More Solution Architecture

Event Processing

• SQS + Lambda:
  • Lambda functions pulls the SQS queue, in case there is a problem, the message is put back onto the queue for reprocessing
  • To avoid endless loops in processing, we can set up a deal-letter queue (DLQ)
• SQS FIFO + Lambda:
  • If a message is not processed, it can block the whole queue
  • In order to get around this, we can also set up a DLQ
• SNS + Lambda:
  • In case a message is not processed, the Lambda will retry 3 times
  • We can also set up a DLQ at the Lambda service level
• Fan Out Pattern:
  • Deliver messages to multiple SQS queues
  • In order to achieve this, we can create an SNS topic and create SQS queue subscribers
  • We can combine Fan Out pattern with S3 events
  • We can also create filter to filter out some events and react to only what is needed
  • We can create as many S3 events as we want
  • If two events are happening on the same object on the same time, there is a possibility that only one event notification is sent. To overcome this we can use versioning

Caching Strategies

• CloudFront: caching happens globally as close as possible to the users
• API Gateway: offers regional caching
• Redis, Memcached, DAX: caching is closer to the application. The reason for this is to avoid load on a database

Blocking an IP Address in AWS

• Network ACL, VPC level: create a deny rule
• Security Groups: define a subset of IP which can access the application
• Optional firewall installed on the instance
• In case of an Application Load Balancer:
  • ALB does connection termination, from the EC2 side we just have to approve traffic from the ALB
  • In the SG of the LB we can specify from where the traffic can came from
  • We can also install WAF on the ALB, where we can do some complex filtering
• In case of Network Load Balancer:
  • NLB does not do connection termination, there is no such thing as a SG for the NLB
• In case of CloudFront:
  • CloudFront seats outside of a VPC, so we can not set NACL rules
  • In this case to block a client on CloudFront, we can do the following:
    • Use georestriction to restrict the country from where traffic is coming from
    • Use WAF IP Address filtering on the CloudFront distribution

High Performance Computing (HPC)

• The cloud is the perfect place to perform HPC
• We can use HPC to perform genomics, computational chemistry, financial risk modeling, weather prediction, machine learning, deep learning, etc.
• Data Management and Transfer:
  • AWS Direct Connect: move GB of data to the cloud over private secure network
  • Snowball and Snowmobile: move PB of data to the cloud
  • AWS DataSync: move large amount of data between on-premise and S3, EFS, FSx
• Compute and Networking:
  • EC2 Instances:
    • CPU optimized and GPU optimized
    • Spot instances/spot fleets for cost saving + auto scaling
  • EC2 Placement Groups:
    • Cluster placement group for good network performance
  • EC2 Enhanced Networking (SR-IOV):
    • Higher bandwidth, higher packet per second, lower latency
    • How to get Enhanced Networking:
      • Option 1: Elastic Network Adapter (ENA) up to 100 Gbps
      • Option 2: Intel 82599 VF up to 10 GBps - Legacy
  • Elastic Fabric Adapter (EFA)
    • Improved ENA for HPC, only works for Linux
    • Great for inter-node communications, tightly coupled workflows
    • Leverages Message Passing Interface (MPI) standards
    • Bypasses the underlying Linux OS to provide low-latency, reliable transport
• Storage:
  • Instance-attached storage:
    • EBS: scales up to 64000 IOPS with io1 Provisioned IOPS
    • Instance Store: scales to millions of IOPS, linked to EC2 instance, low latency
  • Network storage:
    • S3: for large blobs
    • EFS: scale IOPS based on total size or we can use provisioned IOPS
    • FSx for Lustre: HPC optimized distributed file system, provides millions of IOPS, backed by S3
• Automation and orchestration:
  • AWS Batch:
    • Supports multi-node parallel jobs, which enables to run single jobs that can span across multiple EC2 instances
    • We can easily schedule jobs and launch EC2 instances accordingly
  • AWS ParallelCluster:
    • Open source cluster management tools to deploy HPC on AWS
    • It is configured with text files
    • Automate creation of VPC, Subnet, cluster type and instance types

Highly Available EC2 Instances

1. Option:
   • Main EC2 instance with Elastic IP + standby EC2 instance for failover
   • EC2 instance can be monitored with CloudWatch Events + Lambda functions. Using this method we can failover in case of an issue.
2. Option:
   • ASG in 2 availability zones
   • ASG settings: 1 min, 1 max, 1 desired
   • In case of failover the new instance will be launched in the second AZ
   • The Elastic IP can be attached to the instance with using an user data script
3. Option:
   • Setup is same as option 2 + EBS
   • ASG can use lifecycle groups, based on these we can create an EBS snapshot and attach it to the newer instance

Highly Available Bastion Hosts

• Bastion hosts can be created in multiple subnet, same VPC
• We can create a Network Load Balancer which can route traffic to multiple bastion hosts