AWS Cloud Practitioner: Elastic Compute Cloud

In this short series, I outline the notes that I took while preparing for the AWS Cloud Practitioner exam.

These are my personal notes that I have made while working through the A Cloud Guru exam practitioner course. They are in no way official notes from AWS.

I would advise you that if you do use my notes to help you revise for this exam, that you use them as a supplement to the most recent information in the White Papers, Exam Guide and go over your knowledge with practice exam papers.

Previous notes within this blog series:

EC2 101

Elastic Compute Cloud (EC2) is virtual machines in the cloud
Reduces the time required to obtain and boot new server instances to minutes rather than months
Allows you to scale your capacity up and down and out (e.g. behind a load balancer)
Allows you to pay for only the capacity that you use as you use it by the hour or even by the second

Different Pricing Options

On Demand – pay a fixed rate by the hour or second with no commitment (linux by sec, windows by hour)
Reserved Instances – provide you with a capacity reservation and offers you a significant discount on the hourly charge for an instance.
Spot Instances – enables you to bid whatever price you want for the instance capacity, providing for even greater savings if you have flexible start and end times
Dedicated Hosts – Physical EC2 server dedicated for your use. Can help reduce costs by allowing you to use your existing server-bound software licenses

On Demand

For users that want low cost, flexible payment with no long term commitment or upfront payment.
Applications with short term, spiky or unpredictable workloads that cannot be interrupted
Applications being developed or tested on EC2 for the first time

Reserved Instances

Applications with steady state or predictable usage
Applications that require reserved capacity
Users can make upfront payments to reduce their total computing costs

Spot Instances

Applications that have flexible start and end times
Applications that are only feasible at very low compute prices
Users with an urgent need of large amount of computing capacity
If Amazon terminate your instance you will charged for partial usage, if you terminate the instance, you will be charged for the full hour

Dedicated Hosts

Physical EC2 servers
Useful for regulatory requirements that may not support multi-tenant virtualisation.
Great for licensing (which does not support multi-tenancy or cloud deployments)
Can be purchased On-Demand
Can be purchased as Reservation for up to 70% off the On-Demand price

EC2 Instance Types

Remember the letters not the numbers.

F FPGA
I IOPS
G Graphics
H High Disk Throughput
T cheap general purpose (T2 Micro)
D Density
R RAM
M main choice for general purpose apps
C Compute
P Graphics (think Pics)
X Extreme Memory
Z Extreme Memory AND CPU

What is EBS?

Elastic block storage
Allows you to create storage volumes and attach them to Amazon EC2 instances.
Once attached, you can create a file system on top of these volumes, run a database or use them like any block device.
EBS volumes are in AZ where they are automatically replicated to protect you from the failure of a single component
Like a D: drives on PCs

EBS Volume Types

SSD

General Purpose SSD (GP2)
- Balances both price and performance
- Ratio of 3 IOPS per GB with up to 10,000 IOPS and burst of up to 3000 IOPS
Provisioned IOPS SSD (IO1)
- Designed for I/O intensive applications such as large relational or NoSQL dbs
- More than 10000 IOPS
- Provision up to 20,000 IOPS per volume

HDD

Throughput Optimized HDD (ST1)
- Big data
- Data warehouses
- Log processing
- Cannot be a boot volume
Cold HDD (SC1)
- Lowest cost storage for infrequently accessed workloads
- File server
- Cannot be a boot volume
Magnetic (Standard)
- Lowest cost per GB of all EBS volume types that is bootable
- Ideal for workloads where data is accessed infrequently, and applications where the lowest storage cost is important
- Legacy, but can still be used

Using EC2

EC2 is a compute based service.
It is not serverless. It’s a virtual server.
Use a private key (.pem) to connect to EC2 (Mac) or Putty converting your .pem to a .ppk file.
Security groups are virtual firewalls in the cloud
You need to open ports to use them e.g. SSH (22) (only for Linux instances), HTTP (80), HTTPS (443), RDP (3389) (only for Windows)
Always design for failure. Have one EC2 instance in each AZ

Using the AWS Command Line

Mac

- ssh into the EC2 instance using command line.
- After downloading your private key
- Go to the location you downloaded your private key

chmod 400 <.pem name>.pem ssh ec2-user@ -i <.pem name>.pem

NOTE: Copy the IP address with dots not hyphens! The hyphens will not work.
Press yes if it prompts you about authenticity
Set yourself to be a super user using:
sudo su
yum update -y aws s3 ls *

*you may need to first aws configure

Add your access key ID from the S3 bucket and the secret key
Then set your default region e.g. eu-west-1 (Ireland)
Press Enter for the default output format
aws s3 ls

Windows

Download Putty
Using the private key that you downloaded from your AWS instance, open your .pem file in PuttyGen
Generate a .ppk key from your .pem file
Save without a password
Close PuttyGen
Open Putty
Go to Auth and navigate to your.ppk location
Go to AWS grab the public IP of your AWS EC2 instance
Go to the Session tab in Putty
Paste in your IP into the Saved Sessions box and press Save
Paste the IP into the Host Name field and press Open
When the terminal opens, login as ec2-user and press Enter

You can interact with AWS in 3 ways:
- Using the console (web interface)
- Using the Command Line Interface (CLI)
- Using the Software Development Kit (SDKs)
Linux server admin via Port 22
Microsoft server admin via Remote Desktop Port (RDP) Port 3389
Web server admin via Port 80 (HTTP) or 443 (HTTPS)
Security groups are like virtual firewalls in the cloud. When you want to let everything in 0.0.0.0/0. Just let in one IP in Public X.X.X.X/32. You need to open ports in order to use them.
Always Design for failure. Have one EC2 instance in each availability zone behind an Elastic Load Balancer.

Building a Web Server

Login to your ec2 instance by using ec2-user
Elevate the privileges of the user by using sudo su
Perform an update using yum update -y
Install apache to create a web server yum install httpd
Start the web server using service httpd start
Change directory to the content of the web server cd /var/www/html
Create an index.html using nano index.html
Add basic content to the page
Exit and save
In the browser, hit the public IP to see your webpage

Note: If you’re having issues connecting to your index.html content via your IP, check that the security groups on the web server are set up correctly. You need a security group for HTTP access to allow traffic into the server too, as well as SSH.