5. Compute Services ECS, Lambda, batch, Lightsail

What is Docker?

A software development platform to deploy apps, where apps are packaged in containers that can be run on any OS

What is the key benefit of packaging apps in Docker containers?

Apps run the same regardless of where they're run — any machine, no compatibility issues, predictable behaviour, less work, easier to maintain and deploy, works with any language, any OS, any technology

How quickly can Docker containers scale up and down?

Very quickly — in seconds

Where are Docker images stored?

In Docker repositories — public: Docker Hub (base images for technologies/OS like Ubuntu, MySQL, NodeJS, Java); private: Amazon ECR (Elastic Container Registry)

How does Docker compare to virtual machines?

Docker is "sort of" a virtualisation technology, but not exactly — resources are shared with the host, so you can run many containers on one server

What is ECS?

Elastic Container Service — launch Docker containers on AWS

Who manages the infrastructure with ECS?

You must provision & maintain the infrastructure (the EC2 instances); AWS takes care of starting/stopping containers

What load balancer does ECS integrate with?

The Application Load Balancer

What is AWS Fargate?

A serverless offering to launch Docker containers on AWS — you do not provision the infrastructure (no EC2 instances to manage), AWS just runs containers for you based on the CPU/RAM you need

What is ECR?

Elastic Container Registry — a private Docker registry on AWS where you store your Docker images so they can be run by ECS or Fargate

What is EKS?

Elastic Kubernetes Service — allows you to launch managed Kubernetes clusters on AWS

What is Kubernetes?

An open-source system for management, deployment and scaling of containerised apps (Docker)

Where can EKS containers be hosted?

On EC2 instances or Fargate (serverless)

Is Kubernetes cloud-agnostic?

Yes — it can be used in any cloud (Azure, GCP, etc.)

What is serverless?

A new paradigm in which developers don't have to manage servers anymore — they just deploy code / functions

What was initial serverless known as?

FaaS — Function as a Service

Who pioneered serverless, and what does it include now?

AWS Lambda pioneered it; now it includes anything that's managed: databases, messaging, storage etc

Does serverless mean there are no servers?

No — it means you don't manage / provision / see them

Which serverless services were used earlier in the course?

Amazon S3, DynamoDB, Fargate, and Lambda

How does Amazon EC2 compare to Lambda?

EC2: virtual servers in the cloud, limited by RAM and CPU, continuously running, scaling means intervention to add/remove servers

What is Amazon Lambda in contrast to EC2?

Virtual functions — no servers to manage, limited by time (short executions), run on-demand, scaling is automated

What is Lambda's pricing model?

Pay per request and compute time, with a free tier of 1,000,000 requests and 400,000 GB-seconds of compute time

What does "event-driven" mean for Lambda?

Functions get invoked by AWS when needed

How do you monitor Lambda?

Easily, through AWS CloudWatch

How much RAM can a Lambda function have, and what else does increasing RAM improve?

Up to 10GB of RAM — increasing RAM also improves CPU and network

Which languages does Lambda support?

Node.js (JavaScript), Python, Java, C# (.NET Core) / PowerShell, Ruby, and Custom Runtime API (community supported, e.g. Rust or Golang)

Can Lambda run container images?

Yes, but the container image must implement the Lambda Runtime API — ECS/Fargate is preferred for running arbitrary Docker images

What is Lambda's pay-per-call pricing?

First 1,000,000 requests are free, then $0.20 per 1 million requests thereafter ($0.0000002 per request)

What is Lambda's pay-per-duration pricing?

Billed in 1 ms increments; 400,000 GB-seconds of compute time per month free (= 400,000 seconds at 1GB RAM, or 3,200,000 seconds at 128MB RAM), then $1.00 for 600,000 GB-seconds

Why is Lambda so popular?

It is usually very cheap to run

What is Amazon API Gateway?

A fully managed service for developers to easily create, publish, maintain, monitor, and secure APIs — serverless and scalable; example use: building a serverless API

Which API types does API Gateway support?

RESTful APIs and WebSocket APIs

What features does API Gateway support?

Security, user authentication, API throttling, API keys, monitoring

What is AWS Batch?

Fully managed batch processing at any scale — efficiently run 100,000s of computing batch jobs on AWS

What is a "batch" job?

A job with a start and an end (as opposed to continuous)

What compute does AWS Batch launch?

It dynamically launches EC2 instances or Spot Instances, provisioning the right amount of compute/memory

How are AWS Batch jobs defined and run?

Defined as Docker images and run on ECS

What is AWS Batch helpful for?

Cost optimisations and focusing less on the infrastructure

What are Lambda's limitations compared to Batch?

Time limit, limited runtimes, limited temporary disk space — but serverless

What are Batch's characteristics compared to Lambda?

No time limit, any runtime as long as it's packaged as a Docker image, relies on EBS / instance store for disk space, and relies on EC2 (can be managed by AWS)

What does Amazon Lightsail provide?

Virtual servers, storage, databases, and networking with low & predictable pricing

What is Lightsail an alternative to?

A simpler alternative to using EC2, RDS, ELB, EBS, Route 53 — great for people with little cloud experience

What are use cases for Lightsail?

Simple web applications (templates for LAMP, Nginx, MEAN, Node.js), websites (templates for WordPress, Magento, Plesk, Joomla), and dev/test environments

What are Lightsail's limitations?

High availability but no auto-scaling and limited AWS integrations

Can you monitor Lightsail resources?

Yes — you can set up notifications and monitoring of your Lightsail resources

Summarise Lambda in one line

Serverless, Function as a Service, seamless scaling, reactive

How is Lambda billed?

By the time run multiplied by the RAM provisioned, and by the number of invocations

What is Lambda's maximum invocation time?

Up to 15 minutes

What are example Lambda use cases?

Creating thumbnails for images uploaded onto S3, and running a serverless cron job

How do you expose Lambda functions as an HTTP API?

With API Gateway