Serverless Overview

Serverless

• 개발자가 서버를 관리할 필요 없이 어플리케이션을 빌드하고 실행할 수 있도록 하는 것
  • 서버가 없다는 것 X
• Severless was pioneered by AWS Lambda, but now also includes anything that's managed

Serverless in AWS

• AWS Lambda
  • Virtual functions - no servers to manage
  • Limited by time - short executions
  • Run on-demand
  • Scaling is automated
  • Benefits of AWS Lambda
    • Easy Pricing
      • Pay per request and compute time ($0.20 per 1 million requests thereafter)
      • Free tier of 1,000,000 AWS Lambda requests and 400,000 GBs of compute time
      • very cheap to run
    • Integrated with the whole AWS suite of services
    • Integrated with many programming languages
    • Easy monitoring through AWS CloudWatch
    • Easy to get more resources per functions
    • Increasing RAM will also improve CPU and network
    • Lambda SnapStart
      • Improves Lambda functions performace up to 10x at no extra cost for Java 11 and above
      • When enabled, function is invoked from a pre-initialized state
      • When  you publish a new version:
        • Lambda initializes your function
        • Takes a snapshot of memory and disk state of the initialized function
        • Snapshot is cached for low-latency access 
    • Customization At The Edge
      • Many modern applications execute some form of the logic at the edge
      • Edge Function 
        • A code that you write and attach to CloudFront distributions
        • Runs close to your users to minimized latency
      • CloudFront provides two types :
        • CloudFront Functions
          • Cache Key normalization
          • Header manipulation
          • URL rewrites or redirects
          • Request authentication & authorization
        • Lambda@Edge
          • Longer execution time
          • Adjustable CPU or memory
          • Code depends on a 3rd libraries
          • Network access to use external services for processing
          • File System access or access to the body of HTTP requests
        • Use Case :
          • Website Security and Privacy
          • Dynamic Web Application at the Edge
          • Search Engine Optimization
          • Intelligently Route Across Origins and Data Centers
          • Bot Migration at the Edge
          • Real-time Image Transformation
          • A/B Testing
          • User Authentication and Authorization
          • User Prioritization
          • User Tracking and Analytics
      • You don't have to manage any servers, deployed globally
      • Use case
        • customize the CDN content
      • Pay only for what you use
      • Fully severless
      • Lambda by default
        • launched outside your own VPC
        • cannot access resources in your VPC
      • Lambda in VPC
        • must define the VPC ID, the Subnets and the Security Groups
        • will create an ENI in your subnets
      • Lambda with RDS Proxy
        • If Lambda functions directly access your database, they may open too many connections under high load
        • RDS Proxy
          • Improve scalability by pooling and sharing DB connections
          • Improve availability by reducing by 66% the failover time and preserving connections
          • Improve security by enforcing IAM authentication and storing credentials in Secrets Manager
        • The Lambda function must be deployed in yourVPC, because RDS Proxy is never publicly accessible
      • Invoking Lambda from RDS & Aurora
        • Invoke Lambda functions from within your DB instance
        • Allow you to process data events from within a database
        • Supported for RDS for PostgreSQL and Aurora MySQL
        • Must allow outbound traffic to your Lambda function from within your DB instances
        • DB instance must have the required permissions to invoke the Lambda function
      • RDS Event Notifications
        • Notifications that tells information about the DB instance itself
        • You don't have any information about the data itself
        • Subscribe to the following event categories 
          • DB instance
          • DB snapshot
          • DB Parameter Group
          • DB security Group
          • RDS Proxy
          • Custom Engine Version
        • Near real-time events
        • Send notifications to SNS or subscribe to events using EventBridge
• Dynamo DB
  • Fully managed, highly available with replication across multiple AZs
  • NoSQL db with transaction support
  • Scales to massive workloads, distributed db
  • Millions of requests per seconds, thrillions of row, 100s of TB of storage
  • Fast and consistent in performance
  • Integrated with IAM for security, authorization and administration
  • Low cost and auto-scaling capabilites
  • No maintenance or patching, always available
  • Standard & Infrequent Access Table Class
  • Basics
    • DyanamoDB is made of table
    • Each table has a Primary Key (must be decided at creation time)
    • Each table can have an infinite number of items
    • Each item has attributes (can be added over time - can be null)
    • Maximum size of an item is 400KB
    • Data types supported are :
      • Scalar Types
      • Document Types
      • Set Types
    • DynamoDB can rapidly evolve schemas
  • Read/Write Capacity Modes
    • Provisioned Mode (default)
      • You specify the number of reads/writes per second
      • You need to plan capacity beforehand
      • Pay for provisioned Read Capacity Units & Write Capactiy Units
      • Possibility to add auto-scaling mode for RCU & WCU
    • On-Demand Mode
      • Read/writes automatically scale up/down with your workloads
      • No capacity planning needed
      • Pay for what you use, more expensive
      • Greate for unpredictable, workloads, steep sudden spikes
  • DynamoDB Accelerator
    • Fully-managed, highly available, seamless in-memory cache for DynamoDB
    • Help solve read congestion by caching
    • Microseconds latency for cached data
    • Doesn't require application logic modification (compatible with existing DynamoDB APIs)
    • 5 minutes TTL for cache
  • Stream Processing
    • Ordered stream of item-level modifications in a table
    • 24 hours retention
    • Limited # of consumers
    • Process using AWS Lambda Triggers, or DynamoDB Stream Kinesis adapter
    • Use Case :
      • React to changes in real-time
      • Real-time usage analytics
      • Insert into derivative tables
      • Implement cross-region replication
      • Invoke AWS Lambda on changes to your Dynamo DB table
  • DynamoDB Global Tables
    • Make a DynamoDB table accessible with low latency in multiple-regions
    • Active-Active replication
    • Applications can READ and WRITE to the table in any region
    • Must enable DynamoDB Streams as a pre-requisite
  • Time to Live
    • Automatically delete items after an expiry timestamp
    • Use cases :
      • reduace stored data by keeping only current items
      • adhere to regulatory obligations
      • web session handling
  • Backups for disaster recovery
    • Continuous backups using point-in-time recovery
      • Optionally enabled for the last 35 days
      • Point-in-time recovery to any time within the backup window
      • The recovery process creates a new table 
    • On-demand backups
      • Full backups for long-term retention, until explicitely deleted
      • Doesn't affect performance or latency
      • Can be configured and managed in AWS Backup (enable cross-region copy)
      • They recovery process creates a new table
  • Integration with Amazon S3
    • Export to S3 (must enable PITR)
      • Works for any point of time in the last 35 days
      • Doesn't affect the read capacity of your table
      • Perform data analysis on top of DynamoDB
      • Retain snapshots for auditing
      • ETL on top of S3 data before importing back into DynamoDB
      • Export in DynamoDB JSON or ION format
    • Import from S3
      • import CSV, DynamoDB JSON or ION format
      • Doesn't consume any write capacity
      • Creates a new table
      • Import errors are logged in CloudWatch Logs

• AWS Coginto
  • Give users an identity to interact with our web or mobile application
  • Coginto User Pools
    • Create a serverless database of user for your web & mobile apps
    • CUP integrates with API Gateway and Appliction Load Balancer
  • Coginto Identity Pools
    
    • Get identities for "users" so they obtain temporary AWS credentials
    • Users can then access AWS services directly or through API Gateway
    • The IAM policies applied to the credentials are defined in Cognito
    • They can be customized based on the user_id for fine grained control
    • Default IAM roles for authenticated and guest users
• AWS API Gateway
  • AWS Lambda + API Gateway 
    • No infrastructure to manage
  • Integrations High Level
    • Lambda Function
      • Invoke Lambda function
      • Easy way to expose REST API backed by AWS Lambda
    • HTTP
      • Expose HTTP endpoints in the backend
      • Use Case:
        • Internal HTTP API on premise
        • Application Load Balancer
    • AWS Service
      • Expose any AWS API through the API Gateway
      • Use Case :
        • start an AWS Step Function workflow
        • post a message to SQS
  • Endpoint Types
    • Edge-Optimized : for global clients
      • Requests are routed through the CloudFront Edge locations (improve latency)
      • The API Gateway still lives in only one region
    • Regional : for clients within the same reigon
      • could manually combine with CloudFront
        • more control over the caching strategies and the distribution
    • Private
      • can only be accessed from your VPC using an interface VPC endpoint
      • use a resource policy to define access
  • Support for the WebSocket Protocol
  • Handle API versioning
  • Handle different environments
  • Handle security
    • User Authentication through
      • IAM Roles (internal applications)
      • Coginto(external users)
      • Custom Authorizer(own logic)
    • Custom Domain Name HTTPS security through integration with AWS Certificate Manger
      • If using Edge-Optimized endpoint, then the certificate must be in us-east-1
      • If using Regional endpoint, the certificate must be in the API Gateway region
      • Must setup CNAME or A-alias record in Route 53
  • Create API keys, handle request throttling
  • Swagger / Open API import to quickly define APIs
  • Transform and validate requests and responses
  • Generate SDK and API specifications
  • Cache API responses
• Amazon S3
• AWS SNS & SQS
• AWS Kinesis Data Firehose
• Aurora Serverless
• Step Functions
  • Build serverless visual workflow to orchestrate your Lambda functions
  • Features : sequence, parallel, conditions, timeouts, error handling ...
  • Can integrate with EC2, ECS, On-premises servers, API Gateway, SQS queues ...
  • Posiibility of implementing human approval feature
  • Use cases : 
    • order fulfillment
    • data processing
    • web applications
    • any workflow
• Fargate