Feat/http resovler (#953)

* add http resolver & balancer

Co-authored-by: chenzhihui <zhihui_chen@foxmail.com>

examples/helloworld/client/main.go

@@ -24,7 +24,7 @@ func callHTTP() {
 			recovery.Recovery(),
 		),
 		transhttp.WithEndpoint("127.0.0.1:8000"),
-		transhttp.WithSchema("http"),
+		transhttp.WithScheme("http"),
 	)
 	if err != nil {
 		log.Fatal(err)

examples/registry/consul/client/main.go

@@ -3,10 +3,13 @@ package main
 import (
 	"context"
 	"log"
+	"time"
 
 	"github.com/go-kratos/consul/registry"
 	"github.com/go-kratos/kratos/examples/helloworld/helloworld"
+	"github.com/go-kratos/kratos/v2/middleware/recovery"
 	"github.com/go-kratos/kratos/v2/transport/grpc"
+	transhttp "github.com/go-kratos/kratos/v2/transport/http"
 	"github.com/hashicorp/consul/api"
 )
 
@@ -15,6 +18,11 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
+	callHTTP(cli)
+	callGRPC(cli)
+}
+
+func callGRPC(cli *api.Client) {
 	r := registry.New(cli)
 	conn, err := grpc.DialInsecure(
 		context.Background(),
@@ -25,9 +33,33 @@ func main() {
 		log.Fatal(err)
 	}
 	client := helloworld.NewGreeterClient(conn)
-	reply, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "kratos"})
+	reply, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "kratos_grpc"})
 	if err != nil {
 		log.Fatal(err)
 	}
 	log.Printf("[grpc] SayHello %+v\n", reply)
 }
+
+func callHTTP(cli *api.Client) {
+	r := registry.New(cli)
+	conn, err := transhttp.NewClient(
+		context.Background(),
+		transhttp.WithMiddleware(
+			recovery.Recovery(),
+		),
+		transhttp.WithScheme("http"),
+		transhttp.WithEndpoint("discovery:///helloworld"),
+		transhttp.WithDiscovery(r),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	time.Sleep(time.Millisecond * 250)
+	client := helloworld.NewGreeterHttpClient(conn)
+	reply, err := client.SayHello(context.Background(), &helloworld.HelloRequest{Name: "kratos_http"})
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("[http] SayHello %s\n", reply.Message)
+
+}

examples/registry/consul/server/main.go

@@ -3,12 +3,16 @@ package main
 import (
 	"context"
 	"fmt"
-	"log"
+	"os"
 
 	"github.com/go-kratos/consul/registry"
 	pb "github.com/go-kratos/kratos/examples/helloworld/helloworld"
 	"github.com/go-kratos/kratos/v2"
+	"github.com/go-kratos/kratos/v2/log"
+	"github.com/go-kratos/kratos/v2/middleware/logging"
+	"github.com/go-kratos/kratos/v2/middleware/recovery"
 	"github.com/go-kratos/kratos/v2/transport/grpc"
+	"github.com/go-kratos/kratos/v2/transport/http"
 	"github.com/hashicorp/consul/api"
 )
 
@@ -23,27 +27,41 @@ func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloRe
 }
 
 func main() {
+	logger := log.NewStdLogger(os.Stdout)
+	log := log.NewHelper(logger)
+	consulClient, err := api.NewClient(api.DefaultConfig())
+	if err != nil {
+		panic(err)
+	}
+
 	grpcSrv := grpc.NewServer(
 		grpc.Address(":9000"),
+		grpc.Middleware(
+			recovery.Recovery(),
+			logging.Server(logger),
+		),
 	)
-
 	s := &server{}
 	pb.RegisterGreeterServer(grpcSrv, s)
 
-	cli, err := api.NewClient(api.DefaultConfig())
-	if err != nil {
-		panic(err)
-	}
-	r := registry.New(cli)
+	httpSrv := http.NewServer(http.Address(":8000"))
+	httpSrv.HandlePrefix("/", pb.NewGreeterHandler(s,
+		http.Middleware(
+			recovery.Recovery(),
+		)),
+	)
+
+	r := registry.New(consulClient)
 	app := kratos.New(
 		kratos.Name("helloworld"),
 		kratos.Server(
 			grpcSrv,
+			httpSrv,
 		),
 		kratos.Registrar(r),
 	)
 
 	if err := app.Run(); err != nil {
-		log.Fatal(err)
+		log.Errorf("app run failed:%v", err)
 	}
 }

internal/balancer/balancer.go

@@ -0,0 +1,18 @@
+package balancer
+
+import (
+	"context"
+
+	"github.com/go-kratos/kratos/v2/registry"
+)
+
+// DoneInfo is callback when rpc done
+type DoneInfo struct {
+	Err     error
+	Trailer map[string]string
+}
+
+// Balancer is node pick balancer
+type Balancer interface {
+	Pick(ctx context.Context, pathPattern string, nodes []*registry.ServiceInstance) (node *registry.ServiceInstance, done func(DoneInfo), err error)
+}

internal/balancer/random/random.go

@@ -0,0 +1,29 @@
+package random
+
+import (
+	"context"
+	"fmt"
+	"math/rand"
+
+	"github.com/go-kratos/kratos/v2/internal/balancer"
+	"github.com/go-kratos/kratos/v2/registry"
+)
+
+var _ balancer.Balancer = &Balancer{}
+
+type Balancer struct {
+}
+
+func New() *Balancer {
+	return &Balancer{}
+}
+
+func (b *Balancer) Pick(ctx context.Context, pathPattern string, nodes []*registry.ServiceInstance) (node *registry.ServiceInstance, done func(balancer.DoneInfo), err error) {
+	if len(nodes) == 0 {
+		return nil, nil, fmt.Errorf("no instances avaiable")
+	} else if len(nodes) == 1 {
+		return nodes[0], func(di balancer.DoneInfo) {}, nil
+	}
+	idx := rand.Intn(len(nodes))
+	return nodes[idx], func(di balancer.DoneInfo) {}, nil
+}

transport/http/client.go

@@ -7,28 +7,40 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 	"time"
 
 	"github.com/go-kratos/kratos/v2/encoding"
 	"github.com/go-kratos/kratos/v2/errors"
+	"github.com/go-kratos/kratos/v2/internal/balancer"
+	"github.com/go-kratos/kratos/v2/internal/balancer/random"
 	"github.com/go-kratos/kratos/v2/internal/httputil"
 	"github.com/go-kratos/kratos/v2/middleware"
+	"github.com/go-kratos/kratos/v2/registry"
 	"github.com/go-kratos/kratos/v2/transport"
 )
 
 // Client is http client
 type Client struct {
 	cc *http.Client
+	r  *resolver
+	b  balancer.Balancer
 
-	schema       string
-	endpoint     string
+	scheme       string
+	target       Target
 	userAgent    string
 	middleware   middleware.Middleware
 	encoder      EncodeRequestFunc
 	decoder      DecodeResponseFunc
 	errorDecoder DecodeErrorFunc
+	discovery    registry.Discovery
 }
 
+const (
+	// errNodeNotFound represents service node not found.
+	errNodeNotFound = "NODE_NOT_FOUND"
+)
+
 // DecodeErrorFunc is decode error func.
 type DecodeErrorFunc func(ctx context.Context, res *http.Response) error
 
@@ -69,10 +81,10 @@ func WithMiddleware(m ...middleware.Middleware) ClientOption {
 	}
 }
 
-// WithSchema with client schema.
-func WithSchema(schema string) ClientOption {
+// WithScheme with client schema.
+func WithScheme(scheme string) ClientOption {
 	return func(o *clientOptions) {
-		o.schema = schema
+		o.scheme = scheme
 	}
 }
 
@@ -104,43 +116,94 @@ func WithErrorDecoder(errorDecoder DecodeErrorFunc) ClientOption {
 	}
 }
 
+// WithDiscovery with client discovery.
+func WithDiscovery(d registry.Discovery) ClientOption {
+	return func(o *clientOptions) {
+		o.discovery = d
+	}
+}
+
+// WithBalancer with client balancer.
+// Experimental
+// Notice: This type is EXPERIMENTAL and may be changed or removed in a later release.
+func WithBalancer(b balancer.Balancer) ClientOption {
+	return func(o *clientOptions) {
+		o.balancer = b
+	}
+}
+
 // Client is a HTTP transport client.
 type clientOptions struct {
 	ctx          context.Context
 	transport    http.RoundTripper
 	middleware   middleware.Middleware
 	timeout      time.Duration
-	schema       string
+	scheme       string
 	endpoint     string
 	userAgent    string
 	encoder      EncodeRequestFunc
 	decoder      DecodeResponseFunc
 	errorDecoder DecodeErrorFunc
+	discovery    registry.Discovery
+	balancer     balancer.Balancer
 }
 
 // NewClient returns an HTTP client.
 func NewClient(ctx context.Context, opts ...ClientOption) (*Client, error) {
 	options := &clientOptions{
 		ctx:          ctx,
-		schema:       "http",
+		scheme:       "http",
 		timeout:      1 * time.Second,
 		encoder:      defaultRequestEncoder,
 		decoder:      defaultResponseDecoder,
 		errorDecoder: defaultErrorDecoder,
 		transport:    http.DefaultTransport,
+		discovery:    nil,
+		balancer:     random.New(),
 	}
 	for _, o := range opts {
 		o(options)
 	}
+	target := Target{
+		Scheme:   options.scheme,
+		Endpoint: options.endpoint,
+	}
+	var r *resolver
+	if options.endpoint != "" && options.discovery != nil {
+		u, err := url.Parse(options.endpoint)
+		if err != nil {
+			u, err = url.Parse("http://" + options.endpoint)
+			if err != nil {
+				return nil, fmt.Errorf("[http client] invalid endpoint format: %v", options.endpoint)
+			}
+		}
+		if u.Scheme == "discovery" && len(u.Path) > 1 {
+			target = Target{
+				Scheme:    u.Scheme,
+				Authority: u.Host,
+				Endpoint:  u.Path[1:],
+			}
+			r, err = newResolver(ctx, options.scheme, options.discovery, target)
+			if err != nil {
+				return nil, fmt.Errorf("[http client] new resolver failed!err: %v", options.endpoint)
+			}
+		} else {
+			return nil, fmt.Errorf("[http client] invalid endpoint format: %v", options.endpoint)
+		}
+	}
+
 	return &Client{
 		cc:           &http.Client{Timeout: options.timeout, Transport: options.transport},
+		r:            r,
 		encoder:      options.encoder,
 		decoder:      options.decoder,
 		errorDecoder: options.errorDecoder,
 		middleware:   options.middleware,
 		userAgent:    options.userAgent,
-		endpoint:     options.endpoint,
-		schema:       options.schema,
+		target:       target,
+		scheme:       options.scheme,
+		discovery:    options.discovery,
+		b:            options.balancer,
 	}, nil
 }
 
@@ -169,7 +232,7 @@ func (client *Client) Invoke(ctx context.Context, path string, args interface{},
 		}
 		reqBody = bytes.NewReader(body)
 	}
-	url := fmt.Sprintf("%s://%s%s", client.schema, client.endpoint, path)
+	url := fmt.Sprintf("%s://%s%s", client.scheme, client.target.Endpoint, path)
 	req, err := http.NewRequest(c.method, url, reqBody)
 	if err != nil {
 		return err
@@ -192,7 +255,29 @@ func (client *Client) Invoke(ctx context.Context, path string, args interface{},
 
 func (client *Client) invoke(ctx context.Context, req *http.Request, args interface{}, reply interface{}, c callInfo) error {
 	h := func(ctx context.Context, in interface{}) (interface{}, error) {
+		var done func(balancer.DoneInfo)
+		if client.r != nil {
+			nodes := client.r.fetch(ctx)
+			if len(nodes) == 0 {
+				return nil, errors.ServiceUnavailable(errNodeNotFound, "fetch error")
+			}
+			var node *registry.ServiceInstance
+			var err error
+			node, done, err = client.b.Pick(ctx, c.pathPattern, nodes)
+			if err != nil {
+				return nil, errors.ServiceUnavailable(errNodeNotFound, err.Error())
+			}
+			req = req.Clone(ctx)
+			addr, err := parseEndpoint(client.scheme, node.Endpoints)
+			if err != nil {
+				return nil, errors.ServiceUnavailable(errNodeNotFound, err.Error())
+			}
+			req.URL.Host = addr
+		}
 		res, err := client.do(ctx, req, c)
+		if done != nil {
+			done(balancer.DoneInfo{Err: err})
+		}
 		if err != nil {
 			return nil, err
 		}

transport/http/resovler.go

@@ -0,0 +1,86 @@
+package http
+
+import (
+	"context"
+	"net/url"
+	"sync"
+
+	"github.com/go-kratos/kratos/v2/log"
+	"github.com/go-kratos/kratos/v2/registry"
+)
+
+// Target is resolver target
+type Target struct {
+	Scheme    string
+	Authority string
+	Endpoint  string
+}
+
+type resolver struct {
+	lock  sync.RWMutex
+	nodes []*registry.ServiceInstance
+
+	target  Target
+	watcher registry.Watcher
+	logger  *log.Helper
+}
+
+func newResolver(ctx context.Context, scheme string, discovery registry.Discovery, target Target) (*resolver, error) {
+	watcher, err := discovery.Watch(ctx, target.Endpoint)
+	if err != nil {
+		return nil, err
+	}
+	r := &resolver{
+		target:  target,
+		watcher: watcher,
+		logger:  log.NewHelper(log.DefaultLogger),
+	}
+	go func() {
+		for {
+			services, err := watcher.Next()
+			if err != nil {
+				r.logger.Errorf("http client watch services got unexpected error:=%v", err)
+				return
+			}
+			var nodes []*registry.ServiceInstance
+			for _, in := range services {
+				endpoint, err := parseEndpoint(scheme, in.Endpoints)
+				if err != nil {
+					r.logger.Errorf("Failed to parse discovery endpoint: %v error %v", in.Endpoints, err)
+					continue
+				}
+				if endpoint == "" {
+					continue
+				}
+				nodes = append(nodes, in)
+			}
+			if len(nodes) != 0 {
+				r.lock.Lock()
+				r.nodes = nodes
+				r.lock.Unlock()
+			}
+		}
+	}()
+	return r, nil
+}
+
+func (r *resolver) fetch(ctx context.Context) []*registry.ServiceInstance {
+	r.lock.RLock()
+	nodes := r.nodes
+	r.lock.RUnlock()
+
+	return nodes
+}
+
+func parseEndpoint(schema string, endpoints []string) (string, error) {
+	for _, e := range endpoints {
+		u, err := url.Parse(e)
+		if err != nil {
+			return "", err
+		}
+		if u.Scheme == schema {
+			return u.Host, nil
+		}
+	}
+	return "", nil
+}