More README details + logging

Author: clareliguori

README.md

@@ -1,23 +1,83 @@
 ## AWS Lambda Container Image Converter
 
-This container image converter tool (img2lambda) repackages container images (such as Docker images) into AWS Lambda layers, and publishes them as new layer versions.
+This container image converter tool (img2lambda) repackages container images (such as Docker images) into AWS Lambda layers, and publishes them as new layer versions to Lambda.  The tool copies all files under '/opt' in the Docker image, maintaining the individual Docker image layers as individual Lambda layers.  The published layer ARNs will be stored in a file 'output/layers.json', which can be used as input when creating Lambda functions.
 
 ```
+USAGE:
+   img2lambda [options]
+
+GLOBAL OPTIONS:
+   --image value, -i value             Name of the source container image. For example, 'my-docker-image:latest'
+   --region value, -r value            AWS region (default: "us-east-1")
+   --output-directory value, -o value  Destination directory for command output (default: "./output")
+   --layer-namespace value, -n value   Prefix for the layers published to Lambda (default: "img2lambda")
+   --dry-run, -d                       Conduct a dry-run: Repackage the image, but only write the Lambda layers to local disk (do not publish to Lambda)
+   --help, -h                          show help
+```
+
+## Build
+
+```
+go get -t -v ./...
+```
+
+## Example
+
+Build the example Docker image to create a PHP Lambda custom runtime:
+```
+cd example
+
 docker build -t lambda-php .
+```
 
+The example PHP functions are also built into the example image, so they can be run with Docker:
+```
 docker run lambda-php hello '{"name": "World"}'
 
 docker run lambda-php goodbye '{"name": "World"}'
+```
+
+Run the tool to create and publish Lambda layers that contain the PHP custom runtime:
+```
+../../../bin/img2lambda -i lambda-php:latest -r us-east-1
+```
+
+Create a PHP function that uses the layers:
+```
+cd function
 
-../../bin/img2lambda -i docker-daemon:lambda-php:latest
+zip hello.zip src/hello.php
+
+aws lambda create-function \
+    --function-name php-example-hello \
+    --handler hello \
+    --zip-file fileb://./hello.zip \
+    --runtime provided \
+    --role "arn:aws:iam::XXXXXXXXXXXX:role/service-role/LambdaPhpExample" \
+    --region us-east-1 \
+    --layers file://../output/layers.json
+```
+
+Finally, invoke the function:
 ```
+aws lambda invoke \
+    --function-name php-example-hello \
+    --region us-east-1 \
+    --log-type Tail \
+    --query 'LogResult' \
+    --output text \
+    --payload '{"name": "World"}' hello-output.txt | base64 --decode
+
+cat hello-output.txt
+```
+
+## TODO
 
-TODO:
 * Support image types other than local Docker images, 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.
 * De-dupe Lambda layers before publishing them (compare local file's SHA256 to published layer versions with the same name)
 * Accept additional parameters for PublishLayerVersion API (license, description, etc)
 * Support Lambda compatible runtimes other than 'provided'
-* Utility for creating a function deployment package from a Docker image
+* Utility for creating a function deployment package from a Docker image (copying from /var/task/src instead of /opt)
 
 ## License Summary
 

publish_layers.go

@@ -3,6 +3,7 @@ package main
 import (
 	"encoding/json"
 	"io/ioutil"
+	"log"
 	"os"
 	"path/filepath"
 	"strings"
@@ -47,6 +48,8 @@ func PublishLambdaLayers(sourceImageName string, layers []LambdaLayer, region st
 		if err != nil {
 			return err
 		}
+
+		log.Printf("Published Lambda layer file %s (image layer %s) to Lambda: %s", layer.File, layer.Digest, *resp.LayerVersionArn)
 	}
 
 	jsonArns, err := json.MarshalIndent(layerArns, "", "  ")
@@ -66,5 +69,7 @@ func PublishLambdaLayers(sourceImageName string, layers []LambdaLayer, region st
 		return err
 	}
 
+	log.Printf("Lambda layer ARNs (%d total) are written to %s", len(layerArns), resultsPath)
+
 	return nil
 }

repack_image.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 
@@ -20,6 +21,8 @@ type LambdaLayer struct {
 
 // Converts container image to Lambda layer archive files
 func RepackImage(imageName string, layerOutputDir string) (layers []LambdaLayer, retErr error) {
+	log.Printf("Parsing the docker image %s", imageName)
+
 	// Get image's layer data from image name
 	ref, err := alltransports.ParseImageName(imageName)
 	if err != nil {
@@ -53,6 +56,8 @@ func RepackImage(imageName string, layerOutputDir string) (layers []LambdaLayer,
 
 	layerInfos := src.LayerInfos()
 
+	log.Printf("Image %s has %d layers", imageName, len(layerInfos))
+
 	// Unpack and inspect each image layer, copy relevant files to new Lambda layer
 	if err := os.MkdirAll(layerOutputDir, 0777); err != nil {
 		return nil, err
@@ -75,10 +80,15 @@ func RepackImage(imageName string, layerOutputDir string) (layers []LambdaLayer,
 		}
 
 		if fileCreated {
+			log.Printf("Created Lambda layer file %s from image layer %s", lambdaLayerFilename, string(layerInfo.Digest))
 			lambdaLayerNum++
 			layers = append(layers, LambdaLayer{Digest: string(layerInfo.Digest), File: lambdaLayerFilename})
+		} else {
+			log.Printf("Did not create a Lambda layer file from image layer %s (no relevant files found)", string(layerInfo.Digest))
 		}
 	}
 
+	log.Printf("Created %d Lambda layer files for image %s", len(layers), imageName)
+
 	return layers, nil
 }