---
title: Redis Streams
type: entity
created: 2026-04-30
updated: 2026-04-30
sources: [gps-tracking-architecture, teltonika-ingestion-architecture]
tags: [infrastructure, telemetry-plane, queue]
---

# Redis Streams

The durable in-flight queue between [[tcp-ingestion]] and [[processor]]. Also the transport for Phase 2 outbound commands.

## What it provides

- **Buffering** — temporary slowness in [[processor]] does not push back on Ingestion sockets.
- **Replayability** — Streams retain messages, so a Processor crash does not lose telemetry; consumer-group offsets resume from the last position.
- **Horizontal scaling** — multiple Processor instances join a consumer group and split load across device IDs.

## Why Redis (and not Kafka/NATS)

Sufficient at current scale and adds minimal operational burden. NATS or Kafka are reasonable upgrades when **multi-region durability** or **very high throughput** become real concerns. Until then, Redis is the right choice.

## Phase 2 usage

Outbound commands ride on per-instance streams: `commands:outbound:{instance_id}`. Responses ride on `commands:responses`. Redis is the transport; the source of truth for commands is the Directus `commands` collection. See [[phase-2-commands]].

The connection registry (`connections:registry` hash) and per-instance heartbeats (`instance:heartbeat:{instance_id}` keys with `EX 90`) also live in Redis.

## Failure mode

Streams are persisted; restart resumes from disk. Complete Redis loss is recoverable from device retransmits and Processor checkpointing. See [[failure-domains]].

## Operational note

**Consumer lag is the canary metric** for the entire telemetry pipeline. Observability dashboards should make it prominent.

## Deployment

Internal-only container. Persistence enabled. Never exposed externally.