EC2

Question 1

What is Amazon EC2 ?

Answer 1

Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides secure, resizable compute capacity in the cloud. It’s designed to simplify the process of obtaining and configuring scalable compute resources for all users.

• EC2 is one of the most popular of AWS’ offering
• EC2 = Elastic Compute Cloud = Infrastructure as a Service
• It mainly consists in the capability of :
  
  • Renting virtual machines (EC2)
  • Storing data on virtual drives (EBS)
  • Distributing load across machines (ELB)
  • Scaling the services using an auto-scaling group (ASG)
• Knowing EC2 is fundamental to understand how the Cloud works

Question 2

What are the EC2 sizing & configuration options ?

Answer 2

• Operating System (OS): Linux, Windows or Mac OS
• How much compute power & cores (CPU)
• How much random-access memory (RAM)
• How much storage space:
  
  • Network-attached (EBS & EFS)
  • hardware (EC2 Instance Store)
• Network card: speed of the card, Public IP address
• Firewall rules: security group
• Bootstrap script (configure at first launch): EC2 User Data

Question 3

Talk about EC2 User Data ?

Answer 3

• It is possible to bootstrap our instances using an EC2 User data script.
• bootstrapping means launching commands when a machine starts
• That script is only run once at the instance first start
• EC2 user data is used to automate boot tasks such as:
  
  • Installing updates
  • Installing software
  • Downloading common files from the internet
  • Anything you can think of
• The EC2 User Data Script runs with the root user

Question 4

What is an EC2 instance type and what can be said about EC2 Instance Types - Overview ?

Answer 4

In Amazon EC2, an instance type essentially determines the hardware of the host computer used for the instance. Each instance type offers different compute, memory, and storage capabilities and is optimized to suit different types of applications.

You can use different types of EC2 instances that are optimised for
different use cases (https://aws.amazon.com/ec2/instance-types/)
* AWS has the following naming convention:

m5.2xlarge

• m: instance class
• 5: generation (AWS improves them over time)
• 2xlarge: size within the instance class

Question 5

Which are the EC2 Instance Types ?

Answer 5

• General Purpose
• Compute Optimized
• Memory Optimized
• Storage Optimized

Question 6

What is the General Purpose EC2 instance type good for?

Answer 6

• Great for a diversity of workloads such as web servers or code repositories
• Balance between:
• Compute
• Memory
• Networking
• We will be using the t2.micro which is a General Purpose EC2
  instance

Question 7

What is the Compute Optimized EC2 instance type good for?

Answer 7

• Great for compute-intensive tasks that require high performance
  processors:
  
  • Batch processing workloads
  • Media transcoding
  • High performance web servers
  • High performance computing (HPC)
  • Scientific modeling & machine learning
  • Dedicated gaming servers

Question 8

What is the Memory Optimized EC2 instance type good for?

Answer 8

• Fast performance for workloads that process large data sets in memory
• Use cases:
  
  • High performance, relational/non-relational databases
  • Distributed web scale cache stores
  • In-memory databases optimized for BI (business intelligence)
  • Applications performing real-time processing of big unstructured data

Question 9

What is the Storage Optimized EC2 instance type good for?

Answer 9

• Great for storage-intensive tasks that require high, sequential read and write
  access to large data sets on local storage
• Use cases:
  
  • High frequency online transaction processing (OLTP) systems
  • Relational & NoSQL databases
  • Cache for in-memory databases (for example, Redis)
  • Data warehousing applications
  • Distributed file systems

Question 10

What are Security Groups ?

Answer 10

• Security Groups are the fundamental of network security in AWS
• They control how traffic is allowed into or out of our EC2 Instances.
• Security groups only contain allow rules
• Security groups rules can reference by IP or by security group

Question 11

What else is there regarding Security Groups ?

Answer 11

• Security groups are acting as a “firewall” on EC2 instances
• They regulate:
  
  • Access to Ports
  • Authorised IP ranges – IPv4 and IPv6
  • Control of inbound network (from other to the instance)
  • Control of outbound network (from the instance to other)

Question 12

What is a Security Groups
Diagram ?

Answer 12

A security group diagram would show how security groups control inbound and outbound traffic for AWS EC2 instances.

Question 13

What are some good to know information about Security Groups?

Answer 13

• Can be attached to multiple instances
• Locked down to a region / VPC combination
• Does live “outside” the EC2 – if traffic is blocked the EC2 instance won’t see it
• It’s good to maintain one separate security group for SSH access
• If your application is not accessible (time out), then it’s a security group issue
• If your application gives a “connection refused“ error, then it’s an application
  error or it’s not launched
• All inbound traffic is blocked by default
• All outbound traffic is authorised by default

Question 14

What are References to Other Security Groups ?

Answer 14

To depict referencing other security groups, you could have lines connecting one security group to another, with labels indicating whether this connection represents inbound or outbound traffic. The connected security groups indicate that the rules in one security group are referencing the rules in the other security group.

Question 15

What are some Classic Ports that is recomended to know ?

Answer 15

• 22 = SSH (Secure Shell) - log into a Linux instance
• 21 = FTP (File Transfer Protocol) – upload files into a file share
• 22 = SFTP (Secure File Transfer Protocol) – upload files using SSH
• 80 = HTTP – access unsecured websites
• 443 = HTTPS – access secured websites
• 3389 = RDP (Remote Desktop Protocol) – log into a Windows instance

Question 16

Whick are the EC2 Instances Purchasing Options ?

Answer 16

• On-Demand Instances – short workload, predictable pricing, pay by second
• Reserved (1 & 3 years)
  
  • Reserved Instances – long workloads
  • Convertible Reserved Instances – long workloads with flexible instances
• Savings Plans (1 & 3 years) –commitment to an amount of usage, long workload
• Spot Instances – short workloads, cheap, can lose instances (less reliable)
• Dedicated Hosts – book an entire physical server, control instance placement
• Dedicated Instances – no other customers will share your hardware
• Capacity Reservations – reserve capacity in a specific AZ for any duration

Question 17

What do you know about EC2 On Demand ?

Answer 17

• Pay for what you use:
  
  • Linux or Windows - billing per second, after the first minute
  • All other operating systems - billing per hour
• Has the highest cost but no upfront payment
• No long-term commitment
• Recommended for short-term and un-interrupted workloads, where
  you can’t predict how the application will behave

Question 18

What do you know about EC2 Reserved Instances ?

Answer 18

• Up to 72% discount compared to On-demand
• You reserve a specific instance attributes (Instance Type, Region, Tenancy, OS)
• Reservation Period – 1 year (+discount) or 3 years (+++discount)
• Payment Options – No Upfront (+), Partial Upfront (++), All Upfront (+++)
• Reserved Instance’s Scope – Regional or Zonal (reserve capacity in an AZ)
• Recommended for steady-state usage applications (think database)
• You can buy and sell in the Reserved Instance Marketplace
• Convertible Reserved Instance
  
  • Can change the EC2 instance type, instance family, OS, scope and tenancy
  • Up to 66% discount

Question 19

What do you know about EC2 Savings Plans ?

Answer 19

• Get a discount based on long-term usage (up to 72% - same as RIs)
• Commit to a certain type of usage ($10/hour for 1 or 3 years)
• Usage beyond EC2 Savings Plans is billed at the On-Demand price
• Locked to a specific instance family & AWS region (e.g., M5 in us-east-1)
• Flexible across:
  
  • Instance Size (e.g., m5.xlarge, m5.2xlarge)
  • OS (e.g., Linux, Windows)
  • Tenancy (Host, Dedicated, Default)

Question 20

What do you know about EC2 Spot Instances ?

Answer 20

• Can get a discount of up to 90% compared to On-demand
• Instances that you can “lose” at any point of time if your max price is less than the
  current spot price
• The MOST cost-efficient instances in AWS
• Useful for workloads that are resilient to failure
  
  • Batch jobs
  • Data analysis
  • Image processing
  • Any distributed workloads
  • Workloads with a flexible start and end time
• Not suitable for critical jobs or databases

Question 21

What do you know about EC2 Dedicated Hosts ?

Answer 21

• A physical server with EC2 instance capacity fully dedicated to your use
• Allows you address compliance requirements and use your existing server- bound software licenses (per-socket, per-core, pe—VM software licenses)
• Purchasing Options:
  
  • On-demand – pay per second for active Dedicated Host
  • Reserved - 1 or 3 years (No Upfront, Partial Upfront, All Upfront)
• The most expensive option
• Useful for software that have complicated licensing model (BYOL – Bring Your Own License)
• Or for companies that have strong regulatory or compliance needs

Question 22

What do you know about EC2 Dedicated Instances ?

Answer 22

• Instances run on hardware that’s
  dedicated to you
• May share hardware with other
  instances in same account
• No control over instance placement
  (can move hardware after Stop / Start)

Question 23

What do you know about EC2 Capacity Reservations ?

Answer 23

• Reserve On-Demand instances capacity in a specific AZ for any duration
• You always have access to EC2 capacity when you need it
• No time commitment (create/cancel anytime), no billing discounts
• Combine with Regional Reserved Instances and Savings Plans to benefit
  from billing discounts
• You’re charged at On-Demand rate whether you run instances or not
• Suitable for short-term, uninterrupted workloads that needs to be in a
  specific AZ

Question 24

Which purchasing option is right for me?

Answer 24

• On demand: coming and staying in resort whenever we like, we pay the full price
• Reserved: like planning ahead and if we plan to stay for a long time, we may get a good discount.
• Savings Plans: pay a certain amount per hour for certain period and stay in any room type (e.g.,
  King, Suite, Sea View, …)
• Spot instances: the hotel allows people to bid for the empty rooms and the highest bidder keeps the
  rooms. You can get kicked out at any time
• Dedicated Hosts: We book an entire building of the resort
• Capacity Reservations: you book a room for a period with full price even you don’t stay in it

Question 25

What is the shared Responsibility Model for EC2 ?

Answer 25