From 63ebe41991fa05ab069c35bdacec9706fe96f20d Mon Sep 17 00:00:00 2001
From: Alex Vanin <alexey@nspcc.ru>
Date: Tue, 12 Jan 2021 16:25:30 +0300
Subject: [PATCH] [#304] cmd/neofs-node: Select random NEO endpoints from the
 list

Application should support several NEO endpoints so it can
switch between different RPC nodes when they fail. Application
iterates over endpoints in random order so the default list of
endpoints distribute workload kinda uniformly.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>
---
 cmd/neofs-node/config.go |  4 +--
 cmd/neofs-node/morph.go  | 71 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 68 insertions(+), 7 deletions(-)

diff --git a/cmd/neofs-node/config.go b/cmd/neofs-node/config.go
index bfe5a95942..2ebfbc9437 100644
--- a/cmd/neofs-node/config.go
+++ b/cmd/neofs-node/config.go
@@ -365,8 +365,8 @@ func defaultConfiguration(v *viper.Viper) {
 	v.SetDefault(cfgNodeKey, "Kwk6k2eC3L3QuPvD8aiaNyoSXgQ2YL1bwS5CP1oKoA9waeAze97s")
 	v.SetDefault(cfgBootstrapAddress, "") // address to bootstrap with
 
-	v.SetDefault(cfgMorphRPCAddress, "http://morph_chain.localtest.nspcc.ru:30333/")
-	v.SetDefault(cfgMorphNotifyRPCAddress, "ws://morph_chain:30333/ws")
+	v.SetDefault(cfgMorphRPCAddress, []string{})
+	v.SetDefault(cfgMorphNotifyRPCAddress, []string{})
 	v.SetDefault(cfgMorphNotifyDialTimeout, 5*time.Second)
 	v.SetDefault(cfgListenAddress, "127.0.0.1:50501") // listen address
 	v.SetDefault(cfgMaxMsgSize, 4<<20)                // transport msg limit 4 MiB
diff --git a/cmd/neofs-node/morph.go b/cmd/neofs-node/morph.go
index a346619758..a0197645de 100644
--- a/cmd/neofs-node/morph.go
+++ b/cmd/neofs-node/morph.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/util"
@@ -11,14 +12,44 @@ import (
 	"github.com/nspcc-dev/neofs-node/pkg/morph/event"
 	netmapEvent "github.com/nspcc-dev/neofs-node/pkg/morph/event/netmap"
 	"github.com/nspcc-dev/neofs-node/pkg/morph/subscriber"
+	"github.com/nspcc-dev/neofs-node/pkg/util/rand"
+	"go.uber.org/zap"
 )
 
 const newEpochNotification = "NewEpoch"
 
+var (
+	errNoRPCEndpoints = errors.New("NEO RPC endpoints are not specified in config")
+	errNoWSEndpoints  = errors.New("websocket NEO listener endpoints are not specified in config")
+)
+
 func initMorphComponents(c *cfg) {
 	var err error
 
-	c.cfgMorph.client, err = client.New(c.key, c.viper.GetString(cfgMorphRPCAddress))
+	addresses := c.viper.GetStringSlice(cfgMorphRPCAddress)
+	if len(addresses) == 0 {
+		fatalOnErr(errNoRPCEndpoints)
+	}
+
+	crand := rand.New() // math/rand with cryptographic source
+	crand.Shuffle(len(addresses), func(i, j int) {
+		addresses[i], addresses[j] = addresses[j], addresses[i]
+	})
+
+	for i := range addresses {
+		c.cfgMorph.client, err = client.New(c.key, addresses[i])
+		if err == nil {
+			c.log.Info("neo RPC connection established",
+				zap.String("endpoint", addresses[i]))
+
+			break
+		}
+
+		c.log.Info("failed to establish neo RPC connection, trying another",
+			zap.String("endpoint", addresses[i]),
+			zap.String("error", err.Error()))
+	}
+
 	fatalOnErr(err)
 
 	staticClient, err := client.NewStatic(
@@ -39,11 +70,41 @@ func initMorphComponents(c *cfg) {
 }
 
 func listenMorphNotifications(c *cfg) {
-	subs, err := subscriber.New(c.ctx, &subscriber.Params{
-		Log:         c.log,
-		Endpoint:    c.viper.GetString(cfgMorphNotifyRPCAddress),
-		DialTimeout: c.viper.GetDuration(cfgMorphNotifyDialTimeout),
+	var (
+		err  error
+		subs subscriber.Subscriber
+	)
+
+	endpoints := c.viper.GetStringSlice(cfgMorphNotifyRPCAddress)
+	if len(endpoints) == 0 {
+		fatalOnErr(errNoWSEndpoints)
+	}
+
+	timeout := c.viper.GetDuration(cfgMorphNotifyDialTimeout)
+
+	crand := rand.New() // math/rand with cryptographic source
+	crand.Shuffle(len(endpoints), func(i, j int) {
+		endpoints[i], endpoints[j] = endpoints[j], endpoints[i]
 	})
+
+	for i := range endpoints {
+		subs, err = subscriber.New(c.ctx, &subscriber.Params{
+			Log:         c.log,
+			Endpoint:    endpoints[i],
+			DialTimeout: timeout,
+		})
+		if err == nil {
+			c.log.Info("websocket neo event listener established",
+				zap.String("endpoint", endpoints[i]))
+
+			break
+		}
+
+		c.log.Info("failed to establish websocket neo event listener, trying another",
+			zap.String("endpoint", endpoints[i]),
+			zap.String("error", err.Error()))
+	}
+
 	fatalOnErr(err)
 
 	lis, err := event.NewListener(event.ListenerParams{