Add BGP-LS usage example

README.md

@@ -34,6 +34,7 @@ Try [a binary release](https://github.com/osrg/gobgp/releases/latest).
 - [RPKI](docs/sources/rpki.md)
 - [Managing GoBGP with your favorite language with gRPC](docs/sources/grpc-client.md)
 - [Using GoBGP as a Go Native BGP library](docs/sources/lib.md)
+- [Using BGP-LS in GoBGP library mode](docs/sources/lib-ls.md)
 - [Graceful Restart](docs/sources/graceful-restart.md)
 - [Additional Paths](docs/sources/add-paths.md)
 - [Peer Group](docs/sources/peer-group.md)

docs/sources/lib-ls.md

@@ -0,0 +1,98 @@
+# Using BGP-LS in GoBGP library mode
+
+This page explains how to use GoBGP for getting BGP-LS prefixes.
+
+## Contents
+
+- [Basic BGP-LS Example](#basic-bgp-ls-example)
+
+## Basic BGP-LS Example
+
+```go
+package main
+
+import (
+	"context"
+	"os"
+
+	"github.com/golang/protobuf/jsonpb"
+	api "github.com/osrg/gobgp/api"
+	gobgp "github.com/osrg/gobgp/pkg/server"
+	log "github.com/sirupsen/logrus"
+)
+
+func main() {
+	log.SetLevel(log.DebugLevel)
+	s := gobgp.NewBgpServer()
+	go s.Serve()
+
+	if err := s.StartBgp(context.Background(), &api.StartBgpRequest{
+		Global: &api.Global{
+			As:         64512,
+			RouterId:   "10.0.255.254",
+			ListenPort: -1, // gobgp won't listen on tcp:179
+		},
+	}); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := s.MonitorPeer(context.Background(), &api.MonitorPeerRequest{}, func(p *api.Peer) { log.Info(p) }); err != nil {
+		log.Fatal(err)
+	}
+
+	// neighbor configuration
+	n := &api.Peer{
+		Conf: &api.PeerConf{
+			NeighborAddress: "172.17.0.2",
+			PeerAs:          65002,
+		},
+		ApplyPolicy: &api.ApplyPolicy{
+			ImportPolicy: &api.PolicyAssignment{
+				DefaultAction: api.RouteAction_ACCEPT,
+			},
+			ExportPolicy: &api.PolicyAssignment{
+				DefaultAction: api.RouteAction_REJECT,
+			},
+		},
+		AfiSafis: []*api.AfiSafi{
+			{
+				Config: &api.AfiSafiConfig{
+					Family: &api.Family{
+						Afi:  api.Family_AFI_LS,
+						Safi: api.Family_SAFI_LS,
+					},
+					Enabled: true,
+				},
+			},
+		},
+	}
+
+	if err := s.AddPeer(context.Background(), &api.AddPeerRequest{
+		Peer: n,
+	}); err != nil {
+		log.Fatal(err)
+	}
+
+	marshaller := jsonpb.Marshaler{
+		Indent:   "  ",
+		OrigName: true,
+	}
+
+	// Display incoming Prefixes in JSON format.
+	if err := s.MonitorTable(context.Background(), &api.MonitorTableRequest{
+		TableType: api.TableType_GLOBAL,
+		Family: &api.Family{
+			Afi:  api.Family_AFI_LS,
+			Safi: api.Family_SAFI_LS,
+		},
+	}, func(p *api.Path) {
+		// Your application should do something useful with the BGP-LS path here.
+		marshaller.Marshal(os.Stdout, p)
+	}); err != nil {
+		log.Fatal(err)
+	}
+
+	select {}
+}
+
+```