Lambda image resizer

What does this do

Takes an s3 object (let's use the term folder) and resizes and formats all the images it contains

• It only processes one level e.g. images in /quidco-images/banner/ will be processed, /quidco-images/banner/mobile won't be
• Creates a folder in the same directory for the resized images e.g. /quidco-images/banner/1100x250
• It will only resize an image to a specified dimension if the image is larger than the dimension e.g. if the specified dimensions are 1100x250 but the image size is 1000x100, that image will be skipped
• It will crop an image to fit the dimensions (instead of squeeze the image and make it look distorted) e.g. using the the dimensions 1100x250 as our target, it will resize a 1920x1080 image to a 1100x619 image and trim the the excess height evenly from both top and bottom to give us a final size of 1100x250

Running the application

Prerequisites

• Install golang https://golang.org/doc/install#install
• Install docker https://docs.docker.com/docker-for-mac/install/
• Pull the repo using go get github.com/mkadiri/lambda (recommended as this will place the project in the correct folder)

You should now find the project in ~/go/src/github.com/mkadiri/lambda-image-resizer

Use the Makefile

In the Makefile you'll find two commands make run and make zip

make run

The docker-compose has everything you need to run this application locally, however you'll need to specify your AWS credentials.

For testing purposes you'll need to create an s3 bucket with a folder, with images

The function name app as well as an event json will need to be passed.

The event json needs to specify the s3 bucket, s3 object (folder) and also the width and height you want to resize images to.

Note: make sure folder ends with a trailing slash

{
   "bucket": "quidco-images",
   "folder": "merchant-cover-photos/banners/",
   "width": 1100,
   "height": 250
 }

make zip

The application can be built and zipped with the make zip command, this zip file can be uploaded in to AWS

Resources

• s3 bucket: https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/s3-example-basic-bucket-operations.html