Launching an EC2 instance in AWS - Step-by-Step Execution

Process Flow - Launching an EC2 instance

Start: Define instance parameters

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Call AWS EC2 Launch API

↓

AWS validates parameters

↓

AWS provisions virtual server

↓

Instance state changes: pending -> running

↓

Instance ready with public IP

↓

User connects to instance

This flow shows the steps from setting up parameters to having a running EC2 instance ready for use.

Execution Sample

AWS

aws ec2 run-instances --image-id ami-12345678 --count 1 --instance-type t2.micro --key-name MyKeyPair --security-groups MySecurityGroup

This command launches one EC2 instance with specified image, type, key pair, and security group.

Process Table

Step	Action	Input/Parameters	AWS Response	Instance State
1	Define parameters	AMI=ami-12345678, Count=1, Type=t2.micro, Key=MyKeyPair, SG=MySecurityGroup	Parameters ready	N/A
2	Send launch request	RunInstances API call with parameters	Request accepted	pending
3	AWS validates parameters	Check AMI, instance type, key, SG	Validation successful	pending
4	Provision instance	Allocate resources	Instance created	pending
5	Instance state changes	AWS updates state	State changed to running	running
6	Assign public IP	AWS assigns IP	Public IP assigned	running
7	Instance ready	User can connect	Instance accessible	running
8	User connects	SSH or RDP connection	Connection established	running

💡 Instance is running and ready for user connection

Status Tracker

Variable	Start	After Step 2	After Step 5	After Step 7
Instance State	N/A	pending	running	running
Public IP	None	None	None	Assigned
AWS Response	None	Request accepted	State changed to running	Instance accessible

Key Moments - 3 Insights

Why does the instance state show 'pending' before 'running'?

Because AWS first prepares the instance resources (pending) before it is fully ready to use (running), as shown in execution_table rows 2 to 5.

What happens if the AMI ID is invalid?

AWS validation would fail at step 3, and the instance would not be created. The launch request would be rejected.

When can the user connect to the instance?

Only after the instance state is 'running' and a public IP is assigned, as shown in execution_table rows 6 and 7.

Visual Quiz - 3 Questions

Look at the execution table, what is the instance state right after the launch request is sent?

A pending

B running

C stopped

D terminated

💡 Hint

Check execution_table row 2 under 'Instance State'

At which step does AWS assign a public IP to the instance?

A Step 4

B Step 5

C Step 6

D Step 7

💡 Hint

Look at execution_table row 6 under 'Action' and 'AWS Response'

If the security group is missing, what would change in the execution table?

A Public IP would be assigned earlier

B Validation would fail at step 3

C Instance state would skip 'pending'

D User could connect immediately

💡 Hint

Refer to key_moments about validation failure and execution_table step 3

Concept Snapshot

Launch EC2 instance with AWS CLI:
aws ec2 run-instances --image-id <AMI> --count 1 --instance-type <type> --key-name <key> --security-groups <sg>
Instance state moves: pending -> running
Public IP assigned when running
User connects via SSH/RDP after running

Full Transcript

Launching an EC2 instance involves defining parameters like AMI, instance type, key pair, and security group. The AWS CLI command sends a launch request. AWS validates the parameters, provisions the instance, and changes its state from pending to running. Once running, AWS assigns a public IP. The user can then connect to the instance. The execution table traces each step and state change. Key moments include understanding the pending state, validation checks, and when the instance is ready for connection.

Practice

1. What does launching an EC2 instance in AWS create?

easy

A. A storage bucket

B. A virtual server in the cloud

C. A database instance

D. A physical server in your office

Solution

1. Step 1: Understand EC2 purpose

   EC2 stands for Elastic Compute Cloud, which provides virtual servers.

2. Step 2: Identify what launching means

   Launching an EC2 instance means creating a virtual server in AWS cloud.

3. Final Answer:

   A virtual server in the cloud -> Option B

4. Quick Check:

   EC2 instance = virtual server [OK]

Hint: EC2 = virtual server, not physical hardware [OK]

Common Mistakes:

• Confusing EC2 with physical hardware
• Thinking EC2 creates storage or database
• Mixing EC2 with S3 storage

2. Which AWS CLI command is used to launch a new EC2 instance?

easy

A. aws ec2 run-instances

B. aws ec2 start-instance

C. aws ec2 create-instance

D. aws ec2 deploy-instance

Solution

1. Step 1: Recall AWS CLI commands for EC2

   The correct command to launch EC2 instances is 'run-instances'.

2. Step 2: Eliminate incorrect commands

   Commands like 'create-instance', 'start-instance', and 'deploy-instance' do not exist or are incorrect.

3. Final Answer:

   aws ec2 run-instances -> Option A

4. Quick Check:

   Launch EC2 = run-instances command [OK]

Hint: Remember 'run-instances' to start EC2 instances [OK]

Common Mistakes:

• Using 'create-instance' which is invalid
• Confusing 'start-instance' with launching
• Assuming 'deploy-instance' is a valid command

3. What will happen if you run this command?

aws ec2 run-instances --image-id ami-12345678 --count 1 --instance-type t2.micro --key-name MyKeyPair --security-groups MySecurityGroup

medium

A. Deletes the specified AMI image

B. Creates a new security group named MySecurityGroup

C. Launches one t2.micro EC2 instance with specified settings

D. Starts an existing stopped EC2 instance

Solution

1. Step 1: Analyze the command parameters

   The command uses 'run-instances' with image ID, count=1, instance type, key pair, and security group.

2. Step 2: Understand the command effect

   This command launches one new EC2 instance of type t2.micro with the given AMI and security settings.

3. Final Answer:

   Launches one t2.micro EC2 instance with specified settings -> Option C

4. Quick Check:

   run-instances with parameters = launch instance [OK]

Hint: run-instances with --count 1 launches one instance [OK]

Common Mistakes:

• Thinking it deletes or modifies AMI
• Confusing security group creation with usage
• Assuming it starts an existing instance

4. You run this command but get an error: InvalidKeyPair.NotFound. What is the likely cause?

aws ec2 run-instances --image-id ami-87654321 --count 1 --instance-type t3.small --key-name WrongKey --security-groups Default

medium

A. The key pair named 'WrongKey' does not exist in your AWS account

B. The AMI ID is invalid

C. The instance type t3.small is not supported

D. The security group 'Default' is missing

Solution

1. Step 1: Understand the error message

   'InvalidKeyPair.NotFound' means the specified key pair is not found in your AWS account.

2. Step 2: Match error to command parameters

   The key-name 'WrongKey' likely does not exist or is misspelled, causing the error.

3. Final Answer:

   The key pair named 'WrongKey' does not exist in your AWS account -> Option A

4. Quick Check:

   InvalidKeyPair error = missing key pair [OK]

Hint: Check key pair name spelling if InvalidKeyPair error occurs [OK]

Common Mistakes:

• Assuming AMI or instance type caused the error
• Thinking security group 'Default' is missing
• Ignoring key pair existence in the region

5. You want to launch 3 EC2 instances with the same settings but different subnet IDs for high availability. Which approach is best?

hard

A. Use aws ec2 create-subnet to create three subnets and launch one instance

B. Run one aws ec2 run-instances command with --count 3 and a single --subnet-id

C. Launch one instance and then clone it twice manually

D. Run three separate aws ec2 run-instances commands, each with a different --subnet-id

Solution

1. Step 1: Understand subnet and instance launch

   Each EC2 instance can be launched in only one subnet at a time.

2. Step 2: Plan for multiple subnets

   To launch instances in different subnets, run separate commands specifying each subnet ID.

3. Step 3: Evaluate options

   Run three separate aws ec2 run-instances commands, each with a different --subnet-id. This runs three commands with different subnet IDs, ensuring instances spread across subnets.

4. Final Answer:

   Run three separate aws ec2 run-instances commands, each with a different --subnet-id -> Option D

5. Quick Check:

   One subnet per instance, multiple commands for multiple subnets [OK]

Hint: One subnet per instance, use multiple commands for multiple subnets [OK]

Common Mistakes:

• Trying to launch multiple subnets in one command
• Assuming cloning instances copies subnet settings
• Confusing subnet creation with instance launch