Products | product.created, product.updated, product.deleted | | Orders | order.placed, order.canceled, order.completed | | Customers | customer.created, customer.updated | | Cart | cart.created, cart.updated | | Fulfillment | fulfillment.created, fulfillment.canceled | | Payment | payment.captured, payment.refunded | | Inventory | inventory-item.created | | Auth | invite.created, invite.accepted |

Fetch live docs for the complete event list -- events are added and renamed across Medusa releases.

Subscribing to Multiple Events

A single subscriber can listen to multiple events:

// Fetch live docs for multi-event config
export const config: SubscriberConfig = {
  event: ["product.created", "product.updated"],
}

The handler receives the event name in event.name to distinguish which event triggered it.

Event Payload

| Property | Type | Description | |----------|------|-------------| | event.name | string | The event that triggered the subscriber | | event.data | object | Payload emitted by the workflow/service | | event.metadata | object | Internal metadata (event ID, timestamp) |

The data shape varies per event. Typically contains the entity ID(s) affected.

Event Module Configuration

| Module | Transport | Use Case | |--------|-----------|----------| | In-memory (default) | Process memory | Development, single-instance | | Redis Event Module | Redis Pub/Sub | Production, multi-instance |

Redis Event Module Setup

// In medusa-config.ts modules array
// Fetch live docs for Redis event module configuration
{
  resolve: "@medusajs/medusa/event-bus-redis",
  options: { redisUrl: process.env.REDIS_URL },
}

In production, always use the Redis event module to ensure events are delivered across multiple server instances.

Scheduled Jobs

Scheduled jobs run on a cron schedule, independent of events:

Job File Structure

src/jobs/
├── daily-sync.ts          # Daily data synchronization
└── cleanup-expired.ts     # Periodic cleanup

Scheduled Job Skeleton

// src/jobs/daily-sync.ts
// Fetch live docs for MedusaContainer type
import type { MedusaContainer } from "@medusajs/framework"

export default async function dailySyncJob(container: MedusaContainer) {
  const service = container.resolve("my-module")
  // Fetch live docs for job handler API
}

Job Config Export

// Fetch live docs for cron expression format
export const config = {
  name: "daily-sync",
  schedule: "0 0 * * *", // Midnight daily (cron syntax)
}

Common Cron Patterns

| Schedule | Cron Expression | |----------|----------------| | Every minute | | | Every 15 minutes | /15 | | Every hour | 0 | | Daily at midnight | 0 0 | | Weekly on Monday | 0 0 1 | | Monthly on the 1st | 0 0 1 * |

Worker Mode and Jobs

| Worker Mode | Subscribers | Scheduled Jobs | |-------------|------------|----------------| | shared | Processed in-process | Processed in-process | | server | Emitted only, not processed | Not processed | | worker | Processed | Processed |

In production, run a dedicated worker instance to handle subscribers and scheduled jobs separately from HTTP traffic.

Emitting Custom Events

Custom events can be emitted from workflows using the emitEventStep:

// Inside a workflow
// Fetch live docs for emitEventStep import
import { emitEventStep } from "@medusajs/medusa/core-flows"

emitEventStep({ eventName: "custom.event", data: { id: "123" } })

Best Practices

• Keep subscribers lightweight -- offload heavy work to workflows
• Use descriptive file names matching the event they handle
• Always type the event payload generic: SubscriberArgs<{ id: string }>
• Use the Redis event module in production for reliability across instances
• Do not perform synchronous, blocking operations in subscribers
• Use scheduled jobs for periodic tasks -- do not poll from subscribers
• Resolve services from the container, never import directly

Fetch the Medusa subscriber and events documentation for exact event names, payload shapes, and Redis event module configuration before implementing.