---
id: "raft-event-log"
type: "component"
kind: "event-store"
provider: "default"
category: "messaging"
docs: "https://raft.github.io/"
url: "https://localhost:3000/catalogue/components/raft-event-log"
---

# Raft event log

Generic in-house Raft-replicated append-only log used as journal or sequencer.

| | |
|---|---|
| Provider | [default](https://localhost:3000/catalogue?provider=default) |
| Kind | [Event store](https://localhost:3000/catalogue/kinds/event-store) |
| Category | Messaging |
| Official docs | [https://raft.github.io/](https://raft.github.io/) |

## Properties

| property | type | values | required | kind default | this component |
|---|---|---|---|---|---|
| `journaled` | boolean | — | no | true | **true** |
| `managed` | boolean | — | no | false | inherited |
| `nodes` | integer | — | no | 3 | inherited |
| `replication` | enum | `none`, `raft`, `primary-replica` | no | "none" | **"raft"** |
| `role` | enum | `journal`, `sequencer` | no | "journal" | **"journal"** |
| `snapshotIntervalEvents` | integer | — | no | — | inherited |
| `storage` | enum | `mmap`, `rocksdb`, `database` | no | "database" | **"mmap"** |

Bold values are the ones this component pins.

## Rules that apply · 1

### Stateful engine pinned to a single zone `stateful-engine-pinned-to-single-zone` (error)

- Page: https://localhost:3000/catalogue/rules/stateful-engine-pinned-to-single-zone.md
- Why: A matching engine, coordination service or event store living in exactly one availability zone, with no failover and no replication, is lost with that zone. Everything that depends on it stops with it.
- Applies to: every node of kind matching-engine, coordination-service or event-store
- Message: '{{node.id}}' is pinned to a single availability zone with no failover or replication.

It fires when:

- all of these hold:
  - the node sits inside exactly 1 availability-zone group
  - any of these hold:
    - the node's `failover` is "none"
    - the node's `replicated` is false
    - the node's `replication` is "none"

## Other products of the same kind · 4

- [Axon Server](https://localhost:3000/catalogue/components/axon-server.md) `axon-server` — default
- [Apache BookKeeper](https://localhost:3000/catalogue/components/bookkeeper.md) `bookkeeper` — default
- [Generic event store](https://localhost:3000/catalogue/components/event-store.md) `event-store` — default
- [EventStoreDB](https://localhost:3000/catalogue/components/eventstoredb.md) `eventstoredb` — default

## Use it in a design

```yaml
nodes:
  - { id: "raft-event-log", component: "raft-event-log" }
```

## Source (`component` YAML, verbatim)

```yaml
# yaml-language-server: $schema=../../schema/component.schema.json
# Generic in-house Raft-replicated append-only log (exchange journals, sequencers, custom event stores).
# Three voting nodes and memory-mapped segments are the usual shape.
schemaVersion: "1"
type: "component"
id: "raft-event-log"
kind: "event-store"
provider: "default"
docs: "https://raft.github.io/"
defaults:
  replication: "raft"
  journaled: true
  storage: "mmap"
  role: "journal"
properties:
  nodes:
    type: "integer"
    default: 3
```

Human page: https://localhost:3000/catalogue/components/raft-event-log