Least load balancer (#2999)

* v5: Health Check & LeastLoad Strategy (rebased from 2c5a71490368500a982018a74a6d519c7e121816)

Some changes will be necessary to integrate it into V2Ray

* Update proto

* parse duration conf with time.Parse()

* moving health ping to observatory as a standalone component

* moving health ping to observatory as a standalone component: auto generated file

* add initialization for health ping

* incorporate changes in router implementation

* support principle target output

* add v4 json support for BurstObservatory & fix balancer reference

* update API command

* remove cancelled API

* return zero length value when observer is not found

* remove duplicated targeted dispatch

* adjust test with updated structure

* bug fix for observer

* fix strategy selector

* fix strategy least load

* Fix ticker usage

ticker.Close does not close ticker.C

* feat: Replace default Health Ping URL to HTTPS (#1991)

* fix selectLeastLoad() returns wrong number of nodes (#2083)

* Test: fix leastload strategy unit test

* fix(router): panic caused by concurrent map read and write (#2678)

* Clean up code

---------

Co-authored-by: Jebbs <qjebbs@gmail.com>
Co-authored-by: Shelikhoo <xiaokangwang@outlook.com>
Co-authored-by: 世界 <i@sekai.icu>
Co-authored-by: Bernd Eichelberger <46166740+4-FLOSS-Free-Libre-Open-Source-Software@users.noreply.github.com>
Co-authored-by: 秋のかえで <autmaple@protonmail.com>
Co-authored-by: Rinka <kujourinka@gmail.com>

main/commands/all/api/api.go

@@ -15,6 +15,8 @@ var CmdAPI = &base.Command{
 		cmdGetStats,
 		cmdQueryStats,
 		cmdSysStats,
+		cmdBalancerInfo,
+		cmdBalancerOverride,
 		cmdAddInbounds,
 		cmdAddOutbounds,
 		cmdRemoveInbounds,

main/commands/all/api/balancer_info.go

@@ -0,0 +1,108 @@
+package api
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	routerService "github.com/xtls/xray-core/app/router/command"
+	"github.com/xtls/xray-core/main/commands/base"
+)
+
+// TODO: support "-json" flag for json output
+var cmdBalancerInfo = &base.Command{
+	CustomFlags: true,
+	UsageLine:   "{{.Exec}} api bi [--server=127.0.0.1:8080] [balancer]...",
+	Short:       "balancer information",
+	Long: `
+Get information of specified balancers, including health, strategy 
+and selecting. If no balancer tag specified, get information of 
+all balancers.
+
+> Make sure you have "RoutingService" set in "config.api.services" 
+of server config.
+
+Arguments:
+
+	-json
+		Use json output.
+
+	-s, -server <server:port>
+		The API server address. Default 127.0.0.1:8080
+
+	-t, -timeout <seconds>
+		Timeout seconds to call API. Default 3
+
+Example:
+
+    {{.Exec}} {{.LongName}} --server=127.0.0.1:8080 balancer1 balancer2
+`,
+	Run: executeBalancerInfo,
+}
+
+func executeBalancerInfo(cmd *base.Command, args []string) {
+	setSharedFlags(cmd)
+	cmd.Flag.Parse(args)
+
+	conn, ctx, close := dialAPIServer()
+	defer close()
+
+	client := routerService.NewRoutingServiceClient(conn)
+	r := &routerService.GetBalancerInfoRequest{Tag: args[0]}
+	resp, err := client.GetBalancerInfo(ctx, r)
+	if err != nil {
+		base.Fatalf("failed to get health information: %s", err)
+	}
+
+	if apiJSON {
+		showJSONResponse(resp)
+		return
+	}
+
+	showBalancerInfo(resp.Balancer)
+
+}
+
+func showBalancerInfo(b *routerService.BalancerMsg) {
+	const tableIndent = 4
+	sb := new(strings.Builder)
+	// Override
+	if b.Override != nil {
+		sb.WriteString("  - Selecting Override:\n")
+		for i, s := range []string{b.Override.Target} {
+			writeRow(sb, tableIndent, i+1, []string{s}, nil)
+		}
+	}
+	// Selects
+	sb.WriteString("  - Selects:\n")
+
+	for i, o := range b.PrincipleTarget.Tag {
+		writeRow(sb, tableIndent, i+1, []string{o}, nil)
+	}
+	os.Stdout.WriteString(sb.String())
+}
+
+func getColumnFormats(titles []string) []string {
+	w := make([]string, len(titles))
+	for i, t := range titles {
+		w[i] = fmt.Sprintf("%%-%ds ", len(t))
+	}
+	return w
+}
+
+func writeRow(sb *strings.Builder, indent, index int, values, formats []string) {
+	if index == 0 {
+		// title line
+		sb.WriteString(strings.Repeat(" ", indent+4))
+	} else {
+		sb.WriteString(fmt.Sprintf("%s%-4d", strings.Repeat(" ", indent), index))
+	}
+	for i, v := range values {
+		format := "%-14s"
+		if i < len(formats) {
+			format = formats[i]
+		}
+		sb.WriteString(fmt.Sprintf(format, v))
+	}
+	sb.WriteByte('\n')
+}

main/commands/all/api/balancer_override.go

@@ -0,0 +1,77 @@
+package api
+
+import (
+	routerService "github.com/xtls/xray-core/app/router/command"
+	"github.com/xtls/xray-core/main/commands/base"
+)
+
+var cmdBalancerOverride = &base.Command{
+	CustomFlags: true,
+	UsageLine:   "{{.Exec}} api bo [--server=127.0.0.1:8080] <-b balancer> outboundTag",
+	Short:       "balancer override",
+	Long: `
+Override a balancer's selection.
+
+> Make sure you have "RoutingService" set in "config.api.services" 
+of server config.
+
+Once a balancer's selecting is overridden:
+
+- The balancer's selection result will always be outboundTag
+
+Arguments:
+
+	-r, -remove
+		Remove the overridden
+
+	-r, -remove
+		Remove the override
+
+	-s, -server 
+		The API server address. Default 127.0.0.1:8080
+
+	-t, -timeout
+		Timeout seconds to call API. Default 3
+
+Example:
+
+    {{.Exec}} {{.LongName}} --server=127.0.0.1:8080 -b balancer tag
+    {{.Exec}} {{.LongName}} --server=127.0.0.1:8080 -b balancer -r
+`,
+	Run: executeBalancerOverride,
+}
+
+func executeBalancerOverride(cmd *base.Command, args []string) {
+	var (
+		balancer string
+		remove   bool
+	)
+	cmd.Flag.StringVar(&balancer, "b", "", "")
+	cmd.Flag.StringVar(&balancer, "balancer", "", "")
+	cmd.Flag.BoolVar(&remove, "r", false, "")
+	cmd.Flag.BoolVar(&remove, "remove", false, "")
+	setSharedFlags(cmd)
+	cmd.Flag.Parse(args)
+
+	if balancer == "" {
+		base.Fatalf("balancer tag not specified")
+	}
+
+	conn, ctx, close := dialAPIServer()
+	defer close()
+
+	client := routerService.NewRoutingServiceClient(conn)
+	target := ""
+	if !remove {
+		target = cmd.Flag.Args()[0]
+	}
+	r := &routerService.OverrideBalancerTargetRequest{
+		BalancerTag: balancer,
+		Target:      target,
+	}
+
+	_, err := client.OverrideBalancerTarget(ctx, r)
+	if err != nil {
+		base.Fatalf("failed to perform balancer health checks: %s", err)
+	}
+}

main/commands/all/api/shared.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"google.golang.org/protobuf/encoding/protojson"
 	"io"
 	"net/http"
 	"net/url"
@@ -15,7 +16,6 @@ import (
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/main/commands/base"
 	"google.golang.org/grpc"
-	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
 )
 
@@ -24,6 +24,7 @@ type serviceHandler func(ctx context.Context, conn *grpc.ClientConn, cmd *base.C
 var (
 	apiServerAddrPtr string
 	apiTimeout       int
+	apiJSON          bool
 )
 
 func setSharedFlags(cmd *base.Command) {
@@ -31,6 +32,7 @@ func setSharedFlags(cmd *base.Command) {
 	cmd.Flag.StringVar(&apiServerAddrPtr, "server", "127.0.0.1:8080", "")
 	cmd.Flag.IntVar(&apiTimeout, "t", 3, "")
 	cmd.Flag.IntVar(&apiTimeout, "timeout", 3, "")
+	cmd.Flag.BoolVar(&apiJSON, "json", false, "")
 }
 
 func dialAPIServer() (conn *grpc.ClientConn, ctx context.Context, close func()) {
@@ -103,13 +105,8 @@ func fetchHTTPContent(target string) ([]byte, error) {
 	return content, nil
 }
 
-func protoToJSONString(m proto.Message, _, indent string) (string, error) {
-	ops := protojson.MarshalOptions{
-		Indent:          indent,
-		EmitUnpopulated: true,
-	}
-	b, err := ops.Marshal(m)
-	return string(b), err
+func protoToJSONString(m proto.Message, prefix, indent string) (string, error) {
+	return strings.TrimSpace(protojson.MarshalOptions{Indent: indent}.Format(m)), nil
 }
 
 func showJSONResponse(m proto.Message) {