Add command option

cmd/cmd.go

@@ -19,6 +19,7 @@ import (
 	"github.com/micro/go-micro/broker"
 	"github.com/micro/go-micro/client"
 	"github.com/micro/go-micro/registry"
+	"github.com/micro/go-micro/selector"
 	"github.com/micro/go-micro/server"
 	"github.com/micro/go-micro/transport"
 	"github.com/pborman/uuid"
@@ -80,6 +81,12 @@ var (
 			EnvVar: "MICRO_REGISTRY_ADDRESS",
 			Usage:  "Comma-separated list of registry addresses",
 		},
+		cli.StringFlag{
+			Name:   "selector",
+			EnvVar: "MICRO_SELECTOR",
+			Value:  "selector",
+			Usage:  "Selector used to pick nodes for querying. random, roundrobin, blacklist",
+		},
 		cli.StringFlag{
 			Name:   "transport",
 			EnvVar: "MICRO_TRANSPORT",
@@ -137,6 +144,10 @@ var (
 		"consul": registry.NewRegistry,
 	}
 
+	Selectors = map[string]func(...selector.Option) selector.Selector{
+		"random": selector.NewSelector,
+	}
+
 	Transports = map[string]func([]string, ...transport.Option) transport.Transport{
 		"http": transport.NewTransport,
 	}
@@ -214,6 +225,10 @@ func Setup(c *cli.Context) error {
 		registry.DefaultRegistry = r(strings.Split(c.String("registry_address"), ","))
 	}
 
+	if s, ok := Selectors[c.String("selector")]; ok {
+		selector.DefaultSelector = s(selector.Registry(registry.DefaultRegistry))
+	}
+
 	if t, ok := Transports[c.String("transport")]; ok {
 		transport.DefaultTransport = t(strings.Split(c.String("transport_address"), ","))
 	}