Switch from containers/image to go-containerregistry (#140)

* Vendor changes for go-containerregistry switch.

* Manual changes for go-containerregistry switch.

The biggest change is refactoring the tarball unpacking.

* Pull more of container-diff out.

* More vendor removals.

* More unit tests.

pkg/image/image.go

@@ -17,80 +17,27 @@ limitations under the License.
 package image
 
 import (
-	"fmt"
 	"os"
+	"strings"
 
-	"github.com/GoogleContainerTools/kaniko/pkg/version"
-	"github.com/containers/image/types"
+	"github.com/google/go-containerregistry/v1"
 
-	img "github.com/GoogleContainerTools/container-diff/pkg/image"
-	"github.com/GoogleContainerTools/kaniko/pkg/constants"
-	"github.com/containers/image/copy"
-	"github.com/containers/image/docker"
-	"github.com/containers/image/signature"
-	"github.com/containers/image/transports/alltransports"
 	"github.com/sirupsen/logrus"
 )
 
-// sourceImage is the image that will be modified by the executor
-
-// NewSourceImage initializes the source image with the base image
-func NewSourceImage(srcImg string) (*img.MutableSource, error) {
-	if srcImg == constants.NoBaseImage {
-		return img.NewMutableSource(nil)
-	}
-	logrus.Infof("Initializing source image %s", srcImg)
-	ref, err := docker.ParseReference("//" + srcImg)
-	if err != nil {
-		return nil, err
-	}
-	return img.NewMutableSource(ref)
-}
-
-// PushImage pushes the final image
-func PushImage(ms *img.MutableSource, destImg string, dockerInsecureSkipTLSVerify bool) error {
-	srcRef := &img.ProxyReference{
-		ImageReference: nil,
-		Src:            ms,
-	}
-	destRef, err := alltransports.ParseImageName("docker://" + destImg)
-	if err != nil {
-		return err
-	}
-	policyContext, err := getPolicyContext()
-	if err != nil {
-		return err
-	}
-	logrus.Infof("Pushing image to %s", destImg)
-
-	opts := &copy.Options{
-		DestinationCtx: &types.SystemContext{
-			DockerRegistryUserAgent:     fmt.Sprintf("kaniko/executor-%s", version.Version()),
-			DockerInsecureSkipTLSVerify: dockerInsecureSkipTLSVerify,
-		},
-	}
-	return copy.Image(policyContext, destRef, srcRef, opts)
-}
-
 // SetEnvVariables sets environment variables as specified in the image
-func SetEnvVariables(ms *img.MutableSource) error {
-	envVars := ms.Env()
-	for key, val := range envVars {
-		if err := os.Setenv(key, val); err != nil {
+func SetEnvVariables(img v1.Image) error {
+	cfg, err := img.ConfigFile()
+	if err != nil {
+		return err
+	}
+	envVars := cfg.Config.Env
+	for _, envVar := range envVars {
+		split := strings.SplitN(envVar, "=", 2)
+		if err := os.Setenv(split[0], split[1]); err != nil {
 			return err
 		}
-		logrus.Debugf("Setting environment variable %s=%s", key, val)
+		logrus.Infof("Setting environment variable %s", envVar)
 	}
 	return nil
 }
-
-func getPolicyContext() (*signature.PolicyContext, error) {
-	policyContext, err := signature.NewPolicyContext(&signature.Policy{
-		Default: signature.PolicyRequirements{signature.NewPRInsecureAcceptAnything()},
-	})
-	if err != nil {
-		logrus.Debugf("Error retrieving policy context: %s", err)
-		return nil, err
-	}
-	return policyContext, nil
-}