Metadata

Metadata is a mechanism to attach arbitrary key-value data to Hook0 objects like events and subscriptions. It allows you to store custom information alongside your webhook data without affecting Hook0's core functionality.

Key Points

• Metadata can be attached to events and subscriptions
• Hook0 stores but does not process metadata
• Metadata is searchable via the Search API
• Not visible to webhook consumers unless explicitly exposed

Metadata vs Labels

A common question is when to use metadata versus labels. They serve different purposes:

+-------------------+     +-------------------+
|     Labels        |     |    Metadata       |
+-------------------+     +-------------------+
| Used for routing  |     | Not used for      |
| events to subs    |     | routing           |
+-------------------+     +-------------------+
| Affects delivery  |     | No effect on      |
|                   |     | delivery          |
+-------------------+     +-------------------+
| Required (min 1)  |     | Optional          |
+-------------------+     +-------------------+

Use labels when you need to route events to specific subscriptions. Use metadata when you need to store additional context for your own systems.

Common Use Cases

• Correlation IDs - Link events to external systems
• User context - Store the user ID who triggered the event
• Debug info - Include request IDs or trace identifiers
• Business context - Store domain-specific identifiers

Description Field

In addition to metadata, a separate description field exists for human-readable annotations. For example: "Customer onboarding webhook for Acme Corp".

Security

Don't store sensitive information (bank accounts, card details, passwords) in metadata or the description field.

What's Next?

• Events - Attach metadata to events
• Subscriptions - Attach metadata to subscriptions
• Labels - Use labels for event routing