The AWS flow, end to end

Written by the Novosys Academy team · Explainer

When a user opens an app on AWS, the request passes through a chain of services. Each one has one job. Knowing the chain makes troubleshooting much faster.

The path, step by step

1. DNS turns the domain name into an address. In AWS this is often Route 53.
2. Load balancer receives the request and spreads it across healthy servers or containers.
3. Compute runs your code: EC2 instances, or containers on ECS or EKS.
4. Data is stored in a database such as RDS or DynamoDB, and files often sit in S3.
5. Logs and metrics go to CloudWatch, so you can see what happened.

Where the network fits

A VPC is your private network. Subnets split it. Public subnets reach the internet through an internet gateway. Private subnets keep databases off the public internet. Security groups act as firewalls around each resource.

Who is allowed to do what

IAM controls identities. Users and roles get policies that list what they may do. Applications should use roles rather than stored keys. Give each one the smallest set of permissions it needs.

Following a request when it fails

• Did the domain resolve? Check DNS first.
• Did the load balancer see the request? Check its metrics and target health.
• Did the instance or container answer? Check its logs.
• Did the database accept the connection? Check the security group and the credentials.

Work through the chain in order. Most problems show up at one of these five points.