Horizon, app cache (including public API response cache), Reverb (presence + fan-out / scaling), and Pulse redis ingest all expect a reachable Redis. Without it, run the minimal stack (database queue / cache + log broadcast) and skip Horizon / Pulse redis ingest / Echo.

Full vs minimal: Minimal vs full stack. Queues: Operations. Official: Redis.

What Externa uses Redis for

Feature	Why Redis
Horizon	Queue backend + Horizon meta (`QUEUE_CONNECTION=redis`)
App cache / performance	`CACHE_STORE=redis` on `REDIS_CACHE_DB=1` (distinct from queue DB `0`) — preferred for public API caching; `database` is fine for light local
Reverb + Echo	Scaling / presence pub-sub (Herd Reverb still expects Redis for multi-node; local single-node benefits from Redis for the rest of the stack)
Pulse	`PULSE_INGEST_DRIVER=redis` stream + `pulse:work`

Herd

Enable Redis in Laravel Herd.
Confirm: redis-cli ping → PONG.
PHP needs ext-redis (Herd PHP 8.4 includes it).
Optional: enable Reverb under Herd Services (shared :8080) — see Reverb & Echo.

Operators can check Redis reachability from Settings → Performance (/settings/performance) — the Status section shows whether Redis responds to ping(). See Operations.

Env

REDIS_CLIENT=phpredis
REDIS_HOST=127.0.0.1
REDIS_PASSWORD=null
REDIS_PORT=6379
CACHE_STORE=redis
# Dedicated DBs:
# REDIS_DB=0          # default / Horizon / queues
REDIS_CACHE_DB=1      # app cache (keep separate from queues)
# REDIS_PULSE_DB=2    # Pulse ingest (config/database.php connection "pulse")

Externa registers a dedicated Redis connection named pulse so Pulse ingest does not share Horizon/queue keys (Pulse Redis ingest). Use REDIS_CACHE_DB=1 so Laravel cache keys do not collide with Horizon/queue data on DB 0.

Without Redis

Set:

QUEUE_CONNECTION=database
CACHE_STORE=database
BROADCAST_CONNECTION=log
PULSE_ENABLED=false
# or PULSE_INGEST_DRIVER=storage

Then use composer run dev (queue:listen) instead of Horizon + Pulse workers. Notifications fall back to the 60s unread poll only in this mode.