benschw / dns-clb-go

Client-Side Load-Balancer for DNS based Service Discovery written in Golang

Deprecated in favor of srv-lb, a rewrite with a cleaner interface.

DNS Client Load Balancer for Go

Selects a SRV record answer according to specified load balancer algorithm, then resolves its A record to an ip, and returns an Address structure:

type Address struct {
	Address string
	Port    uint16
}

Example:

// uses dns server configured in /etc/resolv.conf
srvName := "my-svc.service.consul"
c := clb.New() 
address, err := c.GetAddress(srvName)
if err != nil {
	panic(err)
}

fmt.Printf("%s", address.String())
// Output: 0.1.2.3:8001

or configure explicitely

srvName := "my-svc.service.consul"
c := clb.NewClb("127.0.0.1", "8600", clb.RoundRobin)
address, err := c.GetAddress(srvName)
if err != nil {
	panic(err)
}

fmt.Printf("%s", address.String())
// Output: 0.1.2.3:8001

or use an AddressProvider

// uses dns server configured in /etc/resolv.conf
ap := NewAddressProvider("my-svc.service.consul")
address, err := ap.GetAddress()
if err != nil {
	panic(err)
}

fmt.Printf("%s", address.String())
// Output: 0.1.2.3:8001

Development

tests are run against some fixture dns entries I set up on fligl.io (dig foo.service.fligl.io SRV).

• make deps install deps
• make test run all tests

Notes for Consul / Confd Cluster Demo

This is a fork from the original project https://github.com/benschw/consul-clb-go which contains the demo service used in my blog post outlining how to use Consul for service discovery and configuration management while using Confd and DNS to keep your applications decoupled from the specifics of Consul.

• download demo service here: https://github.com/benschw/consul-clb-go/releases/tag/v0.1.0
• blog post outlining the demo: http://txt.fliglio.com/2014/05/encapsulated-services-with-consul-and-confd/