For example, currently my application runs on EC2/Lambda and I have IAM policies defined on the resources that let me authorize and interact with other AWS services. What would that look like if I moved my applications to Fly.io?
Since Fly is outside AWS you would need to create a user within the AWS console. You attach to that user the IAM policies your EC2/Lambda role has. So that user would have the same access to your AWS resources
Creating that user (with programmatic access) will give you these values you will need:
You would then set those as secrets within Fly so they are safely encrypted Secrets and Fly Apps · Fly