---
title: 'Event Trigger'
description: 'Starts a workflow when an event of the chosen type arrives.'
---
# Event Trigger

Starts the workflow when an event matching the chosen `eventType` is received by
OneHazel. Events can come from your own code (via `POST /events`), from a
Connection's webhook, or from internal signals like connection health changes.

## When to use

- You want a workflow to fire whenever a specific event happens in your product.
- Examples: "When a transaction is settled, sync it to our accounting tool."
  "When a player's session ends, compute GGR and update their KPIs." "When
  a connection becomes degraded, notify the ops channel."

## Configuration

| Field | Required | What it does |
|---|---|---|
| `eventType` | Yes | The event type string the workflow listens for. Pick from the dropdown or type a custom one. |

## Built-in event types

The dropdown ships with the common iGaming event types plus two connection-
health events:

- `transaction` — player deposit/withdrawal
- `game_activity` — session play events
- `session` — session start/stop
- `bonus` — bonus awarded/consumed
- `block` — account block/unblock
- `support` — support ticket created/updated
- `affiliate` — affiliate-related events
- `connection.health.degraded` — a Connection has started failing health checks
- `connection.health.recovered` — a Connection's health checks are passing again

You can also emit custom event types from your own code — any string works.

## What it outputs

The trigger writes the event payload to the workflow context. Downstream nodes
can reference it as `{{trigger.data.<field>}}`. The exact shape depends on which
event type arrived — see the producer's docs (for a built-in type) or your own
emitter code (for a custom type).

## Deciding between the three trigger types

- **Event Trigger** — for *internal* events OneHazel already knows about, or
  events you emit yourself via `POST /events`.
- **Webhook Trigger** — for *external* systems that can hit a unique URL
  (Stripe webhook, GitHub webhook, custom integration). No pre-existing
  event type needed.
- **Schedule** — for *time-based* runs with no external event (nightly
  rollup, hourly health check, etc.).

## Limitations

- Exactly one trigger node per workflow. If you need multiple trigger
  paths, create multiple workflows.
- `eventType` is matched as an exact string; no wildcards today.