AWS in Action: Lambda
This repository demonstrates how you can create a bunch of resized images right after uploading an image to S3. The solution requires no servers, is scalable and can be automatically deployed within minutes. The following figure demonstrate the image resizing process.
The solution makes use of two S3 buckets:
- The bucket that contains the original images. Users upload images to this bucket. This bucket is suffixed with
-original
in the following example. - The bucket that contains the resized images. The bucket is suffixed with
-resized
in the following example.
When you upload an image to the -original
bucket a Lambda function is executed. The Lambda function downloads the image from S3, creates multiple resized versions and uploads them to the -resized
S3 bucket. As of now three resized copies are created for every upload to -original
:
150x
fixed width, height is scaled as needed50x50
scale image best into boxx150
fixed height, width is scaled as needed
You can find out how ImageMagick resize works or read on to deploy the solution.
Deploying the solution
==WARNING: This example assumes that you have installed and configured the AWS Command Line Interface==
Clone this repository ...
$ git clone [email protected]:AWSinAction/lambda.git
$ cd lambda/
or download and extract the zipped repository.
$ wget https://github.com/AWSinAction/lambda/archive/master.zip
$ unzip master.zip
$ cd lambda-master/
Create an S3 bucket for your Lambda code in the US East (N. Virginia, us-east-1
) region and upload the lambda.zip
file (replace $LambdaS3Bucket
with a S3 bucket name e.g. lambda-michael
).
==WARNING: This bucket has nothing to do with the resizing of images. It contains the zipped source code of the Lambda function.==
export AWS_DEFAULT_REGION=us-east-1
$ aws s3 mb s3://$LambdaS3Bucket
$ aws s3 cp lambda.zip s3://$LambdaS3Bucket/lambda.zip
Create a CloudFormation stack (replace $ImageS3Bucket
with a name for your image bucket e. g. image-michael
, replace $LambdaS3Bucket
with your Lambda code S3 bucket name).
$ aws cloudformation create-stack --stack-name lambda-resize --template-body file://template.json --capabilities CAPABILITY_IAM --parameters ParameterKey=ImageS3Bucket,ParameterValue=$ImageS3Bucket ParameterKey=LambdaS3Bucket,ParameterValue=$LambdaS3Bucket
Wait until the stack is created (retry if you get CREATE_IN_PROGRESS
this can take a few minutes).
$ aws cloudformation describe-stacks --stack-name lambda-resize --query Stacks[].StackStatus
[
"CREATE_COMPLETE"
]
You can now upload your first image to the -original
S3 bucket (you can also use the web based Management Console if you prefer).
$ aws s3 cp path/to/image.png s3://$ImageS3Bucket-original/image.png
You will see the resized images in the -resized
bucket (you can also use the web based Management Console if you prefer).
$ aws s3 ls s3://$ImageS3Bucket-resized
PRE 150x/
PRE 50x50/
PRE x150/
$ aws s3 ls s3://$ImageS3Bucket-resized/150x/
As you can see, for every size configuration a new "directory" was created.
What's next?
From this point you can think about how to enable your users to upload files into the -original
S3 bucket if your use cases requires user generated content. To allow uploads from your users you should think about a way to protect your -original
bucket with IAM permissions. You could use the Security Token Service to achieve this.
You should use CloudFront in combination with the -resized
bucket to serve the resized images to your end users. This will decrease the latency by pushing your content to one of the edge locations of the CloudFront CDN network.
Teardown
Remove all files in the -original
and -resized
bucket.
$ aws s3 rm --recursive s3://$ImageS3Bucket-original
$ aws s3 rm --recursive s3://$ImageS3Bucket-resized
Delete the CloudFormation stack.
$ aws cloudformation delete-stack --stack-name lambda-resize
Delete Lambda code S3 bucket (replace $LambdaS3Bucket
).
$ aws s3 rb --force s3://$LambdaS3Bucket
Customize the code
If you want to make changes to the code you need to create a new lambda code file (lambda.zip
) and upload the new zip to S3. You can adjust the config.json
file to adjust the size configurations.
$ npm install
$ ./bundle.sh
$ aws s3 cp lambda.zip s3://$LambdaS3Bucket/lambda.zip
Summary
AWS Lambda can respond to S3 events like a new file was uploaded. The Lambda function will download the original image from S3 to create new resized images. The resized images are then upload to S3 again. The Lambda solution in scalable and does not require any operational work.