Swap to Reader in bake to avoid hangs on output

Signed-off-by: Nathan Scott <natedscott@gmail.com>

pkg/compose/build_bake.go

@@ -23,6 +23,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"math/rand"
 	"os"
 	"os/exec"
@@ -321,16 +322,22 @@ func (s *composeService) doBuildBake(ctx context.Context, project *types.Project
 	}
 
 	var errMessage []string
-	scanner := bufio.NewScanner(pipe)
+	reader := bufio.NewReader(pipe)
-	scanner.Split(bufio.ScanLines)
 
 	err = cmd.Start()
 	if err != nil {
 		return nil, err
 	}
 	eg.Go(cmd.Wait)
-	for scanner.Scan() {
+	for {
-		line := scanner.Text()
+		line, readErr := reader.ReadString('\n')
+		if readErr != nil {
+			if readErr == io.EOF {
+				break
+			} else {
+				return nil, fmt.Errorf("failed to execute bake: %w", readErr)
+			}
+		}
 		decoder := json.NewDecoder(strings.NewReader(line))
 		var status client.SolveStatus
 		err := decoder.Decode(&status)

pkg/e2e/build_test.go

@@ -580,3 +580,19 @@ func TestBuildSubDependencies(t *testing.T) {
 	out = res.Combined()
 	assert.Check(t, strings.Contains(out, "main  Built"))
 }
+
+func TestBuildLongOutputLine(t *testing.T) {
+	c := NewParallelCLI(t)
+
+	t.Cleanup(func() {
+		c.RunDockerComposeCmd(t, "-f", "fixtures/build-test/long-output-line/compose.yaml", "down", "--rmi=local")
+	})
+
+	res := c.RunDockerComposeCmd(t, "-f", "fixtures/build-test/long-output-line/compose.yaml", "build", "long-line")
+	out := res.Combined()
+	assert.Check(t, strings.Contains(out, "long-line  Built"))
+
+	res = c.RunDockerComposeCmd(t, "-f", "fixtures/build-test/long-output-line/compose.yaml", "up", "--build", "long-line")
+	out = res.Combined()
+	assert.Check(t, strings.Contains(out, "long-line  Built"))
+}

pkg/e2e/fixtures/build-test/long-output-line/Dockerfile

@@ -0,0 +1,49 @@
+#   Copyright 2020 Docker Compose CLI authors
+
+#   Licensed under the Apache License, Version 2.0 (the "License");
+#   you may not use this file except in compliance with the License.
+#   You may obtain a copy of the License at
+
+#       http://www.apache.org/licenses/LICENSE-2.0
+
+#   Unless required by applicable law or agreed to in writing, software
+#   distributed under the License is distributed on an "AS IS" BASIS,
+#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#   See the License for the specific language governing permissions and
+#   limitations under the License.
+FROM alpine
+# We generate warnings *on purpose* to bloat the JSON output of bake
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT
+ARG AWS_SECRET_ACCESS_KEY=FAKE_TO_GENERATE_WARNING_OUTPUT

pkg/e2e/fixtures/build-test/long-output-line/compose.yaml

@@ -0,0 +1,5 @@
+services:
+    long-line:
+      build:
+        context: .
+        dockerfile: Dockerfile