grpclb

README

grpclb

External Load Balancing Service solution for gRPC written in Go. The approach follows the proposal outlined by the core gRPC team.

grpclb load-balancer provides a neutral API which can be integrated with various service discovery frameworks. An example service discovery implementation is provided for Consul.

Usage

Load Balancer

Please also see the bootstrap for Consul backed load-balancers as a reference for building load balancers. Either use the command directly or build your very own.

Server

Servers can optionally report load to the Load Balancer. An example:

See Documentation

Client

See Documentation

Documentation

Index

• func NewResolver(opt *Options) naming.Resolver
• func PickFirst(opt *Options) grpc.Balancer
• type Options

Examples

• NewResolver
• PickFirst

Functions

func NewResolver

func NewResolver(opt *Options) naming.Resolver

NewResolver creates a naming resolver

Example

const target = "helloworld"

// Create a round-robin load-balancer
balancer := grpc.RoundRobin(NewResolver(&Options{
	Address: "127.0.0.1:8383",
}))

// Set up a load-balanced connection to the server.
conn, err := grpc.Dial(target, grpc.WithInsecure(), grpc.WithBalancer(balancer))
if err != nil {
	log.Fatalf("did not connect: %v", err)
}
defer conn.Close()

c := pb.NewGreeterClient(conn)
r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: "world"})
if err != nil {
	log.Fatalf("could not greet: %v", err)
}
log.Printf("Greeting: %s", r.Message)

func PickFirst

func PickFirst(opt *Options) grpc.Balancer

PickFirst returns a Balancer that always selects the first address returned from the Resolver

Example

const target = "helloworld"

// Create a pick-first load-balancer
balancer := PickFirst(&Options{
	Address: "127.0.0.1:8383",
})

// Set up a load-balanced connection to the server.
conn, err := grpc.Dial(target, grpc.WithInsecure(), grpc.WithBalancer(balancer))
if err != nil {
	log.Fatalf("did not connect: %v", err)
}
defer conn.Close()

c := pb.NewGreeterClient(conn)
r, err := c.SayHello(context.Background(), &pb.HelloRequest{Name: "world"})
if err != nil {
	log.Fatalf("could not greet: %v", err)
}
log.Printf("Greeting: %s", r.Message)

Types

type Options

type Options struct {
	// Address is the address of the load balancer.
	// Default: 127.0.0.1:8383
	Address string
	// DialOptions define custom dial options.
	// Default: [WithInsecure].
	DialOptions []grpc.DialOption
	// UpdateInterval is the query interval for
	// updating known servers.
	// Default: 2s
	UpdateInterval time.Duration
}

Options is the picker configuration