Section 7 - Serverless

Question 1

What is Serverless Computing?

Answer 1

Serverless is a way to describe the services, practices, and strategies that enable you to build more agile applications so you can innovate and respond to change faster.

With serverless computing, infrastructure management tasks like capacity provisioning and patching are handled by AWS, so you can focus on only writing code that serves your customers. Serverless services like AWS Lambda come with automatic scaling, built-in high availability, and a pay-for-value billing model.

Lambda is an event-driven compute service that enables you to run code in response to events from over 200 natively-integrated AWS and SaaS sources - all without managing any servers.

• Move from idea to market, faster
• Low infrastructure costs.
• Usage based cost.
• Scalability and reliability.

Question 2

What are examples of Serverless Technologies?

Answer 2

• Lambda
  
  • Enables you to run code as functions without provisioning any servers
• SQS (Simple Queue Service)
  
  • A message queueing service that allows you to decouple and scale your applications
• SNS (Simple Notification Service)
  
  • A messaging service for sending text messages, mobile notifications and emails.
• API Gateway
  
  • Allows you to create, publish, and secure APIs at any scale
• DynamoDB
  
  • Fully managed NoSQL database.
• S3
  
  • Object storage and web hosting.

Question 3

Current AWS Lambda characterics?

Answer 3

• Execution time 15 minutes (Hard limit)
• 1000 executions at a time
• Enviroment variables 4 KB
• Parameter limit on Syncronous process 64 MB
• Parameter limit on Asyncronous process 256 KB
• The first 1 million requests per month are free.
• 20 cents per 1 million requests

Question 4

AWS services that can invoke Lambda functions

Answer 4

Lambda Triggers:

• DynamoDB
• Kinesis
• SQS
• Application Load Balancer
• API Gateway
• Alexa
• CloudFront
• S3
• SNS
• SES
• CloudFormation
• CouldWatch
• CodeCommit
• CodePipeLine

https://docs.aws.amazon.com/lambda/latest/dg/lambda-services.html

Question 5

AWS Lambda Versioning?

Answer 5

• When you create a Lambda function, there is only one version $LATEST
• When you upload a new version of your code to Lambda, this version will become $LATEST
• You can create multiple versions of your function code and use aliases to reference the version you want to use as part of the ARN

Question 6

AWS Lambda concurrent executions limit?

Answer 6

Concurent Executions:

• Default is 1,000 concurrent executions per second per region (You can make a request to increase via AWS Support Center)
• TooManyRequestsException
• HTTP Status Code: 429
• Request throughput limit exceeded
• Reserved concurrency guarantees that a set number of executions which will always be available for your critical function, however this also acts as a limit.

Question 7

AWS Lambda connecting to a VPC?

Answer 7

Enabling Lambda to access VPC resources

• Lambda needs the following:
  
  • Private subnet ID
  • Security group ID (with required access)
  • Lambda uses this information to set up ENIs using an avialable IP address from your private subnet.

Question 8

What are Step Functions?

Answer 8

• Provide a visual interface for serverless applications, which enables you to build, and run serverless applications as a series of steps.
• Each stpe in your application executes in order, as defined by your business logic.
• The output of one stpe may act as an input ti the next.

Question 9

What is AWS X-Ray?

Answer 9

• X-Ray is a tool which helps developers analyze and debug distributed applications.
• Allowing you to troubleshoot the root cause of performance issues and errors.
• Provides a visualization of your application’s underlyying components.
• The X-Ray service map provides an end-toend view of requests as they travel through your application.

Question 10

AWS X-Ray Integration?

Answer 10

• AWS Services
  
  • X-Ray can be used with:
    
    • EC2
    • Elastic Container Service
    • Lambda
    • Elastic Beanstalk
    • SNS
    • SQS
    • DynamoDB
    • Elastic Load Balancer
    • API Gateway
• Integrate with your Apps
  
  • ​X-Ray can be used with applications written in Java,Node.js, .Net, Go, Ruby and Python
• API Calls
  
  • X-Ray SDK automatically captures metadata for API calls made to AWS Services using the AWS SDK

Question 11

AWS X-Ray High-Level configuration?

Answer 11

High-level requirements:

• X-Ray SDK
• X-Ray daemon
• if you want to also record application specific information in the form of key-value pairs, use annotations to add user defined key-value to your X-Ray data

Question 12

AWS API Gateway importing APIs?

Answer 12

• Importing API definition files
  
  • You can use the API Gateway import API feature to import an API using a definition file
• Supported Protocols
  
  • OpenAPI, formerly known as Swagger, is supported
• Create New and Update Existing APIs
  
  • You can use an OpenAPI definition file to create a new API or update an existing API
• When dealing with legacy applications which use SOAP, you can configire API Gateway as a SOAP web service passthrough, or you can use API Gateway tp cpnvert the XML response to JSON.

https://rubix.nl/how-configure-amazon-api-gateway-soap-webservice-passthrough-minutes/

Question 13

AWS API Gateway Caching and Throtling?

Answer 13

• Caches your endpoints response
• TTL
  
  • When you enable cahcing, API Gateway caches responses from your endpoint for a specified time-to-live (TTL) period, in seconds. The default is 300 Seconds.
• API Gateway Returns the Cached Response
• Default Throttling Limits
  
  • API Gateway limits the steady-state request rate to 10,000 requests per second, per Region.
• Concurrent Requests Limits
  
  • maximum concurrent requests is 5,000 across all APIs per Region.
• 429 Error
  
  • If you exceed 10,00 requests per second. or 5,000 concurrent requests, you will receieve a 429 Too Many Requests error message