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Classic Architecture Discussion

  • This section discusses basic architectural solutions combining technical offerings provided by AWS

Stateless Web Apps: WhatIsTheTime.com

  • WhatIsTheTime.com: allows people to know what time it is

  • No database required

  • We want to start small and can accept downtime at the beginning

  • We want to be able to fully scale vertically and horizontally with no downtime

  • Considerations when building the architecture:

    • Public IP vs private IP in case of EC2 instances
    • Elastic IP vs Route53 vs Load Balancers
    • Route53 TTL A records vs Alias Records
    • Maintaining EC2 instance scaling manually vs using an ASG
    • Multi AZ deployments to have disaster recovery
    • ELB Heath Checks
    • Security Groups Rules
    • Reservation of capacity for cost saving when possible
    • We are considering the 5 pillars of a well architected application: cost, performance, reliability, security and operational excellence

Stateful Web Apps: MyClothes.com

  • MyClothes.com: allows people to buy clothes online

  • There is a shopping cart for every user

  • The application can have hundreds of users using the app in the same time

  • We need to scale, maintain horizontal scalability and keep the app as stateless as possible

  • Users should not loose their shopping cart while navigating the site

  • Users should have their details in a database

  • Consideration when building the architecture:

    • ELB sticky sessions
    • Web clients for storing cookies and making the application stateless
    • Session id + session cache which can be ElastiCache or DynamoDB
    • ElastiCache can be used to cache data from RDS
    • Multi AZ for disaster recovery
    • RDS:
      • We can use it for store user data
      • We can have read replicas for scaling reads
      • We can enable Multi AZ for disaster recovery

  • Tight security using security groups

Instantiating Applications Quickly

  • When launching a full stack application, it can take time to:
    • Install the application
    • Insert initial (or recovery) data
    • Configure everything
    • Launch the application
  • In order to solve this we can use:
    • For EC2 Instances:
      • Golden AMI: install the application, OS, dependencies etc. beforehand and launch the EC2 instance from the Golden AMI
      • Bootstrap using User Data: for dynamic configuration we can use User Data scripts
    • For RDS databases we can restore the database from a snapshot
    • For EBS Volumes we can also restore the data from a snapshot