Notes on: AWS Essentials: 5) EC2

Just a place to put some notes on the “AWS Essentials” course from https://linuxacademy.com

5) Elastic Compute Cloud (EC2)

5.1) EC2 Basics

Amazon Elastic Compute Cloud (Amazon EC2):

- Provides scalable computing capacity in the Amazon Web Services (AWS) cloud.

- Eliminates your need to invest in hardware up front, so you can develop and deploy applications faster.

- Enables you to scale up or down to handle changes in requirements or spikes in popularity, reducing your need to forecast traffic.

Basic Computer   EC2

Components     v Components

---------------+-----------

O/S            : AMIs

CPU            : Instance Type

Hard Drive     : EBS

Network Card   : IP Addressing

Firewall       : Security Groups

RAM            : RAM

Image: Services > Compute > EC2

Link: AWS: Instance Purchasing Options

Link: Amazon EC2 Pricing

Note: Free Tier use is available for EC2.

EC2 Instance Purchasing Options (most common):

- On-Demand

- Reserved

- Spot

On-Demand (most expense):

- Choose any instance type you like and provision/terminate at any time

- Only charged when the instance is running (billed per hour)

Reserved (significant price discount):

- Purchase an instance for a set time period of 1 or 3 years

- Pay upfront, partial upfront, no upfront

- Charged regardless of how often you use it

Spot (substantial price discount):

- “Bid” on an instance type, and only pay for and use when the spot price is equal or below your “bid” price

- Allows Amazon to sell the use of unused instances for short amounts of time

- Prices fluctuate based on supply and demand (billed per hour)

- Instances automatically terminate when spot price > “bid” price

How are you charged for using EC2?

1) Purchasing Option

2) Instance Type (processing power):

- General purpose

- Compute optimized

- GPU optimized

- Memory optimized

- Storage optimized

- EBS optimized (option for higher IOPS performance)

3) AMI Type (varies on O/S):

- Linux

- Windows

4) Data Transfer (in/out of the instance)

5) Region

5.2) Amazon Machine Images (AMIs)

Amazon Machine Image (AMI) provides the information (template) required to launch an instance (virtual server.)

AMIs come in 3 main categories:

1) Community AMIs: Free to use, essentially just an OS

2) AWS Marketplace AMIs: Pay to use, generally package with additional licensed software

3) My AMIs

Image: Amazon EC2 > Launch Instance

Image: AMI categories

5.3) Instance Types

When you launch and instance...

The instance type determines the (virtual) hardware used for your instance.

Instance Type Components:

(1) Family (General Purpose, Compute Optimized, Memory Optimized, Storage Optimized)

(2) Type

(3) vCPUs

(4) Memory (GiB)

(5) Instance Storage (GB)

(6) EBS-Optimized Available

(7) Network Performance

5.4) Elastic Block Store (EBS)

Amazon Elastic Block Store (EBS) provides block level storage volumes for use with EC2 instances.

- EBS volumes are highly available and reliable storage volumes that can be attached to any running instance that is in the same Availability Zone.

- EBS volumes that are attached to an EC2 instance are exposed as storage volumes that persist independently from the life of the instance.

AWS Definition of IOPs:

“IOPs are a unit measure representing input/output operations per second. The operations are measured in KiB, and the underlying drive technology determines the maximum amount of data that a volume type counts as a single I/O. I/O size is capped at 256 KiB for SSD volumes and 1024 KiB for HDD volumes.”

EBS volume size determines the amount of IOPS. Larger size = more IOPS.

“Root” vs Additional EBS Volumes

(1) Every EC2 instance MUST have a “root” volume, which may or may not be EBS

(2) By default, EBS “root” volumes are set to be deleted when the instance is terminated (you can choose to have EBS volume persist)

(3) During the creation of an EC2 instance (and afterwards) you can add additional EBS Volumes to the instance.

(4) Any Additional EBS volume can be attached or detached from the instance at any time, and is not deleted (by default) when the instance is terminated.

Snapshots:

- A snapshot is an “image” of an EBS volume that can be stored as a backup of the volume OR used to create a duplicate. It is NOT an active EBS volume (cannot attach or detach to an EC2 instance.)

- To restore create a new EBS volume using the snapshot as template.

Image: AWS Console > Services > EC2 > Elastic Block Store: (EBS) Volume and Snapshots

5.5) Security Groups

A security group acts as a virtual firewall that controls the traffic for one or more instances.

- You associate one or more security groups with an instance.

- Can modify the rules for a security group at any time.

- We evaluate all the rules from all the security groups that are associated with the instance.

Inbound and Outbound Rules

- When you create a new Security Group, ALL inbound traffic is DENIED and ALL outbound traffic is ALLOWED by default.

- All traffic is DENIED unless there is an EXPLICIT ALLOW rule for it (there are only ALLOW rules.)

Best Practice: Allow ONLY traffic that is required.

Image: AWS Console > Services > EC2 > Network & Security > Security Groups

Note: In the image above, inbound just allows traffic from whatever is in the security group.

5.6) IP Addressing

- (By default) ALL EC2 instances have a private IP address. Private IP addresses allow for instances to communicate with each other as long as they are located in the same VPC or broader private network.

- EC2 instances can be launched with or without a public IP address, depending on VPC/subnet settings. Public IP addresses are REQUIRED for the instance to communicate with the Internet.

Note: The “default” VPC and subnets are configured so that any new instance that is provisioned has a public IP address.

5.7) Provisioning EC2 (example)

AWS Console > Services > EC2 > Launch Instance

Step 1) Quick Start: Amazon Linux (Free tier eligible) > Select

Step 2) Instance Type: General Purpose t2.micro (Free tier eligible) > Next: Configure Instance Details

Step 3) Configure Instance Details: Configure > Next: Add Storage

Image: Step 3) Configure Instance Details (example)

Step 4) Add Storage: Configure > Next: Add Tags

Image: Step 4) Add Storage (example)

Step 5) Add Tag: Give the ‘Name’ key a value (optional) > Next: Configure Security Group

Step 6) Configure Security Group: Configure > Review and Launch

Image: Step 6) Configure Security Group (example)

Step 7) Review Instance Launch: Launch > Create a new key pair > Download Key Pair > Launch Instance

Image: Step 7) Downloading Key Pair prior to Launch Instance(s)

Give it a few minutes and your instance is up and running!

AWS Docs: Connect to Your Linux Instance

AWS Docs: Connecting to Your Linux Instance from Windows Using PuTTY

Image: AWS Console > Services > EC2 > Instances: Instances

Note: If you’re using the Free Tier, remember to stop your instances when you’re not using them.

5.8) Quiz: EC2 Essentials

T: When launching an EC2 instance, you need to select the AMI, Storage and Instance Type.

Q: What best describes IOPS?

A: Read/write performance of storage volumes & Input/output operations per second

Q: If you were to remove the route to the IGW from a route table, what would happen to traffic inside the VPC?

A: Traffic could be sent between EC2 instances inside the VPC but would not reach the Internet.

T: AMI = A preconfigured package that provides the information required to launch an EC2 instance.

T: Every EC2 instance is automatically assigned a private IP address. Public IP addresses are optional, but are required for direct Internet access.

T: EC2 stands for Elastic Compute Cloud

T: You can only configure ALLOW rules for security groups. If there is not an explicit allow rule for a certain type of traffic, then that traffic will be denied.

T: EBS volumes are the instance’s storage.