aws-lambda-image

An AWS Lambda Function to resize/reduce images automatically. When an image is put on AWS S3 bucket, this package will resize/reduce it and put to S3.

Requirements

• node.js ( AWS Lambda working version is 4.3.2 )

Installation

Clone this repository and install dependencies:

$ git clone https://github.com/itinerantfoodie/aws-lambda-image.git
$ cd aws-lambda-image
$ npm install .

When upload to AWS Lambda, the project will bundle only needed files - no dev dependencies will be included.

Configuration

Configuration file you will find under the name config.json in project root. It's copy of our example file config.json.sample. More or less it looks like:

{
  "bucket": "your-destination-bucket",
  "backup": {
      "directory": "./original"
  },
  "reduce": {
      "directory": "./reduced",
      "prefix": "reduced-",
      "quality": 90,
      "acl": "public-read"
  },
  "resizes": [
    {
      "size": 300,
      "directory": "./resized/small",
      "prefix": "resized-"
    },
    {
      "size": 450,
      "directory": "./resized/medium",
      "suffix": "_medium"
    },
    {
      "size": "600x600^",
      "gravity": "Center",
      "crop": "600x600",
      "directory": "./resized/cropped-to-square"
    },
    {
      "size": 600,
      "directory": "./resized/600-jpeg",
      "format": "jpg",
      "background": "white"
    },
    {
      "size": 900,
      "directory": "./resized/large",
      "quality": 90
    }
  ]
}

Configuration Parameters

name	field	type	description
bucket	-	String	Destination bucket name at S3 to put processed image. If not supplied, it will use same bucket of event source.
backup	-	Object	Backup original file setting.
	directory	String	Image directory path. When starts with ./ relative to the source, otherwise creates a new tree.
	bucket	String	Destination bucket to override. If not supplied, it will use bucket setting.
reduce	-	Object	Reduce setting following fields.
	directory	String	Image directory path. When starts with ./ relative to the source, otherwise creates a new tree.
	prefix	String	Append filename prefix if supplied.
	suffix	String	Append filename suffix if supplied.
	quality	Number	Determine reduced image quality ( enables only JPG ).
	bucket	String	Destination bucket to override. If not supplied, it will use bucket setting.
	acl	String	Permission of S3 object. See acl values.
resize	-	Array	Resize setting list of following fields.
	background	String	Background color to use for transparent pixels when destination image doesn't support transparency.
	bucket	String	Destination bucket to override. If not supplied, it will use bucket setting.
	crop	String	Dimensions to crop the image. See ImageMagick crop documentation.
	directory	String	Image directory path. When starts with ./ relative to the source, otherwise creates a new tree.
	prefix	String	Append filename prefix if supplied.
	suffix	String	Append filename suffix if supplied.
	gravity	String	Changes how size and crop. See ImageMagick gravity documentation.
	quality	Number	Determine reduced image quality ( forces format JPG ).
	format	String	Image format override. If not supplied, it will leave the image in original format.
	size	String	Image dimensions. See ImageMagick geometry documentation.
	orientation	Boolean	Auto orientation if value is true.
	acl	String	Permission of S3 object. See acl values.

Testing Configuration

If you want to check how your configuration will work, you can use:

$ npm run test-config

Installation

Preparations

To use the automated deployment scripts you will need to have aws-cli installed and configured.

Deployment scripts are pre-configured to use some default values for the Lambda configuration. I you want to change any of those just use:

$ npm config set aws-lambda-image:profile default
$ npm config set aws-lambda-image:region eu-west-1
$ npm config set aws-lambda-image:memory 1280
$ npm config set aws-lambda-image:timeout 5

Deployment

Command below will deploy the Lambda function on AWS, together with setting up roles and policies.

$ npm run deploy

Notice: Because there are some limitations in Claudia.js support for policies, which could lead to issues with Access Denied when processing images from one bucket and saving them to another, we have decided to introduce support for custom policies.

Custom policies

Policies which should be installed together with our Lambda function are stored in policies/ directory. We keep there policy that grants access to all buckets, which is preventing possible errors with Access Denied described above. If you have any security-related concerns, feel free to change the:

"Resource": [
    "*"
]

in the policies/s3-bucket-full-access.json to something more restrictive, like:

"Resource": [
    "arn:aws:s3:::destination-bucket-name/*"
]

Just keep in mind, that you need to make those changes before you do the deployment.

Adding S3 event handlers

To complete installation process you will need to take one more action. It will allow you to install S3 Bucket event handler, which will send information about all uploaded images directly to your Lambda function.

$ npm run add-s3-handler --s3_bucket="your-bucket-name" --s3_prefix="directory/" --s3_suffix=".jpg"

Note: Unfortunately, for now Clauda.js is able to install only one such handler per Bucket. This issue has been already raised and hopefully will be fixed soon.

Updating

To update Lambda with you latest code just use command below. Script will build new package and automatically publish it on AWS.

$ npm run update

More

For more scripts look into package.json.

Complete / Failed hooks

You can handle resize/reduce/backup process on success/error result on index.js. ImageProcessor::run will return Promise object, run your original code:

processor.run(config)
.then(function(proceedImages)) {

    // Success case:
    // proceedImages is list of ImageData instance on you configuration

    /* your code here */

    // notify lambda
    context.succeed("OK, numbers of " + proceedImages.length + " images has proceeded.");
})
.catch(function(messages) {

    // Failed case:
    // messages is list of string on error messages

    /* your code here */

    // notify lambda
    context.fail("Woops, image process failed: " + messages);
});

Image resize

• ImageMagick (installed on AWS Lambda)

Image reduce

• cjpeg
• pngquant
• gifsicle

License

MIT License.

Author

Yoshiaki Sugimoto

Image credits

Thanks for testing fixture images:

• http://pngimg.com/
• https://www.pakutaso.com/