Add support for starting debugged application without waiting for a debugger to attach

docs/features/debugging.md

@@ -27,3 +27,9 @@ docker run -p 40000:40000 <img>
 ```
 
 This sets up your app to be waiting to run the command you've specified. All that's needed now is to connect your debugger client to the running container!
+
+By default, the application will not start until a debugger has connected and issued the `continue` command. This is required in order to be able to set breakpoints for code that is executed during start-up. If you want the application to start running without waiting for a debugger, use the `--debug-continue` parameter:
+
+```plaintext
+ko build . --debug --debug-continue
+```

docs/reference/ko_apply.md

@@ -48,6 +48,7 @@ ko apply -f FILENAME [flags]
       --bare                       Whether to just use KO_DOCKER_REPO without additional context (may not work properly with --tags).
   -B, --base-import-paths          Whether to use the base path without MD5 hash after KO_DOCKER_REPO (may not work properly with --tags).
       --debug                      Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.
+      --debug-continue             Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.
       --disable-optimizations      Disable optimizations when building Go code. Useful when you want to interactively debug the created container.
   -f, --filename strings           Filename, directory, or URL to files to use to create the resource
   -h, --help                       help for apply

docs/reference/ko_build.md

@@ -45,6 +45,7 @@ ko build IMPORTPATH... [flags]
       --bare                       Whether to just use KO_DOCKER_REPO without additional context (may not work properly with --tags).
   -B, --base-import-paths          Whether to use the base path without MD5 hash after KO_DOCKER_REPO (may not work properly with --tags).
       --debug                      Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.
+      --debug-continue             Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.
       --disable-optimizations      Disable optimizations when building Go code. Useful when you want to interactively debug the created container.
   -h, --help                       help for build
       --image-annotation strings   Which annotations (key=value[,key=value]) to add to the OCI manifest.

docs/reference/ko_create.md

@@ -48,6 +48,7 @@ ko create -f FILENAME [flags]
       --bare                       Whether to just use KO_DOCKER_REPO without additional context (may not work properly with --tags).
   -B, --base-import-paths          Whether to use the base path without MD5 hash after KO_DOCKER_REPO (may not work properly with --tags).
       --debug                      Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.
+      --debug-continue             Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.
       --disable-optimizations      Disable optimizations when building Go code. Useful when you want to interactively debug the created container.
   -f, --filename strings           Filename, directory, or URL to files to use to create the resource
   -h, --help                       help for create

docs/reference/ko_resolve.md

@@ -41,6 +41,7 @@ ko resolve -f FILENAME [flags]
       --bare                       Whether to just use KO_DOCKER_REPO without additional context (may not work properly with --tags).
   -B, --base-import-paths          Whether to use the base path without MD5 hash after KO_DOCKER_REPO (may not work properly with --tags).
       --debug                      Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.
+      --debug-continue             Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.
       --disable-optimizations      Disable optimizations when building Go code. Useful when you want to interactively debug the created container.
   -f, --filename strings           Filename, directory, or URL to files to use to create the resource
   -h, --help                       help for resolve

docs/reference/ko_run.md

@@ -33,6 +33,7 @@ ko run IMPORTPATH [flags]
       --bare                       Whether to just use KO_DOCKER_REPO without additional context (may not work properly with --tags).
   -B, --base-import-paths          Whether to use the base path without MD5 hash after KO_DOCKER_REPO (may not work properly with --tags).
       --debug                      Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.
+      --debug-continue             Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.
       --disable-optimizations      Disable optimizations when building Go code. Useful when you want to interactively debug the created container.
   -h, --help                       help for run
       --image-annotation strings   Which annotations (key=value[,key=value]) to add to the OCI manifest.

pkg/build/gobuild.go

@@ -105,6 +105,7 @@ type gobuild struct {
 	annotations          map[string]string
 	user                 string
 	debug                bool
+	debugContinue        bool
 	semaphore            *semaphore.Weighted
 
 	cache *layerCache
@@ -134,6 +135,7 @@ type gobuildOpener struct {
 	dir                  string
 	jobs                 int
 	debug                bool
+	debugContinue        bool
 }
 
 func (gbo *gobuildOpener) Open() (Interface, error) {
@@ -169,6 +171,7 @@ func (gbo *gobuildOpener) Open() (Interface, error) {
 		annotations:          gbo.annotations,
 		dir:                  gbo.dir,
 		debug:                gbo.debug,
+		debugContinue:        gbo.debugContinue,
 		platformMatcher:      matcher,
 		cache: &layerCache{
 			buildToDiff: map[string]buildIDToDiffID{},
@@ -1129,6 +1132,7 @@ func (g *gobuild) buildOne(ctx context.Context, refStr string, base v1.Image, pl
 		"--log",
 		"--accept-multiclient",
 		"--api-version=2",
+		fmt.Sprintf("--continue=%t", g.debugContinue),
 		"--",
 	}
 

pkg/build/gobuild_test.go

@@ -1498,52 +1498,88 @@ func TestDebugger(t *testing.T) {
 	}
 	importpath := "github.com/google/ko"
 
-	ng, err := NewGo(
-		context.Background(),
-		"",
-		WithBaseImages(func(context.Context, string) (name.Reference, Result, error) { return baseRef, base, nil }),
-		WithPlatforms("linux/amd64"),
-		WithDebugger(),
-	)
-	if err != nil {
-		t.Fatalf("NewGo() = %v", err)
+	tests := []struct {
+		desc           string
+		opts           []Option
+		wantEntrypoint []string
+	}{
+		{
+			desc: "debugger enabled",
+			opts: []Option{
+				WithBaseImages(func(context.Context, string) (name.Reference, Result, error) { return baseRef, base, nil }),
+				WithPlatforms("linux/amd64"),
+				WithDebugger(),
+			},
+			wantEntrypoint: []string{
+				"/ko-app/dlv",
+				"exec",
+				"--listen=:40000",
+				"--headless",
+				"--log",
+				"--accept-multiclient",
+				"--api-version=2",
+				"--continue=false",
+				"--",
+				"/ko-app/ko",
+			},
+		},
+		{
+			desc: "debugger enabled with continue",
+			opts: []Option{
+				WithBaseImages(func(context.Context, string) (name.Reference, Result, error) { return baseRef, base, nil }),
+				WithPlatforms("linux/amd64"),
+				WithDebugger(),
+				WithDebuggerContinue(),
+			},
+			wantEntrypoint: []string{
+				"/ko-app/dlv",
+				"exec",
+				"--listen=:40000",
+				"--headless",
+				"--log",
+				"--accept-multiclient",
+				"--api-version=2",
+				"--continue=true",
+				"--",
+				"/ko-app/ko",
+			},
+		},
 	}
 
-	result, err := ng.Build(context.Background(), StrictScheme+importpath)
-	if err != nil {
-		t.Fatalf("Build() = %v", err)
-	}
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			ng, err := NewGo(context.Background(), "", tc.opts...)
+			if err != nil {
+				t.Fatalf("NewGo() = %v", err)
+			}
 
-	img, ok := result.(v1.Image)
-	if !ok {
-		t.Fatalf("Build() not an Image: %T", result)
-	}
+			result, err := ng.Build(context.Background(), StrictScheme+importpath)
+			if err != nil {
+				t.Fatalf("Build() = %v", err)
+			}
 
-	// Check that the entrypoint of the image is not overwritten
-	cfg, err := img.ConfigFile()
-	if err != nil {
-		t.Errorf("ConfigFile() = %v", err)
-	}
-	gotEntrypoint := cfg.Config.Entrypoint
-	wantEntrypoint := []string{
-		"/ko-app/dlv",
-		"exec",
-		"--listen=:40000",
-		"--headless",
-		"--log",
-		"--accept-multiclient",
-		"--api-version=2",
-		"--",
-		"/ko-app/ko",
-	}
+			img, ok := result.(v1.Image)
+			if !ok {
+				t.Fatalf("Build() not an Image: %T", result)
+			}
 
-	if got, want := len(gotEntrypoint), len(wantEntrypoint); got != want {
-		t.Fatalf("len(entrypoint) = %v, want %v", got, want)
-	}
+			// Check that the entrypoint of the image is not overwritten
+			cfg, err := img.ConfigFile()
+			if err != nil {
+				t.Errorf("ConfigFile() = %v", err)
+			}
+			gotEntrypoint := cfg.Config.Entrypoint
+			wantEntrypoint := tc.wantEntrypoint
 
-	for i := range wantEntrypoint {
-		if got, want := gotEntrypoint[i], wantEntrypoint[i]; got != want {
-			t.Errorf("entrypoint[%d] = %v, want %v", i, got, want)
-		}
+			if got, want := len(gotEntrypoint), len(wantEntrypoint); got != want {
+				t.Fatalf("len(entrypoint) = %v, want %v", got, want)
+			}
+
+			for i := range wantEntrypoint {
+				if got, want := gotEntrypoint[i], wantEntrypoint[i]; got != want {
+					t.Errorf("entrypoint[%d] = %v, want %v", i, got, want)
+				}
+			}
+		})
 	}
 }

pkg/build/options.go

@@ -210,3 +210,10 @@ func WithDebugger() Option {
 		return nil
 	}
 }
+
+func WithDebuggerContinue() Option {
+	return func(gbo *gobuildOpener) error {
+		gbo.debugContinue = true
+		return nil
+	}
+}

pkg/commands/options/build.go

@@ -68,6 +68,7 @@ type BuildOptions struct {
 	Annotations          []string
 	User                 string
 	Debug                bool
+	DebugContinue        bool
 	// UserAgent enables overriding the default value of the `User-Agent` HTTP
 	// request header used when retrieving the base image.
 	UserAgent string
@@ -103,6 +104,8 @@ func AddBuildOptions(cmd *cobra.Command, bo *BuildOptions) {
 		"The default user the image should be run as.")
 	cmd.Flags().BoolVar(&bo.Debug, "debug", bo.Debug,
 		"Include Delve debugger into image and wrap around ko-app. This debugger will listen to port 40000.")
+	cmd.Flags().BoolVar(&bo.DebugContinue, "debug-continue", bo.DebugContinue,
+		"Continue the debugged process on start. Useful when you don't want to require a debugger to attach for the application to start.")
 	bo.Trimpath = true
 }
 

pkg/commands/resolver.go

@@ -104,6 +104,10 @@ func gobuildOptions(bo *options.BuildOptions) ([]build.Option, error) {
 	if bo.Debug {
 		opts = append(opts, build.WithDebugger())
 		opts = append(opts, build.WithDisabledOptimizations()) // also needed for Delve
+
+		if bo.DebugContinue {
+			opts = append(opts, build.WithDebuggerContinue())
+		}
 	}
 	switch bo.SBOM {
 	case "none":