Add --disable-optimizations flag to make debugging easier.

.gitignore

@@ -0,0 +1,3 @@
+# Ignore GoLand (IntelliJ) files.
+.idea/
+

cmd/ko/commands.go

@@ -70,6 +70,7 @@ func addKubeCommands(topLevel *cobra.Command) {
 	no := &NameOptions{}
 	fo := &FilenameOptions{}
 	ta := &TagsOptions{}
+	do := &DebugOptions{}
 	apply := &cobra.Command{
 		Use:   "apply -f FILENAME",
 		Short: "Apply the input files with image references resolved to built/pushed image digests.",
@@ -144,7 +145,7 @@ func addKubeCommands(topLevel *cobra.Command) {
 					stdin.Write([]byte("---\n"))
 				}
 				// Once primed kick things off.
-				resolveFilesToWriter(fo, no, lo, ta, stdin)
+				resolveFilesToWriter(fo, no, lo, ta, do, stdin)
 			}()
 
 			// Run it.
@@ -157,6 +158,7 @@ func addKubeCommands(topLevel *cobra.Command) {
 	addNamingArgs(apply, no)
 	addFileArg(apply, fo)
 	addTagsArg(apply, ta)
+	addDebugArg(apply, do)
 
 	// Collect the ko-specific apply flags before registering the kubectl global
 	// flags so that we can ignore them when passing kubectl global flags through
@@ -197,13 +199,14 @@ func addKubeCommands(topLevel *cobra.Command) {
   ko resolve --local -f config/`,
 		Args: cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			resolveFilesToWriter(fo, no, lo, ta, os.Stdout)
+			resolveFilesToWriter(fo, no, lo, ta, do, os.Stdout)
 		},
 	}
 	addLocalArg(resolve, lo)
 	addNamingArgs(resolve, no)
 	addFileArg(resolve, fo)
 	addTagsArg(resolve, ta)
+	addDebugArg(resolve, do)
 	topLevel.AddCommand(resolve)
 
 	publish := &cobra.Command{
@@ -237,12 +240,13 @@ func addKubeCommands(topLevel *cobra.Command) {
   ko publish --local github.com/foo/bar/cmd/baz github.com/foo/bar/cmd/blah`,
 		Args: cobra.MinimumNArgs(1),
 		Run: func(_ *cobra.Command, args []string) {
-			publishImages(args, no, lo, ta)
+			publishImages(args, no, lo, ta, do)
 		},
 	}
 	addLocalArg(publish, lo)
 	addNamingArgs(publish, no)
 	addTagsArg(publish, ta)
+	addDebugArg(publish, do)
 	topLevel.AddCommand(publish)
 
 	run := &cobra.Command{
@@ -259,7 +263,7 @@ func addKubeCommands(topLevel *cobra.Command) {
   # This supports relative import paths as well.
   ko run foo --image=./cmd/baz`,
 		Run: func(cmd *cobra.Command, args []string) {
-			imgs := publishImages([]string{bo.Path}, no, lo, ta)
+			imgs := publishImages([]string{bo.Path}, no, lo, ta, do)
 
 			// There's only one, but this is the simple way to access the
 			// reference since the import path may have been qualified.
@@ -293,6 +297,7 @@ func addKubeCommands(topLevel *cobra.Command) {
 	addNamingArgs(run, no)
 	addImageArg(run, bo)
 	addTagsArg(run, ta)
+	addDebugArg(run, do)
 
 	topLevel.AddCommand(run)
 }

cmd/ko/debug.go

@@ -0,0 +1,29 @@
+// Copyright 2019 Google LLC All Rights Reserved.
+//
+// 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.
+
+package main
+
+import (
+	"github.com/spf13/cobra"
+)
+
+// DebugOptions holds options to improve debugging containers.
+type DebugOptions struct {
+	DisableOptimizations bool
+}
+
+func addDebugArg(cmd *cobra.Command, do *DebugOptions) {
+	cmd.Flags().BoolVar(&do.DisableOptimizations, "disable-optimizations", do.DisableOptimizations,
+		"Disable optimizations when building Go code. Useful when you want to interactively debug the created container.")
+}

cmd/ko/publish.go

@@ -38,8 +38,8 @@ func qualifyLocalImport(importpath, gopathsrc, pwd string) (string, error) {
 	return filepath.Join(strings.TrimPrefix(pwd, gopathsrc+string(filepath.Separator)), importpath), nil
 }
 
-func publishImages(importpaths []string, no *NameOptions, lo *LocalOptions, ta *TagsOptions) map[string]name.Reference {
-	opt, err := gobuildOptions()
+func publishImages(importpaths []string, no *NameOptions, lo *LocalOptions, ta *TagsOptions, do *DebugOptions) map[string]name.Reference {
+	opt, err := gobuildOptions(do)
 	if err != nil {
 		log.Fatalf("error setting up builder options: %v", err)
 	}

cmd/ko/resolve.go

@@ -30,7 +30,7 @@ import (
 	"github.com/mattmoor/dep-notify/pkg/graph"
 )
 
-func gobuildOptions() ([]build.Option, error) {
+func gobuildOptions(do *DebugOptions) ([]build.Option, error) {
 	creationTime, err := getCreationTime()
 	if err != nil {
 		return nil, err
@@ -41,11 +41,14 @@ func gobuildOptions() ([]build.Option, error) {
 	if creationTime != nil {
 		opts = append(opts, build.WithCreationTime(*creationTime))
 	}
+	if do.DisableOptimizations {
+		opts = append(opts, build.WithDisabledOptimizations())
+	}
 	return opts, nil
 }
 
-func makeBuilder() (*build.Caching, error) {
-	opt, err := gobuildOptions()
+func makeBuilder(do *DebugOptions) (*build.Caching, error) {
+	opt, err := gobuildOptions(do)
 	if err != nil {
 		log.Fatalf("error setting up builder options: %v", err)
 	}
@@ -104,9 +107,9 @@ func makePublisher(no *NameOptions, lo *LocalOptions, ta *TagsOptions) (publish.
 // resolvedFuture represents a "future" for the bytes of a resolved file.
 type resolvedFuture chan []byte
 
-func resolveFilesToWriter(fo *FilenameOptions, no *NameOptions, lo *LocalOptions, ta *TagsOptions, out io.WriteCloser) {
+func resolveFilesToWriter(fo *FilenameOptions, no *NameOptions, lo *LocalOptions, ta *TagsOptions, do *DebugOptions, out io.WriteCloser) {
 	defer out.Close()
-	builder, err := makeBuilder()
+	builder, err := makeBuilder(do)
 	if err != nil {
 		log.Fatalf("error creating builder: %v", err)
 	}

pkg/build/gobuild.go

@@ -38,12 +38,13 @@ const (
 
 // GetBase takes an importpath and returns a base v1.Image.
 type GetBase func(string) (v1.Image, error)
-type builder func(string) (string, error)
+type builder func(string, bool) (string, error)
 
 type gobuild struct {
 	getBase      GetBase
 	creationTime v1.Time
 	build        builder
+	disableOptimizations bool
 }
 
 // Option is a functional option for NewGo.
@@ -53,6 +54,7 @@ type gobuildOpener struct {
 	getBase      GetBase
 	creationTime v1.Time
 	build        builder
+	disableOptimizations bool
 }
 
 func (gbo *gobuildOpener) Open() (Interface, error) {
@@ -63,6 +65,7 @@ func (gbo *gobuildOpener) Open() (Interface, error) {
 		getBase:      gbo.getBase,
 		creationTime: gbo.creationTime,
 		build:        gbo.build,
+		disableOptimizations: gbo.disableOptimizations,
 	}, nil
 }
 
@@ -94,14 +97,22 @@ func (*gobuild) IsSupportedReference(s string) bool {
 	return p.IsCommand()
 }
 
-func build(ip string) (string, error) {
+func build(ip string, disableOptimizations bool) (string, error) {
 	tmpDir, err := ioutil.TempDir("", "ko")
 	if err != nil {
 		return "", err
 	}
 	file := filepath.Join(tmpDir, "out")
 
-	cmd := exec.Command("go", "build", "-o", file, ip)
+	args := make([]string, 0, 6)
+	args = append(args, "build")
+	if disableOptimizations {
+		// Disable optimizations (-N) and inlining (-l).
+		args = append(args, "-gcflags", "all=-N -l")
+	}
+	args = append(args, "-o", file)
+	args = append(args, ip)
+	cmd := exec.Command("go", args...)
 
 	// Last one wins
 	// TODO(mattmoor): GOARCH=amd64
@@ -273,7 +284,7 @@ func tarKoData(importpath string) (*bytes.Buffer, error) {
 // Build implements build.Interface
 func (gb *gobuild) Build(s string) (v1.Image, error) {
 	// Do the build into a temporary file.
-	file, err := gb.build(s)
+	file, err := gb.build(s, gb.disableOptimizations)
 	if err != nil {
 		return nil, err
 	}

pkg/build/gobuild_test.go

@@ -62,7 +62,7 @@ func TestGoBuildIsSupportedRef(t *testing.T) {
 }
 
 // A helper method we use to substitute for the default "build" method.
-func writeTempFile(s string) (string, error) {
+func writeTempFile(s string, _ bool) (string, error) {
 	tmpDir, err := ioutil.TempDir("", "ko")
 	if err != nil {
 		return "", err

pkg/build/options.go

@@ -36,6 +36,15 @@ func WithCreationTime(t v1.Time) Option {
 	}
 }
 
+// WithDisabledOptimizations is a functional option for disabling optimizations
+// when compiling.
+func WithDisabledOptimizations() Option {
+	return func(gbo *gobuildOpener) error {
+		gbo.disableOptimizations = true
+		return nil
+	}
+}
+
 // withBuilder is a functional option for overriding the way go binaries
 // are built.  This is exposed for testing.
 func withBuilder(b builder) Option {