feat!: build log writer for container request (#2925)

* feat: build log writer for container request

* fix: single BuildLogWriter method for ImageBuildInfo interface

* fix: change BuildLogWriter default behavior

* fix: require in Test_BuildContainerFromDockerfileWithBuildLogWriter

container.go

@@ -77,7 +77,7 @@ type ImageBuildInfo interface {
 	GetDockerfile() string                          // the relative path to the Dockerfile, including the file itself
 	GetRepo() string                                // get repo label for image
 	GetTag() string                                 // get tag label for image
-	ShouldPrintBuildLog() bool                      // allow build log to be printed to stdout
+	BuildLogWriter() io.Writer                      // for output of build log, use io.Discard to disable the output
 	ShouldBuildImage() bool                         // return true if the image needs to be built
 	GetBuildArgs() map[string]*string               // return the environment args used to build the from Dockerfile
 	GetAuthConfigs() map[string]registry.AuthConfig // Deprecated. Testcontainers will detect registry credentials automatically. Return the auth configs to be able to pull from an authenticated docker registry
@@ -92,7 +92,8 @@ type FromDockerfile struct {
 	Repo           string                         // the repo label for image, defaults to UUID
 	Tag            string                         // the tag label for image, defaults to UUID
 	BuildArgs      map[string]*string             // enable user to pass build args to docker daemon
-	PrintBuildLog  bool                           // enable user to print build log
+	PrintBuildLog  bool                           // Deprecated: Use BuildLogWriter instead
+	BuildLogWriter io.Writer                      // for output of build log, defaults to io.Discard
 	AuthConfigs    map[string]registry.AuthConfig // Deprecated. Testcontainers will detect registry credentials automatically. Enable auth configs to be able to pull from an authenticated docker registry
 	// KeepImage describes whether DockerContainer.Terminate should not delete the
 	// container image. Useful for images that are built from a Dockerfile and take a
@@ -410,8 +411,20 @@ func (c *ContainerRequest) ShouldKeepBuiltImage() bool {
 	return c.FromDockerfile.KeepImage
 }
 
-func (c *ContainerRequest) ShouldPrintBuildLog() bool {
-	return c.FromDockerfile.PrintBuildLog
+// BuildLogWriter returns the io.Writer for output of log when building a Docker image from
+// a Dockerfile. It returns the BuildLogWriter from the ContainerRequest, defaults to io.Discard.
+// For backward compatibility, if BuildLogWriter is default and PrintBuildLog is true,
+// the function returns os.Stderr.
+func (c *ContainerRequest) BuildLogWriter() io.Writer {
+	if c.FromDockerfile.BuildLogWriter != nil {
+		return c.FromDockerfile.BuildLogWriter
+	}
+	if c.FromDockerfile.PrintBuildLog {
+		c.FromDockerfile.BuildLogWriter = os.Stderr
+	} else {
+		c.FromDockerfile.BuildLogWriter = io.Discard
+	}
+	return c.FromDockerfile.BuildLogWriter
 }
 
 // BuildOptions returns the image build options when building a Docker image from a Dockerfile.

docker.go

@@ -1004,10 +1004,7 @@ func (p *DockerProvider) BuildImage(ctx context.Context, img ImageBuildInfo) (st
 	}
 	defer resp.Body.Close()
 
-	output := io.Discard
-	if img.ShouldPrintBuildLog() {
-		output = os.Stderr
-	}
+	output := img.BuildLogWriter()
 
 	// Always process the output, even if it is not printed
 	// to ensure that errors during the build process are

docker_test.go

@@ -705,6 +705,37 @@ func Test_BuildContainerFromDockerfileWithBuildLog(t *testing.T) {
 	assert.Regexpf(t, `^Step\s*1/\d+\s*:\s*FROM alpine$`, temp[0], "Expected stdout first line to be %s. Got '%s'.", "Step 1/* : FROM alpine", temp[0])
 }
 
+func Test_BuildContainerFromDockerfileWithBuildLogWriter(t *testing.T) {
+	var buffer bytes.Buffer
+
+	ctx := context.Background()
+
+	// fromDockerfile {
+	req := ContainerRequest{
+		FromDockerfile: FromDockerfile{
+			Context:        filepath.Join(".", "testdata"),
+			Dockerfile:     "buildlog.Dockerfile",
+			BuildLogWriter: &buffer,
+		},
+	}
+	// }
+
+	genContainerReq := GenericContainerRequest{
+		ProviderType:     providerType,
+		ContainerRequest: req,
+		Started:          true,
+	}
+
+	c, err := GenericContainer(ctx, genContainerReq)
+	CleanupContainer(t, c)
+	require.NoError(t, err)
+
+	out := buffer.String()
+	temp := strings.Split(out, "\n")
+	require.NotEmpty(t, temp)
+	require.Regexpf(t, `^Step\s*1/\d+\s*:\s*FROM alpine$`, temp[0], "Expected stdout first line to be %s. Got '%s'.", "Step 1/* : FROM alpine", temp[0])
+}
+
 func TestContainerCreationWaitsForLogAndPortContextTimeout(t *testing.T) {
 	ctx := context.Background()
 	req := ContainerRequest{