Go V4 Signature in Lambda

As described in my post, this is a simple project that illustrates how to get Credentials from a session.Session so you can can create a v4.Signer and then sign a request all from within an AWS Lambda function.

Running Locally

This assumes that you AWS credentials configured locally and those credentials permit access to list S3 buckets.

go run cmd/signed/main.go

You should see an XML listing of all your S3 buckets.

Running as a Lambda

Create a zipped binary using the following command from the top of the project directory.

go build ./...
zip signed.zip signed

These are the basic steps to create the function using the console. If you're here, you probably already know how to do this, there's nothing special about this project.

1. Choose Create Function
2. Select Author from scratch
   • Function name: bucketlist
   • Runtime Go 1.x
3. Select Create Function
4. Select your signed.zip file after selecting the Upload button.
5. In the Handler field enter signed
6. Select the Save button in the top right.

The function doesn't expect any input so you can configure a simple test event (e.g. {}) and run the function by clicking the Test button. The function will succeed but the output will show that access was denied. You need to add the s3:ListAllMyBuckets policy action to your newly created role. Run the test again and you'll see the bucket list.