Hook up output directory cli option

Author: clareliguori

.gitignore

@@ -13,4 +13,4 @@
 
 vendor/
 
-image-output/
+output/

README.md

@@ -12,6 +12,10 @@ docker run lambda-php goodbye '{"name": "World"}'
 ../../bin/img2lambda -i docker-daemon:lambda-php:latest
 ```
 
+TODO:
+* Utility for creating a function deployment package from a Docker image
+* Support image types other than local Docker images ('docker-daemon' transport), where the layer format is tar. For example, layers directly from a Docker registry will be .tar.gz-formatted. OCI images can be either tar or tar.gz, based on the layer's media type.
+
 ## License Summary
 
 This sample code is made available under a modified MIT license. See the LICENSE file.

main.go

@@ -51,15 +51,15 @@ func createApp() (*cli.App, *cmdOptions) {
 		},
 		cli.BoolFlag{
 			Name:        "dry-run, d",
-			Usage:       "Conduct a dry-run: Repackage the image, but write the Lambda layers to local disk (do not publish to Lambda)",
+			Usage:       "Conduct a dry-run: Repackage the image, but only write the Lambda layers to local disk (do not publish to Lambda)",
 			Destination: &opts.dryRun,
 		},
 	}
 	return app, &opts
 }
 
 func repackImageAction(opts *cmdOptions) error {
-	return RepackImage(opts.image)
+	return RepackImage(opts.image, opts.outputDir)
 }
 
 func main() {

repack_image.go

@@ -13,8 +13,8 @@ import (
 	"github.com/pkg/errors"
 )
 
-// Converts container image to Lambda layers
-func RepackImage(imageName string) (retErr error) {
+// Converts container image to Lambda layer archive files
+func RepackImage(imageName string, layerOutputDir string) (retErr error) {
 	// Get image's layer data from image name
 	ref, err := alltransports.ParseImageName(imageName)
 	if err != nil {
@@ -49,11 +49,6 @@ func RepackImage(imageName string) (retErr error) {
 	layerInfos := src.LayerInfos()
 
 	// Unpack and inspect each image layer, copy relevant files to new Lambda layer
-	dir, err := os.Getwd()
-	if err != nil {
-		return err
-	}
-	layerOutputDir := filepath.Join(dir, "image-output", imageName)
 	if err := os.MkdirAll(layerOutputDir, 0777); err != nil {
 		return err
 	}

repack_layer.go

@@ -17,10 +17,6 @@ import (
 // Filters files from the source and only writes a new archive if at least
 // one file in the source matches the filter (i.e. does not create empty archives).
 func RepackLayer(outputFilename string, layerContents io.Reader) (created bool, retError error) {
-	// TODO: support image types other than local Docker images (docker-daemon transport),
-	// where the layer format is tar. For example, layers directly from a Docker registry
-	// will be .tar.gz-formatted. OCI images can be either tar or tar.gz, based on the
-	// layer's media type.
 	t := archiver.NewTar()
 
 	err := t.Open(layerContents, 0)