mz480: multitarget builds - part 1

README.md

@@ -1025,8 +1025,8 @@ want to save the image as tarball only you also need to set `--no-push`.
 
 #### Flag `--target`
 
-Set this flag to indicate which build stage is the target build stage.
-If not set we implicitly target the last stage.
+Set this flag to indicate which stages to build. If multiple targets are configured the first in the list is pushed.
+If not set we implicitly target the last stage of the Dockerfile.
 
 #### Flag `--use-new-run`
 

cmd/executor/cmd/root.go

@@ -271,7 +271,7 @@ func AddKanikoOptionsFlags(cmd *cobra.Command, opts *config.KanikoOptions) {
 	cmd.Flags().StringVarP(&opts.TarPath, "tar-path", "", "", "Path to save the image in as a tarball instead of pushing")
 	cmd.Flags().BoolVarP(&opts.SingleSnapshot, "single-snapshot", "", false, "Take a single snapshot at the end of the build.")
 	cmd.Flags().BoolVarP(&opts.Reproducible, "reproducible", "", false, "Strip timestamps out of the image to make it reproducible")
-	cmd.Flags().StringVarP(&opts.Target, "target", "", "", "Set the target build stage to build")
+	cmd.Flags().StringSliceVarP(&opts.Target, "target", "", []string{}, "Set the target stages to build, the first in the list denotes the stage to be pushed")
 	cmd.Flags().BoolVarP(&opts.NoPush, "no-push", "", false, "Do not push the image to the registry")
 	cmd.Flags().BoolVarP(&opts.NoPushCache, "no-push-cache", "", false, "Do not push the cache layers to the registry")
 	cmd.Flags().StringVarP(&opts.CacheRepo, "cache-repo", "", "", "Specify a repository to use as a cache, otherwise one will be inferred from the destination provided; when prefixed with 'oci:' the repository will be written in OCI image layout format at the path provided")

golden/golden_test.go

@@ -30,6 +30,7 @@ import (
 	testissuemz195 "github.com/osscontainertools/kaniko/golden/testdata/test_issue_mz195"
 	testissuemz333 "github.com/osscontainertools/kaniko/golden/testdata/test_issue_mz333"
 	testissuemz338 "github.com/osscontainertools/kaniko/golden/testdata/test_issue_mz338"
+	testissuemz480 "github.com/osscontainertools/kaniko/golden/testdata/test_issue_mz480"
 	testissuemz487 "github.com/osscontainertools/kaniko/golden/testdata/test_issue_mz487"
 	testunittests "github.com/osscontainertools/kaniko/golden/testdata/test_unittests"
 	"github.com/osscontainertools/kaniko/golden/types"
@@ -64,6 +65,7 @@ var allTests = map[string][]types.GoldenTests{
 	"test_issue_mz333": {testissuemz333.Tests},
 	"test_issue_mz338": {testissuemz338.Tests},
 	"test_issue_mz487": {testissuemz487.Tests},
+	"test_issue_mz480": {testissuemz480.Tests},
 	"test_unittests":   testunittests.Tests,
 }
 var update bool

golden/testdata/test_issue_mz480/Dockerfile

@@ -0,0 +1,11 @@
+FROM debian:12.10 AS base
+RUN install
+
+FROM base AS build
+RUN compile
+
+FROM base AS final
+COPY --from=build output output
+
+FROM final AS test
+RUN test

golden/testdata/test_issue_mz480/plans/final

@@ -0,0 +1,16 @@
+FROM debian:12.10 AS base
+UNPACK debian:12.10
+RUN install
+SAVE STAGE /kaniko/stages/0
+CLEAN
+
+FROM base AS build
+UNPACK /kaniko/stages/0
+RUN compile
+SAVE FILES [output] /kaniko/deps/1
+CLEAN
+
+FROM base AS final
+UNPACK /kaniko/stages/0
+COPY --from=build output output
+PUSH [registry]

golden/testdata/test_issue_mz480/plans/final_test

@@ -0,0 +1,22 @@
+FROM debian:12.10 AS base
+UNPACK debian:12.10
+RUN install
+SAVE STAGE /kaniko/stages/0
+CLEAN
+
+FROM base AS build
+UNPACK /kaniko/stages/0
+RUN compile
+SAVE FILES [output] /kaniko/deps/1
+CLEAN
+
+FROM base AS final
+UNPACK /kaniko/stages/0
+COPY --from=build output output
+PUSH [registry]
+SAVE STAGE /kaniko/stages/2
+CLEAN
+
+FROM final AS test
+UNPACK /kaniko/stages/2
+RUN test

golden/testdata/test_issue_mz480/test.go

@@ -0,0 +1,27 @@
+package testissuemz480
+
+import "github.com/osscontainertools/kaniko/golden/types"
+
+var Tests = types.GoldenTests{
+	Name:       "test_issue_mz480",
+	Dockerfile: "Dockerfile",
+	Tests: []types.GoldenTest{
+		{
+			Args: []string{"--target=final", "--destination=registry"},
+			// TODO: clean after "base" stage is unnecesary
+			Plan: "final",
+		},
+		{
+			Args: []string{"--target=final", "--target=build", "--destination=registry"},
+			// TODO: clean after "base" stage is unnecesary
+			Plan: "final",
+		},
+		{
+			Args: []string{"--target=final", "--target=test", "--destination=registry"},
+			// TODO: clean after "base" stage is unnecesary
+			// TODO: saving the "final" stage is unnecessary
+			// TODO: clean after "final" stage is unnecesary
+			Plan: "final_test",
+		},
+	},
+}

pkg/config/options.go

@@ -70,7 +70,7 @@ type KanikoOptions struct {
 	TarPath                      string
 	TarPathDeprecated            string
 	KanikoDir                    string
-	Target                       string
+	Target                       []string
 	CacheRepo                    string
 	DigestFile                   string
 	ImageNameDigestFile          string

pkg/config/stage.go

@@ -26,6 +26,7 @@ type KanikoStage struct {
 	BaseName               string
 	Commands               []instructions.Command
 	BaseImageIndex         int
+	Push                   bool
 	Final                  bool
 	BaseImageStoredLocally bool
 	SaveStage              bool

pkg/dockerfile/dockerfile.go

@@ -24,6 +24,7 @@ import (
 	"net/http"
 	"os"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 
@@ -197,17 +198,26 @@ func extractValFromQuotes(val string) (string, error) {
 	return val[1 : len(val)-1], nil
 }
 
-// targetStage returns the index of the target stage kaniko is trying to build
-func targetStage(stages []instructions.Stage, target string) (int, error) {
-	if target == "" {
-		return len(stages) - 1, nil
-	}
-	for i, stage := range stages {
-		if strings.EqualFold(stage.Name, target) {
-			return i, nil
+// targetStage returns the indexes of the target stages kaniko is trying to build
+func targetStages(stages []instructions.Stage, targets []string) ([]int, error) {
+	if len(targets) == 0 {
+		return []int{len(stages) - 1}, nil
+	}
+	var result []int
+	for _, target := range targets {
+		found := false
+		for i, stage := range stages {
+			if strings.EqualFold(stage.Name, target) {
+				result = append(result, i)
+				found = true
+				break
+			}
+		}
+		if !found {
+			return nil, fmt.Errorf("%q is not a valid target build stage", target)
 		}
 	}
-	return -1, fmt.Errorf("%s is not a valid target build stage", target)
+	return result, nil
 }
 
 // ParseCommands parses an array of commands into an array of instructions.Command; used for onbuild
@@ -262,15 +272,20 @@ func resolveStagesArgs(stages []instructions.Stage, args []string) error {
 }
 
 func MakeKanikoStages(opts *config.KanikoOptions, stages []instructions.Stage, metaArgs []instructions.ArgCommand) ([]config.KanikoStage, error) {
-	targetStage, err := targetStage(stages, opts.Target)
+	targetStages, err := targetStages(stages, opts.Target)
 	if err != nil {
 		return nil, fmt.Errorf("error finding target stage: %w", err)
 	}
+	pushStage := targetStages[0]
+	slices.Sort(targetStages)
+	targetStages = slices.Compact(targetStages)
+	finalStage := targetStages[len(targetStages)-1]
+
 	args := unifyArgs(metaArgs, opts.BuildArgs)
 	if err := resolveStagesArgs(stages, args); err != nil {
 		return nil, fmt.Errorf("resolving args: %w", err)
 	}
-	stages = stages[:targetStage+1]
+	stages = stages[:finalStage+1]
 
 	stageByName := make(map[string]int)
 	for idx, s := range stages {
@@ -282,11 +297,18 @@ func MakeKanikoStages(opts *config.KanikoOptions, stages []instructions.Stage, m
 	kanikoStages := make([]config.KanikoStage, len(stages))
 	// We now "count" references, it is only safe to squash
 	// stages if the references are exactly 1 and there are no COPY references
+	buildTargets := make([]bool, len(stages))
 	stagesDependencies := make([]int, len(stages))
 	copyDependencies := make([]int, len(stages))
-	stagesDependencies[targetStage] = 1
-	for i := targetStage; i >= 0; i-- {
-		if stagesDependencies[i] == 0 && copyDependencies[i] == 0 && opts.SkipUnusedStages {
+	for _, x := range targetStages {
+		// buildTargets we just need to visit, but they
+		// can be squashed together, we don't care.
+		buildTargets[x] = true
+	}
+	// push stage cannot be squashed
+	stagesDependencies[pushStage] = 1
+	for i := finalStage; i >= 0; i-- {
+		if !buildTargets[i] && stagesDependencies[i] == 0 && copyDependencies[i] == 0 && opts.SkipUnusedStages {
 			continue
 		}
 		stage := stages[i]
@@ -331,14 +353,15 @@ func MakeKanikoStages(opts *config.KanikoOptions, stages []instructions.Stage, m
 			BaseImageIndex:         baseImageIndex,
 			BaseImageStoredLocally: baseImageStoredLocally,
 			SaveStage:              stagesDependencies[i] > 0,
-			Final:                  i == targetStage,
+			Push:                   i == pushStage,
+			Final:                  i == finalStage,
 			MetaArgs:               metaArgs,
 			Index:                  i,
 		}
 	}
 	if opts.SkipUnusedStages && config.EnvBoolDefault("FF_KANIKO_SQUASH_STAGES", true) {
 		for i, s := range kanikoStages {
-			if stagesDependencies[i] > 0 || copyDependencies[i] > 0 {
+			if buildTargets[i] || stagesDependencies[i] > 0 || copyDependencies[i] > 0 {
 				if s.BaseImageStoredLocally && stagesDependencies[s.BaseImageIndex] == 1 && copyDependencies[s.BaseImageIndex] == 0 {
 					sb := kanikoStages[s.BaseImageIndex]
 					// squash stages[i] into stages[i].BaseName
@@ -355,7 +378,7 @@ func MakeKanikoStages(opts *config.KanikoOptions, stages []instructions.Stage, m
 	if opts.SkipUnusedStages {
 		var onlyUsedStages []config.KanikoStage
 		for i, s := range kanikoStages {
-			if stagesDependencies[i] > 0 || copyDependencies[i] > 0 {
+			if buildTargets[i] || stagesDependencies[i] > 0 || copyDependencies[i] > 0 {
 				s.SaveStage = stagesDependencies[i] > 0
 				onlyUsedStages = append(onlyUsedStages, s)
 			}
@@ -433,6 +456,7 @@ func squash(a, b config.KanikoStage) config.KanikoStage {
 		BaseName:               a.BaseName,
 		Commands:               append(acmds, b.Commands...),
 		BaseImageIndex:         a.BaseImageIndex,
+		Push:                   b.Push,
 		Final:                  b.Final,
 		BaseImageStoredLocally: a.BaseImageStoredLocally,
 		SaveStage:              b.SaveStage,

pkg/dockerfile/dockerfile_test.go

@@ -304,9 +304,17 @@ func Test_targetStage(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
-			target, err := targetStage(stages, test.target)
+			var targs []string
+			if test.target != "" {
+				targs = []string{test.target}
+			}
+			targets, err := targetStages(stages, targs)
 			testutil.CheckError(t, test.shouldErr, err)
 			if !test.shouldErr {
+				if len(targets) != 1 {
+					t.Errorf("Expected one target, received %d", len(targets))
+				}
+				target := targets[0]
 				if target != test.targetIndex {
 					t.Errorf("got incorrect target, expected %d got %d", test.targetIndex, target)
 				}

pkg/executor/build.go

@@ -93,7 +93,7 @@ func newStageBuilder(args *dockerfile.BuildArgs, opts *config.KanikoOptions, sta
 	}
 
 	_opts := *opts
-	if !stage.Final {
+	if !stage.Push {
 		_opts.Labels = []string{}
 	}
 	imageConfig, err := initializeConfig(sourceImage, &_opts)
@@ -741,10 +741,10 @@ func RenderStages(stages []config.KanikoStage, opts *config.KanikoOptions, fileC
 			}
 			printf("%s\n", command)
 		}
+		if s.Push && !opts.NoPush {
+			printf("PUSH %v\n", opts.Destinations)
+		}
 		if s.Final {
-			if !opts.NoPush {
-				printf("PUSH %v\n", opts.Destinations)
-			}
 			if opts.Cleanup {
 				printf("CLEAN\n")
 			}
@@ -762,7 +762,7 @@ func RenderStages(stages []config.KanikoStage, opts *config.KanikoOptions, fileC
 			printf("RESTORE CONTEXT\n\n")
 		}
 	}
-	logrus.Panic("unreachable - we should always have a final stage")
+	logrus.Panic("Unreachable Code: we should always have a final stage")
 	return retErr
 }
 
@@ -860,6 +860,7 @@ func DoBuild(opts *config.KanikoOptions) (image v1.Image, retErr error) {
 		})
 	}
 
+	var pushImage v1.Image
 	for _, stage := range kanikoStages {
 		sb, err := newStageBuilder(
 			args, opts, stage,
@@ -923,7 +924,7 @@ func DoBuild(opts *config.KanikoOptions) (image v1.Image, retErr error) {
 		digestToCacheKey[d.String()] = finalCacheKey
 		logrus.Debugf("Mapping digest %v to cachekey %v", d.String(), finalCacheKey)
 
-		if stage.Final {
+		if stage.Push {
 			sourceImage, err = mutate.CreatedAt(sourceImage, v1.Time{Time: time.Now()})
 			if err != nil {
 				return nil, err
@@ -937,8 +938,15 @@ func DoBuild(opts *config.KanikoOptions) (image v1.Image, retErr error) {
 			if len(opts.Annotations) > 0 {
 				sourceImage = mutate.Annotations(sourceImage, opts.Annotations).(v1.Image)
 			}
+			pushImage = sourceImage
+		}
+		if stage.Final {
 			timing.DefaultRun.Stop(t)
-			return sourceImage, nil
+			if pushImage == nil {
+				// Final stage must be last, so by definition after Push stage
+				logrus.Panic("pushImage is nil")
+			}
+			return pushImage, nil
 		}
 		if stage.SaveStage {
 			if err := saveStageAsTarball(strconv.Itoa(stage.Index), sourceImage); err != nil {