Choosing a Message Queue on Zerops

Keywords

queue, message queue, kafka, nats, event, stream, pub-sub, broker, choose queue, which queue, messaging

TL;DR

Use NATS for most cases (simple, fast, JetStream persistence). Use Kafka only for enterprise event streaming with guaranteed ordering and unlimited retention.

Decision Matrix

Need	Choice	Why
General messaging	NATS (default)	Simple auth, JetStream built-in, fast
Enterprise event streaming	Kafka	SASL auth, 3-broker HA, unlimited retention
Lightweight pub/sub	NATS	Low overhead, 8MB default messages
Event sourcing / audit logs	Kafka	Indefinite topic retention, strong ordering

NATS (Default Choice)

• Ports: 4222 (client), 8222 (HTTP monitoring)
• Auth: user zerops + auto-generated password
• Connection: nats://${user}:${password}@${hostname}:4222
• JetStream: Enabled by default (JET_STREAM_ENABLED=1)
• Storage: Up to 40GB memory + 250GB file store
• Max message: 8MB default, 64MB max (MAX_PAYLOAD)
• Health check: GET /healthz on port 8222
• Config changes require restart (no hot-reload)

Kafka

• Port: 9092 (SASL PLAIN auth)
• Auth: user + password env vars (auto-generated)
• Bootstrap: ${hostname}:9092
• HA: 3 brokers, 6 partitions, replication factor 3
• Storage: Up to 40GB RAM + 250GB persistent
• Topic retention: Indefinite (no time or size limits)
• Schema Registry: Port 8081 (if enabled)

Gotchas

1. NATS config changes need restart: No hot-reload — changing env vars requires service restart
2. Kafka single-node has no replication: 1 broker = 3 partitions but zero redundancy
3. NATS JetStream HA sync interval: 1-minute sync across nodes — brief data lag possible
4. Kafka SASL only: No anonymous connections — always use the generated credentials

See Also

• zerops://themes/services — NATS, Kafka service cards and wiring
• zerops://decisions/choose-database