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Serverless

- Serverless is a new paradigm in which the developers don't have to manage servers anymore

- just deploy code, just deploy functions

- Serverless == FaaS(Function as a Service)

- Serverless was pioneered by AWS Lambda but now also includes anything that's managed such as databases, messaging, storage, etc.

- Serverless doesn't mean there are no servers

Serverless in AWS 

: AWS Lambda, DynamoDB, AWS Cognito, AWS API Gateway, S3, Fargate...

[ Why use AWS Lambda (compare Amazon EC2 with AWS Lambda) ] 

Amazon EC2

- Virtual Servers in the Cloud

- Limited by RAM and CPU

- Continuously running

- Scaling means intervention to add /remove servers

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

  Free tier of 1,000,000 AWS Lambda requests and 400,000 GBs of compute time

- 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 (up to 10GB of RAM)

- Increasing RAM will also improve CPU and network

[ AWS Lambda language support ]

- js

- Python

- Java

- C#

- Go

- Ruby

- Custom Runtime API 

- Lambda Container Image

  The container image must implement the Lambda Runtime API

  ECS / Fargate is preferred for running arbitrary(임의적인 멋대로인) Docker images

[ AWS Lambda Integrations Main ones ]

- API Gateway

- Kinesis

- Dynamo DB

- S3

- CloudFront

- CloudWatch Events Event Bridges

- CloudWatch Logs

- SNS

- SQS

- Cognito

[ Example : Serverless Thumbnail creation ]

[ Example : Serverless CRON job ]

[ AWS Lambda Pricing ]

- https://aws.amazon.com/lambda/pricing/ 

- Pay per calls 

  first 1,000,000 requests are free

  $0.20 per 1 million requests 

- Pay per duration : 

  400,000 GB seconds of compute time per month if FREE

  == 400,000 sec if function is 1GB RAM

  == 3,200,000 seconds if function is 128MB RAM

- After that $1.00 for 600,000 GB-sec

- It is usually very cheap to run AWS Lambda so it's very popular

[ AWS Lambda Limits to Know - per region ]

Execution :

1) Memory allocation 128mb-10GB (64mb increments)

2) Maximum execution time : 900 sec (15min)

3) Environment variables (4 KB)

4) Disk capacity in the function container (in /tmp) : 512MB

5) Concurrency executions : 1000 (can be increased)

Deployment :

1) Lambda function deployment size (compressed .zip) : 50MB

2) Size of uncompressed deployment (code + dependencies) : 250MB

3) Can use the /tmp directory to load other files at startup

4) Size of environment variables : 4 KB