> ## Documentation Index
> Fetch the complete documentation index at: https://docs.prisme.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Redis

> Role, configuration, backup, scaling and updates for Redis in Prisme.ai self-hosted deployments.

## Role in the platform

Redis serves multiple purposes:

| Purpose                          | Service                                     | Notes                                |
| -------------------------------- | ------------------------------------------- | ------------------------------------ |
| **Event broker** (Redis Streams) | All backend services                        | Backs the platform's event bus.      |
| **Contexts cache**               | `prismeai-runtime`                          | Hot state for in-flight automations. |
| **Sessions store**               | `prismeai-api-gateway`                      | Login sessions.                      |
| **Crawler search engine state**  | `prismeai-crawler`, `prismeai-searchengine` | Per-engine queues and state.         |

By convention, each purpose uses a distinct logical Redis `db` number (or a dedicated cluster).

<Note>
  Redis is no longer used as a vector database since the v27 platform. The Knowledges vector store now lives on [Elasticsearch or OpenSearch](/self-hosting/databases/elasticsearch). `RedisJSON` and `RediSearch` modules are not required.
</Note>

## Version compatibility

* **Minimum: Redis 6.2+**.
* Redis 7.x supported and recommended.
* Standard Redis is sufficient — no special modules required.

## Recommended deployment

| Provider            | Recommended service                             | Notes                    |
| ------------------- | ----------------------------------------------- | ------------------------ |
| AWS                 | ElastiCache for Redis (cluster mode), Multi-AZ. |                          |
| Azure               | Azure Managed Redis.                            |                          |
| GCP                 | Memorystore for Redis.                          |                          |
| OpenShift / on-prem | Redis Operator or StatefulSet.                  | At least 3 nodes for HA. |

**Topology**: Multi-AZ for HA. Minimum: 3 GB RAM, 2 vCPU per instance.

We recommand 2 separate instances : one dedicated to the event broker, and another for everything else (cache/sessions).

## Helm Configuration

Helm keys that point to Redis:

<CodeGroup>
  ```yaml prismeai-core-values.yml theme={null}
  global:
    broker:
      driver: redis
      existingSecret: "core-broker"             # url, password

  prismeai-api-gateway:
    storage:
      sessions:
        driver: redis
        existingSecret: "core-prismeai-api-gateway-sessions-store"

  prismeai-runtime:
    cache:
      contexts:
        driver: redis
        existingSecret: "core-prismeai-runtime-cache"
  ```

  ```yaml prismeai-apps-values.yml theme={null}
  global:
    storage:
      searchengines:
        existingSecret: "apps-crawler-searchengines"  # Redis URL with `db` number
  ```
</CodeGroup>

Each secret holds a `url` (e.g. `redis://user:password@host:6379/3`) and optionally `password`.

By convention we allocate `db` numbers per service (e.g. 0 = broker, 2 = runtime cache, 3 = sessions, 4 = searchengines). Adjust when sharing a cluster.

See [Helm install](/self-hosting/kubernetes/helm) for the full install context.

## Redis configuration

### `maxmemory-policy` per instance

Despite the "cache" naming, the runtime contexts cache and the crawler search engine state are **not** LRU caches — both hold operational state that must not disappear mid-operation. Set the eviction policy per Redis instance:

| Redis instance                                                                | Recommended `maxmemory-policy` | Why                                                                                                                                                                                     |
| ----------------------------------------------------------------------------- | ------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Runtime contexts cache** (`prismeai-runtime`)                               | **`noeviction`**               | Evicting an in-flight automation context causes the automation to fail. Size the instance so memory is never the bottleneck — alert on `used_memory` instead.                           |
| **Crawler search engine state** (`prismeai-crawler`, `prismeai-searchengine`) | **`noeviction`**               | Holds queues and per-engine state. Eviction silently drops crawl progress.                                                                                                              |
| **Sessions store** (`prismeai-api-gateway`)                                   | **`noeviction`**               | Evicting a session logs the user out without warning.                                                                                                                                   |
| **Event broker** (Redis Streams, all services)                                | **`allkeys-lru`**              | Stream lengths are already capped by `maxLen`, and unread messages can be re-emitted by upstream producers — LRU eviction is safe and protects the instance from runaway memory growth. |

If you co-locate several of these on a single Redis instance (via distinct `db` numbers), the **strictest** policy wins — `noeviction` — so plan capacity accordingly. The recommended layout is 2 separate instances for broker & everything else.

## Backup & restore

### RDB snapshots

```conf theme={null}
# redis.conf
save 900 1
save 300 10
save 60 10000
```

Trigger a snapshot manually and copy the dump file:

```bash theme={null}
redis-cli -h <host> -a <password> SAVE
cp /var/lib/redis/dump.rdb /backup/redis/dump_$(date +%Y%m%d).rdb
```

### AOF (append-only file)

For lower RPO, enable AOF in addition to RDB:

```conf theme={null}
appendonly yes
appendfsync everysec
```

### Managed services

* **ElastiCache**: enable automatic daily snapshots, retain ≥ 7 days.
* **Azure Managed Redis**: enable RDB persistence to a storage account.
* **Memorystore**: enable scheduled exports to GCS.

Operational strategy (RPO/RTO, retention) lives in [Operations / Backup](/self-hosting/operations/backup).

### What's safe to lose

* **Broker (Redis Streams)**: only contains in-flight events with a `maxLen` cap. Losing it triggers re-processing at worst.
* \*\*Runtime \*\*: active users encounter issues until runtime restart
  * Contexts cache is rebuildable on prismeai-runtime restart
  * Scheduled automations would also be lost until their next save (or a simple platform pull for Prisme.ai AI products)
* **Sessions store**: users won't be disconnected as we use stateless JWK, no impact.

However and in case of a loss of the **Crawler dedicated redis**, the created crawlers would stop working. Their auto reconstruction still need some scipting/automation in Prismeai Platform

## Updates

* Redis is forward-compatible across minor versions; the platform requires **6.2+**.
* Cluster-mode support has been available in Prisme.ai since v3.2.
* For major Redis upgrades (e.g. 6 → 7): plan a maintenance window and fail over the replica.

See [Operations / Updates](/self-hosting/operations/updates).

## Scaling

* **Vertical**: increase memory and IOPS — Redis is memory-bound.
* **Cluster mode**: shard the keyspace for horizontal scale. Useful when broker streams grow beyond a single node's RAM.
* **Replicas**: add read replicas if you offload read-heavy queries.
* **Monitoring**: track memory usage, connected clients, command latency, evicted keys.