Merge pull request #4270 from nalind/skip-unused-stages-1.27

[release-1.27] build: support `--skip-unused-stages` for multi-stage builds.

define/build.go

@@ -186,6 +186,10 @@ type BuildOptions struct {
 	// specified, indicating that the shared, system-wide default policy
 	// should be used.
 	SignaturePolicyPath string
+	// SkipUnusedStages allows users to skip stages in a multi-stage builds
+	// which do not contribute anything to the target stage. Expected default
+	// value is true.
+	SkipUnusedStages types.OptionalBool
 	// ReportWriter is an io.Writer which will be used to report the
 	// progress of the (possible) pulling of the source image and the
 	// writing of the new image.

docs/buildah-build.1.md

@@ -669,6 +669,10 @@ If you omit the unit, the system uses bytes. If you omit the size entirely, the
 
 Sign the built image using the GPG key that matches the specified fingerprint.
 
+**--skip-unused-stages** *bool-value*
+
+Skip stages in multi-stage builds which don't affect the target stage. (Default is `true`).
+
 **--squash**
 
 Squash all of the image's new layers into a single new layer; any preexisting layers

imagebuildah/executor.go

@@ -82,6 +82,7 @@ type Executor struct {
 	out                            io.Writer
 	err                            io.Writer
 	signaturePolicyPath            string
+	skipUnusedStages               types.OptionalBool
 	systemContext                  *types.SystemContext
 	reportWriter                   io.Writer
 	isolation                      define.Isolation
@@ -237,6 +238,7 @@ func newExecutor(logger *logrus.Logger, logPrefix string, store storage.Store, o
 		outputFormat:                   options.OutputFormat,
 		additionalTags:                 options.AdditionalTags,
 		signaturePolicyPath:            options.SignaturePolicyPath,
+		skipUnusedStages:               options.SkipUnusedStages,
 		systemContext:                  options.SystemContext,
 		log:                            options.Log,
 		in:                             options.In,
@@ -792,9 +794,10 @@ func (b *Executor) Build(ctx context.Context, stages imagebuilder.Stages) (image
 					return
 				}
 				// Skip stage if it is not needed by TargetStage
-				// or any of its dependency stages.
+				// or any of its dependency stages and `SkipUnusedStages`
+				// is not set to `false`.
 				if stageDependencyInfo, ok := dependencyMap[stages[index].Name]; ok {
-					if !stageDependencyInfo.NeededByTarget {
+					if !stageDependencyInfo.NeededByTarget && b.skipUnusedStages != types.OptionalBoolFalse {
 						logrus.Debugf("Skipping stage with Name %q and index %d since its not needed by the target stage", stages[index].Name, index)
 						ch <- Result{
 							Index: index,

pkg/cli/build.go

@@ -20,6 +20,7 @@ import (
 	"github.com/containers/buildah/pkg/util"
 	"github.com/containers/common/pkg/auth"
 	"github.com/containers/image/v5/docker/reference"
+	"github.com/containers/image/v5/types"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 )
@@ -370,6 +371,7 @@ func GenBuildOptions(c *cobra.Command, inputArgs []string, iopts BuildOptions) (
 		RusageLogFile:           iopts.RusageLogFile,
 		SignBy:                  iopts.SignBy,
 		SignaturePolicyPath:     iopts.SignaturePolicy,
+		SkipUnusedStages:        types.NewOptionalBool(iopts.SkipUnusedStages),
 		Squash:                  iopts.Squash,
 		SystemContext:           systemContext,
 		Target:                  iopts.Target,

pkg/cli/common.go

@@ -89,6 +89,7 @@ type BudResults struct {
 	SignaturePolicy     string
 	SignBy              string
 	Squash              bool
+	SkipUnusedStages    bool
 	Stdin               bool
 	Tag                 []string
 	BuildOutput         string
@@ -258,6 +259,7 @@ func GetBudFlags(flags *BudResults) pflag.FlagSet {
 	if err := fs.MarkHidden("signature-policy"); err != nil {
 		panic(fmt.Sprintf("error marking the signature-policy flag as hidden: %v", err))
 	}
+	fs.BoolVar(&flags.SkipUnusedStages, "skip-unused-stages", true, "skips stages in multi-stage builds which do not affect the final target")
 	fs.BoolVar(&flags.Squash, "squash", false, "squash newly built layers into a single new layer")
 	fs.StringArrayVar(&flags.SSH, "ssh", []string{}, "SSH agent socket or keys to expose to the build. (format: default|<id>[=<socket>|<key>[,<key>]])")
 	fs.BoolVar(&flags.Stdin, "stdin", false, "pass stdin into containers")

tests/bud.bats

@@ -382,6 +382,38 @@ _EOF
   expect_output --substring "Groups:	1000"
 }
 
+@test "build-test skipping unwanted stages with --skip-unused-stages=false and --skip-unused-stages=true" {
+  mkdir -p ${TEST_SCRATCH_DIR}/bud/platform
+
+  cat > ${TEST_SCRATCH_DIR}/bud/platform/Dockerfile << _EOF
+FROM alpine
+RUN echo "first unwanted stage"
+
+FROM alpine as one
+RUN echo "needed stage"
+
+FROM alpine
+RUN echo "another unwanted stage"
+
+FROM one
+RUN echo "target stage"
+_EOF
+
+  # with --skip-unused-stages=false
+  run_buildah build $WITH_POLICY_JSON --skip-unused-stages=false -t source -f ${TEST_SCRATCH_DIR}/bud/platform/Dockerfile
+  expect_output --substring "needed stage"
+  expect_output --substring "target stage"
+  # this is expected since user specified `--skip-unused-stages=false`
+  expect_output --substring "first unwanted stage"
+  expect_output --substring "another unwanted stage"
+
+  # with --skip-unused-stages=true
+  run_buildah build $WITH_POLICY_JSON --skip-unused-stages=true -t source -f ${TEST_SCRATCH_DIR}/bud/platform/Dockerfile
+  expect_output --substring "needed stage"
+  expect_output --substring "target stage"
+  assert "$output" !~ "unwanted stage"
+}
+
 # Test skipping images with FROM
 @test "build-test skipping unwanted stages with FROM" {
   mkdir -p ${TEST_SCRATCH_DIR}/bud/platform