feature: retry() filter

feature: net.Client.Retry()

Signed-off-by: Sandor Szücs <sandor.szuecs@zalando.de>

filters/builtin/builtin.go

@@ -15,6 +15,7 @@ import (
 	"github.com/zalando/skipper/filters/fadein"
 	"github.com/zalando/skipper/filters/flowid"
 	logfilter "github.com/zalando/skipper/filters/log"
+	"github.com/zalando/skipper/filters/retry"
 	"github.com/zalando/skipper/filters/rfc"
 	"github.com/zalando/skipper/filters/scheduler"
 	"github.com/zalando/skipper/filters/sed"
@@ -229,6 +230,7 @@ func Filters() []filters.Spec {
 		fadein.NewEndpointCreated(),
 		consistenthash.NewConsistentHashKey(),
 		consistenthash.NewConsistentHashBalanceFactor(),
+		retry.NewRetry(),
 		tls.New(),
 	}
 }

filters/filters.go

@@ -333,6 +333,7 @@ const (
 	FifoWithBodyName                           = "fifoWithBody"
 	LifoName                                   = "lifo"
 	LifoGroupName                              = "lifoGroup"
+	RetryName                                  = "retry"
 	RfcPathName                                = "rfcPath"
 	RfcHostName                                = "rfcHost"
 	BearerInjectorName                         = "bearerinjector"

filters/retry/retry.go

@@ -0,0 +1,18 @@
+package retry
+
+import (
+	"github.com/zalando/skipper/filters"
+)
+
+type retry struct{}
+
+// NewRetry creates a filter specification for the retry() filter
+func NewRetry() filters.Spec { return retry{} }
+
+func (retry) Name() string                                       { return filters.RetryName }
+func (retry) CreateFilter([]interface{}) (filters.Filter, error) { return retry{}, nil }
+func (retry) Response(filters.FilterContext)                     {}
+
+func (retry) Request(ctx filters.FilterContext) {
+	ctx.StateBag()[filters.RetryName] = struct{}{}
+}

filters/retry/retry_test.go

@@ -0,0 +1,95 @@
+package retry
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/AlexanderYastrebov/noleak"
+	"github.com/zalando/skipper/eskip"
+	"github.com/zalando/skipper/filters"
+	"github.com/zalando/skipper/proxy/proxytest"
+)
+
+func TestRetry(t *testing.T) {
+	for _, tt := range []struct {
+		name   string
+		method string
+		body   string
+	}{
+		{
+			name:   "test GET",
+			method: "GET",
+		},
+		{
+			name:   "test POST",
+			method: "POST",
+			body:   "hello POST",
+		},
+		{
+			name:   "test PATCH",
+			method: "PATCH",
+			body:   "hello PATCH",
+		},
+		{
+			name:   "test PUT",
+			method: "PUT",
+			body:   "hello PUT",
+		}} {
+		t.Run(tt.name, func(t *testing.T) {
+			i := 0
+			backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if i == 0 {
+					i++
+					w.WriteHeader(http.StatusBadGateway)
+					return
+				}
+
+				got, err := io.ReadAll(r.Body)
+				if err != nil {
+					t.Fatalf("got no data")
+				}
+				s := string(got)
+				if tt.body != s {
+					t.Fatalf("Failed to get the right data want: %q, got: %q", tt.body, s)
+				}
+
+				w.WriteHeader(http.StatusOK)
+			}))
+			defer backend.Close()
+
+			noleak.Check(t)
+
+			fr := make(filters.Registry)
+			retry := NewRetry()
+			fr.Register(retry)
+			r := &eskip.Route{
+				Filters: []*eskip.Filter{
+					{Name: retry.Name()},
+				},
+				Backend: backend.URL,
+			}
+
+			proxy := proxytest.New(fr, r)
+			defer proxy.Close()
+
+			buf := bytes.NewBufferString(tt.body)
+			req, err := http.NewRequest(tt.method, proxy.URL, buf)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			rsp, err := http.DefaultClient.Do(req)
+			if err != nil {
+				t.Fatalf("Failed to execute retry: %v", err)
+			}
+
+			if rsp.StatusCode != http.StatusOK {
+				t.Fatalf("unexpected status code: %s", rsp.Status)
+			}
+			rsp.Body.Close()
+		})
+	}
+}

io/copy_stream.go

@@ -0,0 +1,48 @@
+package io
+
+import (
+	"bytes"
+	"io"
+)
+
+type bodyBuffer struct{ *bytes.Buffer }
+
+func (buf *bodyBuffer) Close() error {
+	return nil
+}
+
+type CopyBodyStream struct {
+	left  int
+	buf   *bodyBuffer
+	input io.ReadCloser
+}
+
+func NewCopyBodyStream(left int, buf *bytes.Buffer, rc io.ReadCloser) *CopyBodyStream {
+	return &CopyBodyStream{
+		left:  left,
+		buf:   &bodyBuffer{Buffer: buf},
+		input: rc,
+	}
+}
+
+func (cb *CopyBodyStream) Len() int {
+	return cb.buf.Len()
+}
+
+func (cb *CopyBodyStream) Read(p []byte) (n int, err error) {
+	n, err = cb.input.Read(p)
+	if cb.left > 0 && n > 0 {
+		m := min(n, cb.left)
+		cb.buf.Write(p[:m])
+		cb.left -= m
+	}
+	return n, err
+}
+
+func (cb *CopyBodyStream) Close() error {
+	return cb.input.Close()
+}
+
+func (cb *CopyBodyStream) GetBody() io.ReadCloser {
+	return cb.buf
+}

io/copy_stream_test.go

@@ -0,0 +1,41 @@
+package io
+
+import (
+	"bytes"
+	"io"
+	"testing"
+)
+
+type tbuf struct{ *bytes.Buffer }
+
+func (tb *tbuf) Read(p []byte) (int, error) {
+	return tb.Buffer.Read(p)
+}
+func (tb *tbuf) Close() error {
+	return nil
+}
+
+func TestCopyBodyStream(t *testing.T) {
+	s := "content"
+	bbuf := &tbuf{bytes.NewBufferString(s)}
+	cbs := NewCopyBodyStream(bbuf.Len(), &bytes.Buffer{}, bbuf)
+
+	buf := make([]byte, len(s))
+	cbs.Read(buf)
+
+	if cbs.Len() != len(buf) {
+		t.Fatalf("Failed to have the same buf buffer size want: %d, got: %d", cbs.Len(), len(buf))
+	}
+
+	got, err := io.ReadAll(cbs.GetBody())
+	if err != nil {
+		t.Fatalf("Failed to read: %v", err)
+	}
+	if gotStr := string(got); s != gotStr {
+		t.Fatalf("Failed to get the right content: %s != %s", s, gotStr)
+	}
+
+	if err = cbs.Close(); err != nil {
+		t.Fatal(err)
+	}
+}

net/httpclient.go

@@ -3,6 +3,7 @@ package net
 import (
 	"bytes"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -15,6 +16,7 @@ import (
 
 	"github.com/opentracing/opentracing-go"
 	"github.com/opentracing/opentracing-go/ext"
+	skpio "github.com/zalando/skipper/io"
 	"github.com/zalando/skipper/logging"
 	"github.com/zalando/skipper/secrets"
 )
@@ -24,43 +26,7 @@ const (
 	defaultRefreshInterval = 5 * time.Minute
 )
 
-type mybuf struct{ *bytes.Buffer }
-
-func (buf *mybuf) Close() error {
-	return nil
-}
-
-type copyBodyStream struct {
-	left  int
-	buf   *mybuf
-	input io.ReadCloser
-}
-
-func newCopyBodyStream(left int, buf *bytes.Buffer, rc io.ReadCloser) *copyBodyStream {
-	return &copyBodyStream{
-		left:  left,
-		buf:   &mybuf{Buffer: buf},
-		input: rc,
-	}
-}
-
-func (cb *copyBodyStream) Read(p []byte) (n int, err error) {
-	n, err = cb.input.Read(p)
-	if cb.left > 0 && n > 0 {
-		m := min(n, cb.left)
-		cb.buf.Write(p[:m])
-		cb.left -= m
-	}
-	return n, err
-}
-
-func (cb *copyBodyStream) Close() error {
-	return cb.input.Close()
-}
-
-func (cb *copyBodyStream) GetBody() io.ReadCloser {
-	return cb.buf
-}
+var errRequestNotFound = errors.New("request not found")
 
 // Client adds additional features like Bearer token injection, and
 // opentracing to the wrapped http.Client with the same interface as
@@ -166,8 +132,8 @@ func (c *Client) Do(req *http.Request) (*http.Response, error) {
 			req.Header.Set("Authorization", "Bearer "+string(b))
 		}
 	}
-	if req.Body != nil && req.Body != http.NoBody {
-		retryBuffer := newCopyBodyStream(int(req.ContentLength), &bytes.Buffer{}, req.Body)
+	if req.Body != nil && req.Body != http.NoBody && req.ContentLength > 0 {
+		retryBuffer := skpio.NewCopyBodyStream(int(req.ContentLength), &bytes.Buffer{}, req.Body)
 		c.retryBuffers.Store(req, retryBuffer)
 		req.Body = retryBuffer
 	}
@@ -179,20 +145,20 @@ func (c *Client) Retry(req *http.Request) (*http.Response, error) {
 		return c.Do(req)
 	}
 
-	if rc, err := req.GetBody(); err == nil {
-		println("req.GetBody() case")
-		c.retryBuffers.Delete(req)
-		req.Body = rc
-		return c.Do(req)
-	}
+	// Next line panics on TestClientRetryBodyHalfReader
+	// if rc, err := req.GetBody(); err == nil {
+	// 	c.retryBuffers.Delete(req)
+	// 	req.Body = rc
+	// 	return c.Do(req)
+	// }
+	// return nil, fmt.Errorf("failed to retry")
 
-	println("our own retry buffer impl")
 	buf, ok := c.retryBuffers.Load(req)
 	if !ok {
-		return nil, fmt.Errorf("no retry possible, request not found: %s %s", req.Method, req.URL)
+		return nil, fmt.Errorf("no retry possible, %w: %s %s", errRequestNotFound, req.Method, req.URL)
 	}
 
-	retryBuffer, ok := buf.(*copyBodyStream)
+	retryBuffer, ok := buf.(*skpio.CopyBodyStream)
 	if !ok {
 		return nil, fmt.Errorf("no retry possible, no retry buffer for request: %s %s", req.Method, req.URL)
 	}