Consul

HashiCorp Consul is a multi-cloud service networking platform. It handles Service Discovery, Mesh, and Key/Value storage. 2025 v1.18 focuses on Enterprise reliability.

When to Use

• Service Discovery: Tracking dynamic IPs of microservices (common in Nomad/VM setups).
• Service Mesh: mTLS and Traffic split across VMs and K8s.
• KV Store: Storing dynamic configuration distributed across regions.

Core Concepts

Agent

Runs on every node (client mode) or dedicated servers (server mode). Handles health checks.

Service Definition

Register services via Config file or API. {"service": {"name": "web", "port": 80}}

Connect (Mesh)

Uses Envoy to secure traffic between services.

Best Practices (2025)

Do:

• Use DNS Interface: Apps can find DBs via db.service.consul.
• Use Template: consul-template renders config files from KV data and reloads apps automatically.
• Separate Data Centers: Federation allows global service discovery.

Don't:

• Don't expose API publicly: Consul has no default auth in dev mode. Lock it down.

References

• Consul Documentation