fix: unable to build multigroup projects

pkg/scaffold/edit.go

@@ -17,6 +17,10 @@ limitations under the License.
 package scaffold
 
 import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+
 	"sigs.k8s.io/kubebuilder/pkg/model/config"
 )
 
@@ -38,5 +42,38 @@ func NewEditScaffolder(config *config.Config, multigroup bool) Scaffolder {
 // Scaffold implements Scaffolder
 func (s *editScaffolder) Scaffold() error {
 	s.config.MultiGroup = s.multigroup
-	return nil
+	filename := "Dockerfile"
+	bs, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return err
+	}
+	str := string(bs)
+
+	// update dockerfile
+	if s.multigroup {
+		str, err = ensureExistAndReplace(
+			str,
+			"COPY api/ api/",
+			`COPY apis/ apis/`)
+		if err != nil {
+			return err
+		}
+	} else {
+		str, err = ensureExistAndReplace(
+			str,
+			"COPY apis/ apis/",
+			`COPY api/ api/`)
+		if err != nil {
+			return err
+		}
+	}
+
+	return ioutil.WriteFile(filename, []byte(str), 0644)
+}
+
+func ensureExistAndReplace(input, match, replace string) (string, error) {
+	if !strings.Contains(input, match) {
+		return "", fmt.Errorf("can't find %q", match)
+	}
+	return strings.Replace(input, match, replace, -1), nil
 }

testdata/project-v2-multigroup/Dockerfile

@@ -11,7 +11,7 @@ RUN go mod download
 
 # Copy the go source
 COPY main.go main.go
-COPY api/ api/
+COPY apis/ apis/
 COPY controllers/ controllers/
 
 # Build

testdata/project-v3-multigroup/Dockerfile

@@ -11,7 +11,7 @@ RUN go mod download
 
 # Copy the go source
 COPY main.go main.go
-COPY api/ api/
+COPY apis/ apis/
 COPY controllers/ controllers/
 
 # Build