EC2: Virtual Servers in the Cloud

Amazon Elastic Compute Cloud (EC2) is one of the oldest and most fundamental AWS services. It provides resizable virtual servers in the cloud, giving you complete control over your computing resources. In this lesson, we'll explore how EC2 works and launch your first instance.

What You'll Learn

By the end of this lesson, you'll understand EC2 concepts, instance types, pricing models, and how to launch, connect to, and manage EC2 instances.

What is EC2?

EC2 lets you run virtual servers (called instances) in AWS data centers. Think of it as renting a computer in the cloud that you can configure however you want.

Why Use EC2?

• Flexibility - Choose the exact CPU, memory, and storage you need
• Scalability - Launch more instances in seconds when demand increases
• Control - Full root/admin access to your virtual servers
• Cost-effective - Pay only for what you use, by the second
• Global - Launch instances in any AWS region

Common Use Cases

• Web servers and application servers
• Development and testing environments
• Batch processing and data analysis
• Machine learning model training
• Game servers
• Database servers (though managed options like RDS are often better)

EC2 Instance Components

An EC2 instance consists of several components:

Amazon Machine Image (AMI)

An AMI is a template that contains the operating system and software for your instance. AWS provides:

• Amazon Linux 2/2023 - AWS's own Linux distribution
• Ubuntu - Popular Linux distribution
• Windows Server - Various versions
• Red Hat Enterprise Linux - Enterprise Linux
• macOS - For building Apple applications

You can also create custom AMIs from your configured instances.

Instance Type

The instance type determines the hardware specifications:

t3.micro
│  │
│  └─ Size (nano, micro, small, medium, large, xlarge, 2xlarge, etc.)
└─── Family (general purpose, compute, memory, storage, accelerated)

Common Instance Families

Family	Optimized For	Example Use Case
t3, t3a	General purpose, burstable	Web servers, small databases
m6i, m6a	General purpose, balanced	Application servers
c6i, c6a	Compute intensive	Batch processing, gaming
r6i, r6a	Memory intensive	In-memory databases, caching
p4, g5	GPU/Accelerated	Machine learning, graphics
i3, d2	Storage intensive	Data warehousing

Free Tier Instance

For learning, use t2.micro or t3.micro - these are Free Tier eligible (750 hours/month for 12 months).

Storage (EBS)

Amazon Elastic Block Store (EBS) provides persistent storage for EC2 instances. Think of it like a virtual hard drive.

EBS Volume Types:

Type	Description	Use Case
gp3, gp2	General Purpose SSD	Most workloads
io2, io1	Provisioned IOPS SSD	Databases requiring high IOPS
st1	Throughput Optimized HDD	Big data, data warehouses
sc1	Cold HDD	Infrequently accessed data

Security Groups

Security groups act as virtual firewalls controlling inbound and outbound traffic to your instances.

Key concepts:

• By default, all inbound traffic is blocked
• By default, all outbound traffic is allowed
• Rules are stateful - responses to allowed inbound traffic are automatically allowed out
• You specify rules by protocol, port, and source/destination

Example rules:

Type	Protocol	Port	Source	Purpose
SSH	TCP	22	My IP	Connect via SSH
HTTP	TCP	80	0.0.0.0/0	Web traffic (anyone)
HTTPS	TCP	443	0.0.0.0/0	Secure web traffic
RDP	TCP	3389	My IP	Windows remote desktop

Key Pairs

Key pairs provide secure SSH access to Linux instances (and encrypted password retrieval for Windows).

• Public key - Stored on the EC2 instance
• Private key - Downloaded by you, never shared

Keep your private key secure! Anyone with it can access your instances.

Launching Your First EC2 Instance

Let's launch a Linux instance step by step.

Step 1: Open EC2 Console

1. Go to the EC2 dashboard
2. Click "Launch instance"

Step 2: Name and Tags

1. Give your instance a name (e.g., "my-first-instance")
2. Add additional tags if needed (optional)

Step 3: Choose an AMI

1. Select "Amazon Linux 2023 AMI" (Free Tier eligible)
2. Verify it says "Free tier eligible"

Step 4: Choose Instance Type

1. Select "t2.micro" or "t3.micro" (Free Tier eligible)
2. Note the specs: 1 vCPU, 1 GB memory

Step 5: Key Pair

1. Click "Create new key pair"
2. Name it (e.g., "my-key-pair")
3. Choose key pair type: RSA
4. Choose format: .pem (Linux/Mac) or .ppk (Windows with PuTTY)
5. Click "Create key pair" - the file downloads automatically

Important: Store this file securely. You can't download it again.

Step 6: Network Settings

1. Keep the default VPC
2. Enable "Allow SSH traffic from My IP"
3. Optionally enable HTTP/HTTPS if running a web server

Step 7: Configure Storage

1. Default 8 GB gp3 is fine for learning
2. Can increase up to 30 GB in Free Tier

Step 8: Launch

1. Review your settings
2. Click "Launch instance"
3. Wait for the instance to start (Instance State: running)

Connecting to Your Instance

Connecting via SSH (Linux/Mac)

# Set correct permissions on key file
chmod 400 my-key-pair.pem

# Connect to instance
ssh -i my-key-pair.pem ec2-user@<public-ip-address>

Replace <public-ip-address> with your instance's public IP (found in the EC2 console).

Connecting via EC2 Instance Connect

AWS provides a browser-based SSH connection:

1. Select your instance in the EC2 console
2. Click "Connect"
3. Choose "EC2 Instance Connect"
4. Click "Connect"

A terminal opens in your browser - no key file needed!

Connecting via Session Manager

For instances without public IPs or SSH access:

1. Ensure the instance has an IAM role with AmazonSSMManagedInstanceCore policy
2. Select your instance
3. Click "Connect"
4. Choose "Session Manager"
5. Click "Connect"

Instance Lifecycle

EC2 instances have several states:

State	Description	Billing
pending	Instance is starting	No charge
running	Instance is active and accessible	Charges apply
stopping	Instance is shutting down	Charges may apply
stopped	Instance is off but can be restarted	No compute charge (EBS charges apply)
terminated	Instance is permanently deleted	No charge

Managing Instance State

From the EC2 console, select your instance and use the "Instance state" dropdown:

• Start - Boot a stopped instance
• Stop - Shut down but preserve the instance
• Reboot - Restart the instance
• Terminate - Permanently delete the instance

Warning: Termination is permanent. The instance and its root volume are deleted.

EC2 Pricing Models

AWS offers several pricing options for EC2:

On-Demand

Pay by the second (or hour) with no commitment.

• Best for: Development, testing, unpredictable workloads
• Pricing: Highest rate but most flexible
• Commitment: None

Spot Instances

Bid on unused EC2 capacity at up to 90% discount.

• Best for: Flexible, fault-tolerant workloads
• Pricing: Up to 90% off On-Demand
• Risk: Instances can be terminated with 2-minute notice

Reserved Instances

Commit to 1 or 3 years for significant discounts.

• Best for: Steady-state, predictable workloads
• Pricing: Up to 72% off On-Demand
• Commitment: 1 or 3 years

Savings Plans

Flexible pricing model with commitment to usage amount.

• Best for: Flexible commitments across instance types
• Pricing: Up to 72% off On-Demand
• Commitment: 1 or 3 years, $/hour

Elastic IP Addresses

By default, public IPs change when you stop/start an instance. Elastic IPs are static public IPs you can associate with instances.

Key points:

• Elastic IPs are free while associated with a running instance
• Charged if allocated but not used (to prevent hoarding)
• Can move between instances

Best Practices

1. Use the smallest instance that meets your needs - Resize later if needed
2. Stop instances you're not using - Avoid unnecessary charges
3. Use Security Groups wisely - Only open ports you need
4. Don't use default VPC for production - Create custom VPCs
5. Back up important data - Use EBS snapshots
6. Monitor costs - Use Cost Explorer and Budgets
7. Use IAM roles, not access keys - More secure for instances accessing AWS services

Key Takeaways

• EC2 provides virtual servers in the cloud with flexible configuration
• AMIs are templates containing the OS and software
• Instance types determine CPU, memory, and networking capabilities
• Security groups control inbound and outbound traffic
• Key pairs enable secure SSH access
• On-Demand pricing is flexible; Reserved and Savings Plans offer discounts
• Stop instances to save money while preserving them; terminate to delete permanently

What's Next

EC2 gives you full control over your compute resources, but sometimes you want even simpler compute without managing servers at all. In the next lesson, we'll explore AWS Lambda - serverless computing where you just upload your code and AWS handles everything else.