Use request context instead of background

This prevents goroutine leak:
If background context were used then push operation would continue even
if client aborted request by closing connection.

[NO TESTS NEEDED]

Signed-off-by: Matej Vasek <mvasek@redhat.com>

pkg/api/handlers/compat/images_push.go

@@ -1,7 +1,6 @@
 package compat
 
 import (
-	"context"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -12,7 +11,6 @@ import (
 	"github.com/containers/podman/v3/libpod"
 	"github.com/containers/podman/v3/pkg/api/handlers/utils"
 	"github.com/containers/podman/v3/pkg/auth"
-	"github.com/containers/podman/v3/pkg/channel"
 	"github.com/containers/podman/v3/pkg/domain/entities"
 	"github.com/containers/podman/v3/pkg/domain/infra/abi"
 	"github.com/containers/storage"
@@ -101,46 +99,33 @@ func PushImage(w http.ResponseWriter, r *http.Request) {
 		destination = imageName
 	}
 
-	errorWriter := channel.NewWriter(make(chan []byte))
+	flush := func() {}
-	defer errorWriter.Close()
-
-	statusWriter := channel.NewWriter(make(chan []byte))
-	defer statusWriter.Close()
-
-	runCtx, cancel := context.WithCancel(context.Background())
-	var failed bool
-
-	go func() {
-		defer cancel()
-
-		statusWriter.Write([]byte(fmt.Sprintf("The push refers to repository [%s]", imageName)))
-
-		err := imageEngine.Push(runCtx, imageName, destination, options)
-		if err != nil {
-			if errors.Cause(err) != storage.ErrImageUnknown {
-				errorWriter.Write([]byte("An image does not exist locally with the tag: " + imageName))
-			} else {
-				errorWriter.Write([]byte(err.Error()))
-			}
-		}
-	}()
-
-	flush := func() {
 	if flusher, ok := w.(http.Flusher); ok {
-			flusher.Flush()
+		flush = flusher.Flush
-		}
 	}
 
 	w.WriteHeader(http.StatusOK)
 	w.Header().Add("Content-Type", "application/json")
 	flush()
 
+	var report jsonmessage.JSONMessage
 	enc := json.NewEncoder(w)
 	enc.SetEscapeHTML(true)
 
+	report.Status = fmt.Sprintf("The push refers to repository [%s]", imageName)
+	if err := enc.Encode(report); err != nil {
+		logrus.Warnf("Failed to json encode error %q", err.Error())
+	}
+	flush()
+
+	pushErrChan := make(chan error)
+	go func() {
+		pushErrChan <- imageEngine.Push(r.Context(), imageName, destination, options)
+	}()
+
 loop: // break out of for/select infinite loop
 	for {
-		var report jsonmessage.JSONMessage
+		report = jsonmessage.JSONMessage{}
 
 		select {
 		case e := <-options.Progress:
@@ -160,29 +145,40 @@ loop: // break out of for/select infinite loop
 			}
 			report.ID = e.Artifact.Digest.Encoded()[0:12]
 			if err := enc.Encode(report); err != nil {
-				errorWriter.Write([]byte(err.Error()))
+				logrus.Warnf("Failed to json encode error %q", err.Error())
 			}
 			flush()
-		case e := <-statusWriter.Chan():
+		case err := <-pushErrChan:
-			report.Status = string(e)
+			if err != nil {
-			if err := enc.Encode(report); err != nil {
+				var msg string
-				errorWriter.Write([]byte(err.Error()))
+				if errors.Cause(err) != storage.ErrImageUnknown {
+					msg = "An image does not exist locally with the tag: " + imageName
+				} else {
+					msg = err.Error()
 				}
-			flush()
-		case e := <-errorWriter.Chan():
-			failed = true
 				report.Error = &jsonmessage.JSONError{
-				Message: string(e),
+					Message: msg,
 				}
-			report.ErrorMessage = string(e)
+				report.ErrorMessage = msg
 				if err := enc.Encode(report); err != nil {
 					logrus.Warnf("Failed to json encode error %q", err.Error())
 				}
 				flush()
-		case <-runCtx.Done():
+				break loop
-			if !failed {
+			}
+
 			digestBytes, err := ioutil.ReadAll(digestFile)
-				if err == nil {
+			if err != nil {
+				report.Error = &jsonmessage.JSONError{
+					Message: err.Error(),
+				}
+				report.ErrorMessage = err.Error()
+				if err := enc.Encode(report); err != nil {
+					logrus.Warnf("Failed to json encode error %q", err.Error())
+				}
+				flush()
+				break loop
+			}
 			tag := query.Tag
 			if tag == "" {
 				tag = "latest"
@@ -191,12 +187,8 @@ loop: // break out of for/select infinite loop
 			if err := enc.Encode(report); err != nil {
 				logrus.Warnf("Failed to json encode error %q", err.Error())
 			}
+
 			flush()
-				}
-			}
-			break loop // break out of for/select infinite loop
-		case <-r.Context().Done():
-			// Client has closed connection
 			break loop // break out of for/select infinite loop
 		}
 	}