add tests

cmd/skaffold/app/cmd/init.go

@@ -43,9 +43,10 @@ func NewCmdInit(out io.Writer) *cobra.Command {
 				CliArtifacts: cliArtifacts,
 				SkipBuild:    skipBuild,
 				Force:        force,
+				Analyze: analyze
 				SkaffoldOpts: opts,
 			}
-			return initializer.doInit(out, c)
+			return initializer.DoInit(out, c)
 		},
 	}
 	cmd.Flags().StringVarP(&opts.ConfigurationFile, "filename", "f", "skaffold.yaml", "Filename or URL to the pipeline file")

pkg/skaffold/initializer/init.go

@@ -18,6 +18,7 @@ package initializer
 
 import (
 	"bufio"
+	"encoding/json"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -49,6 +50,8 @@ const NoDockerfile = "None (image not built from these sources)"
 type Initializer interface {
 	// GenerateDeployConfig generates Deploy Config for skaffold configuration.
 	GenerateDeployConfig() latest.DeployConfig
+	// GetImages fetches all the images defined in the manifest files.
+	GetImages() []string
 }
 
 // Config defines the Initializer Config for Init API of skaffold.
@@ -58,9 +61,11 @@ type Config struct {
 	SkipBuild    bool
 	Force        bool
 	Opts         config.SkaffoldOptions
+	Analyze      bool
 }
 
-func doInit(out io.Writer, c Config) error {
+// DoInit executes the `skaffold init` flow.
+func DoInit(out io.Writer, c Config) error {
 	rootDir := "."
 
 	if c.ComposeFile != "" {
@@ -81,12 +86,15 @@ func doInit(out io.Writer, c Config) error {
 		if strings.HasPrefix(path, ".") {
 			return nil
 		}
-
-		if IsSupportedKubernetesFormat(path) {
+		if IsSkaffoldConfig(path) {
+			if !c.Force {
+				return fmt.Errorf("pre-existing %s found", path)
+			}
+			logrus.Debugf("%s is a valid skaffold configuration: continuing since --force=true", path)
+		} else if IsSupportedKubernetesFormat(path) {
 			potentialConfigs = append(potentialConfigs, path)
-		}
-		// try and parse dockerfile
-		if docker.ValidateDockerfile(path) {
+		} else if docker.ValidateDockerfile(path) {
+			// try and parse dockerfile
 			logrus.Infof("existing dockerfile found: %s", path)
 			dockerfiles = append(dockerfiles, path)
 		}
@@ -97,11 +105,14 @@ func doInit(out io.Writer, c Config) error {
 		return err
 	}
 
-	k, err := kubectl.New(potentialConfigs, c.Force)
+	k, err := kubectl.New(potentialConfigs)
 	if err != nil {
 		return err
 	}
-
+	images := k.GetImages()
+	if c.Analyze {
+		return printAnalyzeJSON(out, dockerfiles, images)
+	}
 	var pairs []dockerfilePair
 	// conditionally generate build artifacts
 	if !c.SkipBuild {
@@ -115,7 +126,7 @@ func doInit(out io.Writer, c Config) error {
 				return errors.Wrap(err, "processing cli artifacts")
 			}
 		} else {
-			pairs = resolveDockerfileImages(dockerfiles, k.Images())
+			pairs = resolveDockerfileImages(dockerfiles, images)
 		}
 	}
 
@@ -273,6 +284,22 @@ func generateSkaffoldPipeline(k Initializer, dockerfilePairs []dockerfilePair) (
 	return pipelineStr, nil
 }
 
+func printAnalyzeJSON(out io.Writer, dockerfiles, images []string) error {
+	a := struct {
+		Dockerfiles []string `json:"dockerfiles,omitempty"`
+		Images      []string `json:"images,omitempty"`
+	}{
+		Dockerfiles: dockerfiles,
+		Images:      images,
+	}
+	contents, err := json.Marshal(a)
+	if err != nil {
+		return errors.Wrap(err, "marshalling contents")
+	}
+	_, err = out.Write(contents)
+	return err
+}
+
 type dockerfilePair struct {
 	Dockerfile string
 	ImageName  string

pkg/skaffold/initializer/kubectl/kubectl.go

@@ -18,11 +18,9 @@ package kubectl
 
 import (
 	"bufio"
-	"fmt"
 	"io"
 	"os"
 
-	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -37,22 +35,15 @@ var ValidSuffixes = []string{".yml", ".yaml", ".json"}
 
 // Kubectl holds parameters to run kubectl.
 type Kubectl struct {
-	Configs []string
-	Images  []string
+	configs []string
+	images  []string
 }
 
 //New returns a Kubectl skaffold generator.
-func New(potentialConfigs []string, force bool) (*Kubectl, error) {
+func New(potentialConfigs []string) (*Kubectl, error) {
 	var k8sConfigs, images []string
 	for _, file := range potentialConfigs {
-		if !force {
-			config, err := schema.ParseConfig(file, false)
-			if err == nil && config != nil {
-				return nil, fmt.Errorf("pre-existing %s found", file)
-			}
-		}
-		logrus.Debugf("%s is not a valid skaffold configuration: continuing", file)
-		imgs, err := parseKubernetesYaml(file)
+		imgs, err := parseImagesFromKubernetesYaml(file)
 		if err == nil {
 			logrus.Infof("found valid k8s yaml: %s", file)
 			k8sConfigs = append(k8sConfigs, file)
@@ -65,8 +56,8 @@ func New(potentialConfigs []string, force bool) (*Kubectl, error) {
 		return nil, errors.New("one or more valid kubernetes manifests is required to run skaffold")
 	}
 	return &Kubectl{
-		Configs: k8sConfigs,
-		Images:  images,
+		configs: k8sConfigs,
+		images:  images,
 	}, nil
 }
 
@@ -76,16 +67,22 @@ func (k *Kubectl) GenerateDeployConfig() latest.DeployConfig {
 	return latest.DeployConfig{
 		DeployType: latest.DeployType{
 			KubectlDeploy: &latest.KubectlDeploy{
-				Manifests: k.Configs,
+				Manifests: k.configs,
 			},
 		},
 	}
 }
 
-// parseKubernetesYaml attempts to parse k8s objects from a yaml file
+// GetImages implements the Initializer interface and lists all the
+// images present in the k8 manifest files.
+func (k *Kubectl) GetImages() []string {
+	return k.images
+}
+
+// parseImagesFromKubernetesYaml attempts to parse k8s objects from a yaml file
 // if successful, it will return the images referenced in the k8s config
 // so they can be built by the generated skaffold yaml
-func parseKubernetesYaml(filepath string) ([]string, error) {
+func parseImagesFromKubernetesYaml(filepath string) ([]string, error) {
 	f, err := os.Open(filepath)
 	if err != nil {
 		return nil, errors.Wrap(err, "opening config file")