go-micro/examples/heartbeat

Heartbeat

A demonstration of using heartbeating with service discovery.

Rationale

Services register with service discovery on startup and deregister on shutdown. Sometimes these services may unexpectedly die or be killed forcefully or face transient network issues. In these cases stale nodes will be left in service discovery. It would be ideal if services were automatically removed.

Solution

Micro supports the option of a register TTL and register interval for this exact reason. TTL specifies how long a registration should exist in discovery after which it expires and is removed. Interval is the time at which a service should re-register to preserve it's registration in service discovery.

These are options made available in go-micro and as flags in the micro toolkit

Toolkit

Run any component of the toolkit with the flags like so

micro --register_ttl=30 --register_interval=15 api

This example shows that we're setting a ttl of 30 seconds with a re-register interval of 15 seconds.

Go Micro

When declaring a micro service you can pass in the options as time.Duration

service := micro.NewService(
	micro.Name("com.example.srv.foo"),
	micro.RegisterTTL(time.Second*30),
	micro.RegisterInterval(time.Second*15),
)