Exit Code Propagation (#1655)

* exit codes of failed RUN commands may now be propagated to the caller by using the --propagate-exit-code flag

* removed exit code propagation flag; the exit function now unwraps the error and looks for an exit code

* added integration test for exit code propagation

* added trailing new line in test Dockerfile_exit_code_propagation; tidying up README.md removing all traces of error propagation flag

* moved exit code propagation test to integration_test.go; moved exit code propagation test files to 'testdata' to avoid interference with other integration tests

cmd/executor/cmd/root.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -340,8 +341,19 @@ func resolveRelativePaths() error {
 }
 
 func exit(err error) {
+	var execErr *exec.ExitError
+	if errors.As(err, &execErr) {
+		// if there is an exit code propagate it
+		exitWithCode(err, execErr.ExitCode())
+	}
+	// otherwise exit with catch all 1
+	exitWithCode(err, 1)
+}
+
+//exits with the given error and exit code
+func exitWithCode(err error, exitCode int) {
 	fmt.Println(err)
-	os.Exit(1)
+	os.Exit(exitCode)
 }
 
 func isURL(path string) bool {

integration/integration_test.go

@@ -528,6 +528,63 @@ func TestRelativePaths(t *testing.T) {
 	})
 }
 
+func TestExitCodePropagation(t *testing.T) {
+
+	currentDir, err := os.Getwd()
+	if err != nil {
+		t.Fatal("Could not get working dir")
+	}
+
+	context := fmt.Sprintf("%s/testdata/exit-code-propagation", currentDir)
+	dockerfile := fmt.Sprintf("%s/Dockerfile_exit_code_propagation", context)
+
+	t.Run("test error code propagation", func(t *testing.T) {
+		// building the image with docker should fail with exit code 42
+		dockerImage := GetDockerImage(config.imageRepo, "Dockerfile_exit_code_propagation")
+		dockerCmd := exec.Command("docker",
+			append([]string{"build",
+				"-t", dockerImage,
+				"-f", dockerfile,
+				context})...)
+		_, kanikoErr := RunCommandWithoutTest(dockerCmd)
+		if kanikoErr == nil {
+			t.Fatal("docker build did not produce an error")
+		}
+		var dockerCmdExitErr *exec.ExitError
+		var dockerExitCode int
+
+		if errors.As(kanikoErr, &dockerCmdExitErr) {
+			dockerExitCode = dockerCmdExitErr.ExitCode()
+			testutil.CheckDeepEqual(t, 42, dockerExitCode)
+		} else {
+			t.Fatalf("did not produce the expected error")
+		}
+
+		//try to build the same image with kaniko the error code should match with the one from the plain docker build
+		contextVolume := fmt.Sprintf("%s:/workspace", context)
+		dockerCmdWithKaniko := exec.Command("docker", append([]string{
+			"run",
+			"-v", contextVolume,
+			ExecutorImage,
+			"-c", "dir:///workspace/",
+			"-f", "./Dockerfile_exit_code_propagation",
+			"--no-push",
+		})...)
+
+		_, kanikoErr = RunCommandWithoutTest(dockerCmdWithKaniko)
+		if kanikoErr == nil {
+			t.Fatal("the kaniko build did not produce the expected error")
+		}
+
+		var kanikoExitErr *exec.ExitError
+		if errors.As(kanikoErr, &kanikoExitErr) {
+			testutil.CheckDeepEqual(t, dockerExitCode, kanikoExitErr.ExitCode())
+		} else {
+			t.Fatalf("did not produce the expected error")
+		}
+	})
+}
+
 type fileDiff struct {
 	Name string
 	Size int

integration/testdata/exit-code-propagation/Dockerfile_exit_code_propagation

@@ -0,0 +1,5 @@
+FROM alpine:latest
+
+RUN exit 42
+
+CMD ["sleep", "1"]