I can't figure out how to make them talk using API calls. Previously I used API Gateways which would trigger lambdas and that lambdas would interact with dynamodb and other services and send me back json response. Now I want to shift to EC2 instances and totally skip API gateway usage. And let a server I run in ec2 do the computation for me. Do I need to deploy a web service(DJango RESTFUL) in EC2 instance and then use it to call in my frontend? If yes I need little guidance how And Suppose I want to access s3 storage from my DJango restufl in EC2. Can I do it without having to enter the access key and ID and use roles instead just like how I would access s3 from the ec2 instance without access key and ID. Traditionally with SDK we have to use access key and secret keys to even get authorized to use services in SDK so I was wondering if there was a way to get over this since the program will be running in EC2 instance itself. One really inefficient way will be to run a batch command that makes the EC2 interact with services I need without SDK and with roles instead but It is really inefficient and too much work as far as I can see.
As you are familiar with API Gateway, you can use the same to connect to your EC2 instance, its private integration, with the use of VPC Links.
You can create an API Gateway API with private integration to provide your customers access to HTTP/HTTPS resources within your Amazon Virtual Private Cloud (Amazon VPC). Such VPC resources are HTTP/HTTPS endpoints on an EC2 instance behind a Network Load Balancer in the VPC.
You can go though this document for step by step integration.
If you do not want to use API gateway any more, then you can simply use Route53 to route traffic to EC2 instance, all you need is the IP address of the EC2 instance and a hosted zone created using Route53.
Here is a tutorial for your reference.