EC2 (Elastic Compute Cloud)

💡 Definition

Amazon EC2 is a web service that provides secure, resizable compute capacity in the cloud. It allows you to launch virtual servers (instances) to run applications.

🔑 Key Concepts

• Instance Types: Different hardware configurations optimized for different tasks (e.g., Compute Optimized, Memory Optimized).
• AMI (Amazon Machine Image): The template used to create the instance (contains OS + apps).
• EBS (Elastic Block Store): The persistent network storage drive attached to the instance.
• Security Group: The virtual firewall that controls traffic to/from the instance.
• User Data: Script run once upon instance launch (for bootstrapping).

⚙️ How it Works

1. Select Region: Choose where to run the server.
2. Select AMI: Choose the OS (Linux, Windows).
3. Choose Instance Type: Select CPU/RAM capacity (e.g., t2.micro).
4. Configure Network: Place in a VPC and Subnet.
5. Attach Storage: Add EBS volumes.
6. Launch: Connect via SSH (Linux) or RDP (Windows).

🎯 Use Cases

• Hosting websites and web applications.
• Running backend servers and APIs.
• High-performance computing (HPC) and batch processing.
• Gaming servers.

💰 Pricing Model

• On-Demand: Pay by the second/hour (no commitment).
• Reserved Instances: 1-3 year commitment for discount (up to 72%).
• Savings Plans: Commit to usage ($/hr) for discount.
• Spot Instances: Bid on spare capacity (up to 90% off, can be interrupted).

📝 Exam Tips (CLF-C02)

• Remember that EC2 is IaaS (Infrastructure as a Service).
• You are responsible for OS patching (Shared Responsibility Model).
• Vertical Scaling: Changing instance type (e.g., t2.micro to t2.large).
• Horizontal Scaling: Adding more instances (using Auto Scaling Group).

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See Also: * Auto Scaling * Load Balancer