example_test.go

Documentation: github.com/go-kit/kit/sd/etcd

     1  package etcd
     2  
     3  import (
     4  	"context"
     5  	"io"
     6  	"time"
     7  
     8  	"github.com/go-kit/kit/endpoint"
     9  	"github.com/go-kit/kit/sd"
    10  	"github.com/go-kit/kit/sd/lb"
    11  	"github.com/go-kit/log"
    12  )
    13  
    14  func Example() {
    15  	// Let's say this is a service that means to register itself.
    16  	// First, we will set up some context.
    17  	var (
    18  		etcdServer = "http://10.0.0.1:2379" // don't forget schema and port!
    19  		prefix     = "/services/foosvc/"    // known at compile time
    20  		instance   = "1.2.3.4:8080"         // taken from runtime or platform, somehow
    21  		key        = prefix + instance      // should be globally unique
    22  		value      = "http://" + instance   // based on our transport
    23  		ctx        = context.Background()
    24  	)
    25  
    26  	// Build the client.
    27  	client, err := NewClient(ctx, []string{etcdServer}, ClientOptions{})
    28  	if err != nil {
    29  		panic(err)
    30  	}
    31  
    32  	// Build the registrar.
    33  	registrar := NewRegistrar(client, Service{
    34  		Key:   key,
    35  		Value: value,
    36  	}, log.NewNopLogger())
    37  
    38  	// Register our instance.
    39  	registrar.Register()
    40  
    41  	// At the end of our service lifecycle, for example at the end of func main,
    42  	// we should make sure to deregister ourselves. This is important! Don't
    43  	// accidentally skip this step by invoking a log.Fatal or os.Exit in the
    44  	// interim, which bypasses the defer stack.
    45  	defer registrar.Deregister()
    46  
    47  	// It's likely that we'll also want to connect to other services and call
    48  	// their methods. We can build an Instancer to listen for changes from etcd,
    49  	// create Endpointer, wrap it with a load-balancer to pick a single
    50  	// endpoint, and finally wrap it with a retry strategy to get something that
    51  	// can be used as an endpoint directly.
    52  	barPrefix := "/services/barsvc"
    53  	logger := log.NewNopLogger()
    54  	instancer, err := NewInstancer(client, barPrefix, logger)
    55  	if err != nil {
    56  		panic(err)
    57  	}
    58  	endpointer := sd.NewEndpointer(instancer, barFactory, logger)
    59  	balancer := lb.NewRoundRobin(endpointer)
    60  	retry := lb.Retry(3, 3*time.Second, balancer)
    61  
    62  	// And now retry can be used like any other endpoint.
    63  	req := struct{}{}
    64  	if _, err = retry(ctx, req); err != nil {
    65  		panic(err)
    66  	}
    67  }
    68  
    69  func barFactory(string) (endpoint.Endpoint, io.Closer, error) { return endpoint.Nop, nil, nil }
    70
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