---
title: "Propagate Events"
url: "https://docs.caracal.run/architecture/event-streams/"
markdown_url: "https://docs.caracal.run/markdown/architecture/event-streams.md"
description: "Redis Streams, transactional outboxes, consumer groups, and replay paths in Caracal."
page_type: "architecture"
concepts: []
requires: []
---

# Propagate Events

Canonical URL: https://docs.caracal.run/architecture/event-streams/
Markdown URL: https://docs.caracal.run/markdown/architecture/event-streams.md
Description: Redis Streams, transactional outboxes, consumer groups, and replay paths in Caracal.
Page type: architecture
Concepts: none
Requires: none

---

Caracal uses Postgres outboxes for durable enqueue and Redis Streams for asynchronous delivery. Published modes sign stream messages with `STREAMS_HMAC_KEY`.

## Event Pipeline

```mermaid
flowchart LR
  Tx[Postgres transaction] --> Outbox[event_outbox or caracal_outbox]
  Outbox --> Redis[Redis Streams]
  Redis --> Consumers[Consumers]
  Consumers --> Effects[Policy reload, revocation, audit ingest, relay]
  Producers[STS/Gateway audit emitters] --> Replay[Audit replay directory]
  Replay --> Redis
```

## Streams

| Stream | Producers | Consumers |
| --- | --- | --- |
| `caracal.audit.events` | API, STS, Gateway, Coordinator, Control | Audit `audit-ingestor`, SIEM exporters |
| `caracal.audit.events.dlq` | Audit | DLQ observers |
| `caracal.policy.invalidate` | API | STS policy loader |
| `caracal.sessions.revoke` | API/Coordinator | STS and resource/Gateway revocation consumers |
| `caracal.keys.invalidate` | API/STS | STS key caches |
| `caracal.agents.lifecycle` | Coordinator | Coordinator lifecycle relay job |
| `caracal.invocations.lifecycle` | Coordinator | Invocation observers |
| `caracal.delegations.invalidate` | Coordinator | Delegation observers |
| `caracal.providers.ratelimit` | Redis provisioner/provider coordination | Provider rate-limit coordination |

## Outbox Behavior

| Outbox | Owner | Behavior |
| --- | --- | --- |
| `event_outbox` | API | Durable enqueue inside API transactions, cooperative dispatcher, signed Redis `XADD`, retry/backoff, dead-row metrics. |
| `caracal_outbox` | Coordinator | Dedupe by producer/topic/dedupe key and publishes Coordinator topics. |

## Audit Replay

STS and Gateway use replay directories under `/var/lib/caracal/audit-replay`. When Redis or Audit is unavailable, replay files preserve pending audit events so they can drain after recovery.

## Next Step

Use [Store State](/architecture/storage-model/) to understand which data is durable, transient, or recoverable.

## Related Pages

- [Operate Redis Streams](/operations/redis/)
- [Ingest Audit Evidence](/services/audit/)
- [Use Event Topics](/api/event-topics/)