aws-lambda-image-resizer

AWS Lambda image resizer function written in Go

Create buckets

Open the S3 management console and create two buckets, one for the source images and one for the resized images:

Important: S3 bucket names have to be globally unique!

Create policy

Open the IAM managment console and create a new policy:

Create role

Create a new role. For use case, select Lambda. Click on next and select the policy from the previous step:

Build the lambda function

$ go build resizer.go
$ zip resizer.zip resizer

This creates an archive with the resizer binary that can be uploaded as lambda function to AWS.

Create lambda function

Open the Lambda managment console and create a new function:

This takes some time. After the function is created, the following screen shold be shown:

Select Upload from on the right-hand side of Code source and upload the resizer.zip archive. Next edit the Runtime settings and change the name of the handler to resizer.

Next we need to configure a trigger so that the image resizer function is called when an image is uploaded to the source bucket. Click on Configuration and select Triggers, then Add trigger:

We also need to add an environment variable for the destination bucket used to store the resized images:

Try it

Open the S3 management console and upload an image to the source bucket:

The image resizer function should now be executed automatically and create a resized image in the destination bucket: