s3-image-optimizer

Optim

Automagitically optimize your images on S3 with the magic of AWS Lambda.

Optim is a super-simple Lambda function that can listen to an S3 bucket for uploads, and runs everything it can through imagemin.

Setup

• Clone this repo

• Run npm install

• Fill in AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY in .env to a set of credentials that can create Lambda functions (alternatively have these already in your environment)

• Create an IAM role for Optim to use. It needs the following permissions on all the S3 buckets you want to use (allowing these operations on ARN * is easiest to start with):

  • getObject
  • putObject
  • putObjectAcl

• Find the ARN for this role. It looks something like arn:aws:iam::1234567890:role/rolename.

• Fill in AWS_ROLE_ARN in .env

• Run npm run deploy

• Hurrah, your Lambda function is now deployed! It'll be created with the name optim-production unless you changed values in .env

• You can now hook this function up to any S3 bucket you like in the management console. Easiest way is to follow AWS's guide

Configuration

There are two sets of configuration here. The .env file contains configuration related to setup and deployment, and runtime.env is for configuration of how Optim behaves.

In .env:

• AWS_ACCESS_KEY_ID: the AWS access key used to deploy the Lambda function
• AWS_SECRET_ACCESS_KEY: the corresponding secret access key
• AWS_ROLE_ARN: role with which the lambda function will be executed
• AWS_REGION: which region to deploy to
• AWS_FUNCTION_NAME and AWS_ENVIRONMENT control naming of the lambda function created
• AWS_MEMORY_SIZE is the amount of memory given to your Lambda. It's also related to how much CPU share it gets. Since optimizing images is fairly intensive, probably best to keep this high
• AWS_TIMEOUT runtime timeout for the lambda in seconds up to 5 minutes. Again, image optimization is fairly intensive so you'll probably want to leave this at the maximum of 300.

In runtime.env:

• UPLOAD_ACL: finalised images will be uploaded with this permission level. Should be one of private public-read public-read-write aws-exec-read authenticated-read bucket-owner-read bucket-owner-full-control. Default is public-read.
• MAX_FILE_SIZE: files over this size in bytes will be skipped (e.g. big PNGs will probably just hit the timeout anyway). Set to -1 for no limit
• PNG_OPTIM_LEVEL: Optimization level to use for PNGs, between 0 and 7. Lower level means faster optimization, higher means better results.