Documentation
¶
Overview ¶
Package naming provides an etcd-backed gRPC resolver for discovering gRPC services.
To use, first import the packages:
import ( "github.com/hanjm/etcd/clientv3" etcdnaming "github.com/hanjm/etcd/clientv3/naming" "google.golang.org/grpc" "google.golang.org/grpc/naming" )
First, register new endpoint addresses for a service:
func etcdAdd(c *clientv3.Client, service, addr string) error {
r := &etcdnaming.GRPCResolver{Client: c}
return r.Update(c.Ctx(), service, naming.Update{Op: naming.Add, Addr: addr})
}
Dial an RPC service using the etcd gRPC resolver and a gRPC Balancer:
func etcdDial(c *clientv3.Client, service string) (*grpc.ClientConn, error) {
r := &etcdnaming.GRPCResolver{Client: c}
b := grpc.RoundRobin(r)
return grpc.Dial(service, grpc.WithBalancer(b))
}
Optionally, force delete an endpoint:
func etcdDelete(c *clientv3, service, addr string) error {
r := &etcdnaming.GRPCResolver{Client: c}
return r.Update(c.Ctx(), service, naming.Update{Op: naming.Delete, Addr: "1.2.3.4"})
}
Or register an expiring endpoint with a lease:
func etcdLeaseAdd(c *clientv3.Client, lid clientv3.LeaseID, service, addr string) error {
r := &etcdnaming.GRPCResolver{Client: c}
return r.Update(c.Ctx(), service, naming.Update{Op: naming.Add, Addr: addr}, clientv3.WithLease(lid))
}
Package naming defines the naming API and related data structures for gRPC.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrWatcherClosed = fmt.Errorf("naming: watch closed")
Functions ¶
This section is empty.
Types ¶
type GRPCResolver ¶
GRPCResolver creates a grpc.Watcher for a target to track its resolution changes.
type Operation ¶
type Operation uint8
Operation defines the corresponding operations for a name resolution change.
type Update ¶
type Update struct {
// Op indicates the operation of the update.
Op Operation
// Addr is the updated address. It is empty string if there is no address update.
Addr string
// Metadata is the updated metadata. It is nil if there is no metadata update.
// Metadata is not required for a custom naming implementation.
Metadata interface{}
}
Update defines a name resolution update. Notice that it is not valid having both empty string Addr and nil Metadata in an Update.
type Watcher ¶
type Watcher interface {
// Next blocks until an update or error happens. It may return one or more
// updates. The first call should get the full set of the results. It should
// return an error if and only if Watcher cannot recover.
Next() ([]*Update, error)
// Close closes the Watcher.
Close()
}
Watcher watches for the updates on the specified target.
Source Files