add registry base interface, mdns, noop implementations, add resolver, client

registry/registry.go

@@ -0,0 +1,54 @@
+// Package registry is an interface for service discovery
+package registry
+
+import (
+	"errors"
+
+	"google.golang.org/grpc/resolver"
+)
+
+var (
+	// Not found error when GetService is called
+	ErrNotFound = errors.New("service not found")
+	// Watcher stopped error when watcher is stopped
+	ErrWatcherStopped = errors.New("watcher stopped")
+)
+
+// The registry provides an interface for service discovery
+// and an abstraction over varying implementations
+type Registry interface {
+	ResolverBuilder() resolver.Builder
+	Init(...Option) error
+	Options() Options
+	Register(*Service, ...RegisterOption) error
+	Deregister(*Service, ...DeregisterOption) error
+	GetService(string, ...GetOption) ([]*Service, error)
+	ListServices(...ListOption) ([]*Service, error)
+	Watch(...WatchOption) (Watcher, error)
+	String() string
+}
+
+type Service struct {
+	Name      string            `json:"name"`
+	Version   string            `json:"version"`
+	Metadata  map[string]string `json:"metadata"`
+	Nodes     []*Node           `json:"nodes"`
+}
+
+type Node struct {
+	Id       string            `json:"id"`
+	Address  string            `json:"address"`
+	Metadata map[string]string `json:"metadata"`
+}
+
+type Option func(*Options)
+
+type RegisterOption func(*RegisterOptions)
+
+type WatchOption func(*WatchOptions)
+
+type DeregisterOption func(*DeregisterOptions)
+
+type GetOption func(*GetOptions)
+
+type ListOption func(*ListOptions)