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0009. Redis-backed queues run by Horizon (single domain) or a queue:work loop (multi-domain)

Generated from api/docs/adr/0009-redis-queues-with-horizon.md

  • Status: Accepted (retroactive); Horizon partially superseded by ADR-0013 in multi-domain mode
  • Date: 2021-09-22

Context and Problem Statement

Section titled “Context and Problem Statement”

Notifications, video processing, imports, reports and broadcasts must run outside the HTTP request. The queue backend and the worker supervisor had to be chosen, and later had to work with many tenants on one deployment (ADR-0013).

Considered Options

Section titled “Considered Options”

Not recorded for the original choice. For multi-domain: the gecche Horizon provider vs. plain queue:work --domain=… per domain (both appear in history).

Decision Outcome

Section titled “Decision Outcome”
  • 2021-09-22 PR #66 added Redis to docker-compose and laravel/horizon with config/horizon.php and a HorizonServiceProvider. Supervisor runs Horizon and, since 821330f6 (2022-04-21), the scheduler (cron.sh replaced by scheduler.conf).
  • 2024-12-04 the multi-domain Horizon provider was removed “as it’s not working for many domains” (1c92ea67). In multi-domain mode init_multidomains.sh disables horizon.conf and enables multidomain_queue.conf, which runs queue.sh: a loop over shuffled MULTI_DOMAINS calling artisan queue:work --queue=default,broadcast,video --max-jobs=20 --stop-when-empty --domain=$domain (eddd25ab, ba4e1170).
  • 2026-03 real-time broadcasting moved to a self-hosted Pusher-compatible Soketi server (f51c206f, pusher/pusher-php-server) with a dedicated broadcast worker (64b80294).

Consequences

Section titled “Consequences”
  • Good: single-domain installs get Horizon’s dashboard and balancing.
  • Good: multi-domain works with any number of tenants without one worker per tenant.
  • Bad: two different worker setups to maintain and debug.
  • Bad: the round-robin loop adds latency proportional to the number of domains and gives no Horizon metrics for tenants.

Evidence

Section titled “Evidence”
  • cbfb1571 2021-09-22 “Feature/docker redis update (#66)” — api/config/horizon.php, api/app/Providers/HorizonServiceProvider.php, api/docker-compose.yml.
  • 821330f6 2022-04-21 “scheduler to supervisor” — api/docker/conf/supervisor/scheduler.conf.
  • 1c92ea67 2024-12-04 “remove horizon multidomain provider as it’s not working for many domains”.
  • eddd25ab 2024-10-10 “making queue worksaand fixing multidomain tool” — api/queue.sh, multidomain_queue.conf.
  • f51c206f 2026-03-06 “Added soketi”; 64b80294 2026-03-13 “Added broadcast queue”.