Review config for cmd/entrypoint after building a stage

integration/dockerfiles/Dockerfile_test_cmd

@@ -0,0 +1,5 @@
+FROM gcr.io/distroless/base@sha256:628939ac8bf3f49571d05c6c76b8688cb4a851af6c7088e599388259875bde20 AS first
+CMD ["mycmd"]
+
+FROM first
+ENTRYPOINT ["myentrypoint"] # This should clear out CMD in the config metadata

pkg/commands/cmd.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/google/go-containerregistry/pkg/v1"
 	"github.com/moby/buildkit/frontend/dockerfile/instructions"
-	"github.com/sirupsen/logrus"
 )
 
 type CmdCommand struct {
@@ -48,7 +47,6 @@ func (c *CmdCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bui
 		newCommand = c.cmd.CmdLine
 	}
 
-	logrus.Infof("Replacing CMD in config with %v", newCommand)
 	config.Cmd = newCommand
 	config.ArgsEscaped = true
 	return nil

pkg/commands/entrypoint.go

@@ -23,7 +23,6 @@ import (
 
 	"github.com/google/go-containerregistry/pkg/v1"
 	"github.com/moby/buildkit/frontend/dockerfile/instructions"
-	"github.com/sirupsen/logrus"
 )
 
 type EntrypointCommand struct {
@@ -47,7 +46,6 @@ func (e *EntrypointCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerf
 		newCommand = e.cmd.CmdLine
 	}
 
-	logrus.Infof("Replacing Entrypoint in config with %v", newCommand)
 	config.Entrypoint = newCommand
 	return nil
 }

pkg/constants/constants.go

@@ -55,9 +55,13 @@ const (
 	S3BuildContextPrefix       = "s3://"
 	LocalDirBuildContextPrefix = "dir://"
 
+	HOME = "HOME"
 	// DefaultHOMEValue is the default value Docker sets for $HOME
-	HOME             = "HOME"
 	DefaultHOMEValue = "/root"
+
+	// Docker command names
+	Cmd        = "cmd"
+	Entrypoint = "entrypoint"
 )
 
 // KanikoBuildFiles is the list of files required to build kaniko

pkg/executor/build.go

@@ -194,6 +194,7 @@ func DoBuild(opts *config.KanikoOptions) (v1.Image, error) {
 		if err := sb.build(opts); err != nil {
 			return nil, errors.Wrap(err, "error building stage")
 		}
+		reviewConfig(stage, &sb.cf.Config)
 		sourceImage, err := mutate.Config(sb.image, sb.cf.Config)
 		if err != nil {
 			return nil, err
@@ -277,3 +278,23 @@ func resolveOnBuild(stage *config.KanikoStage, config *v1.Config) error {
 	config.OnBuild = nil
 	return nil
 }
+
+// reviewConfig makes sure the value of CMD is correct after building the stage
+// If ENTRYPOINT was set in this stage but CMD wasn't, then CMD should be cleared out
+// See Issue #346 for more info
+func reviewConfig(stage config.KanikoStage, config *v1.Config) {
+	entrypoint := false
+	cmd := false
+
+	for _, c := range stage.Commands {
+		if c.Name() == constants.Cmd {
+			cmd = true
+		}
+		if c.Name() == constants.Entrypoint {
+			entrypoint = true
+		}
+	}
+	if entrypoint && !cmd {
+		config.Cmd = nil
+	}
+}

pkg/executor/build_test.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2018 Google LLC
+
+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 executor
+
+import (
+	"testing"
+
+	"github.com/GoogleContainerTools/kaniko/pkg/config"
+	"github.com/GoogleContainerTools/kaniko/pkg/dockerfile"
+	"github.com/GoogleContainerTools/kaniko/testutil"
+	"github.com/google/go-containerregistry/pkg/v1"
+)
+
+func Test_reviewConfig(t *testing.T) {
+	tests := []struct {
+		name               string
+		dockerfile         string
+		originalCmd        []string
+		originalEntrypoint []string
+		expectedCmd        []string
+	}{
+		{
+			name: "entrypoint and cmd declared",
+			dockerfile: `
+			FROM scratch
+			CMD ["mycmd"]
+			ENTRYPOINT ["myentrypoint"]`,
+			originalEntrypoint: []string{"myentrypoint"},
+			originalCmd:        []string{"mycmd"},
+			expectedCmd:        []string{"mycmd"},
+		},
+		{
+			name: "only entrypoint declared",
+			dockerfile: `
+			FROM scratch
+			ENTRYPOINT ["myentrypoint"]`,
+			originalEntrypoint: []string{"myentrypoint"},
+			originalCmd:        []string{"mycmd"},
+			expectedCmd:        nil,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			config := &v1.Config{
+				Cmd:        test.originalCmd,
+				Entrypoint: test.originalEntrypoint,
+			}
+			reviewConfig(stage(t, test.dockerfile), config)
+			testutil.CheckErrorAndDeepEqual(t, false, nil, test.expectedCmd, config.Cmd)
+		})
+	}
+}
+
+func stage(t *testing.T, d string) config.KanikoStage {
+	stages, err := dockerfile.Parse([]byte(d))
+	if err != nil {
+		t.Fatalf("error parsing dockerfile: %v", err)
+	}
+	return config.KanikoStage{
+		Stage: stages[0],
+	}
+}