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Create Stack Hands-On

We are logging into the AWS Console and anchoring ourselves specifically in the Sydney (ap-southeast-2) region because Amazon Machine Image (AMI) IDs are strictly region-locked. We review how complex templates translate into drag-and-drop structural diagrams inside Infrastructure Composer (formerly Application Composer). Then, we upload a minimal YAML template named 0-just-ec2.yaml. AWS stages this file in Amazon S3, parses the declarative block, and provisions an isolated t3.micro EC2 instance in Availability Zone ap-southeast-2 without us clicking a single button inside the EC2 wizard.

Hands On​

Infrastructure Blueprint: Phase-by-Phase Setup​

Phase 1: Regional Alignment & Visualization Review​

  • The Regional Boundary Guard: Switch your console destination directly to ap-southeast-2. Running a CloudFormation template with a hardcoded ImageId in the wrong region causes the stack engine to crash immediately with an invalid AMI identifier error.
  • Canvas Examination: Explore a sample WordPress block template inside Infrastructure Composer. Note how complex, multi-tier YAML configurations parse into clean interactive nodes (like WebServerSecurityGroup or LaunchConfig) on a visual canvas, showing how infrastructure blocks map to each other.

Phase 2: Minimal EC2 Template Deployment​

  • Code Structural Inventory: Open up the basic target file 0-just-ec2.yaml in your workspace. The blueprint contains the exact bare minimum structural parameters required to instantiate an AWS compute node:
0-just-ec2.yaml
---
Resources:
  MyInstance: # The Logical ID of the resource
    Type: AWS::EC2::Instance # The resource type
    Properties:
      AvailabilityZone: ap-southeast-2a
      ImageId: ami-0c78ef10ebf8c08db # Amazon Linux 2023 AMI 2023.12.20260611.0 x86_64 HVM kernel-6.1 ap-southeast-2
      InstanceType: t3.micro

Phase 3: Launching the Stack Pipeline​

  • Wizard Execution: Inside the CloudFormation dashboard, click Create Stack (with new resources).
  • The S3 Staging Event: Choose Upload a template file and point it to your local 0-just-ec2.yaml. The moment you select it, the AWS Console quietly uploads that raw text file into an automated tracking bucket inside Amazon S3.
  • Naming and Submission: Title your stack EC2InstanceDemo, click through the default permission screens, and hit Submit.

Phase 4: Lifecycle Monitoring & Tag Verification​

  • Tracking State Transitions: Refresh the Events tab immediately. You will watch the deployment machine execute the provisioning pipeline:
    1. EC2InstanceDemo - CREATE_IN_PROGRESS
    2. MyInstance - CREATE_IN_PROGRESS
    3. MyInstance - CREATE_COMPLETE
    4. EC2InstanceDemo - CREATE_COMPLETE
  • Resource Introspection: Head over to the Resources tab, find the generated Physical ID (the instance ID string like i-0xxxxxx), and click it. This jumps you straight into the live Amazon EC2 Dashboard.
  • Metadata Tag Verification: Look at the Tags tab on the newly created instance. CloudFormation automatically injects three system auditing tags onto every resource it spins up:

Exam Tips​

  • AMI Region Locking Trap: This is a huge trap on the developer exam. AMIs are strictly region-specific. An AMI ID that represents Amazon Linux 2023 in us-east-1 does not exist or points to a completely different image in ap-southeast-2 (Sydney). If a question states that an uploaded template works perfectly in one region but crashes with an object isolation error when deployed in another, the hardcoded ImageId value is the root cause.
  • Tracking Resource Origin via Tags: If an auditing scenario asks how to quickly identify which specific CloudFormation stack created an untagged, orphaned volume or EC2 instance inside a crowded corporate account, look for answers that check the standard prefix tags: aws:cloudformation:stack-name and aws:cloudformation:logical-id. CloudFormation appends these by default without you writing them.

Practice Test​

Question: A development team copies a valid AWS CloudFormation template that successfully deploys an auto-scaled development environment in the us-east-1 region. However, when they attempt to deploy the exact same template file inside the eu-west-1 region to spin up a European staging cluster, the stack creation immediately fails and returns the error status: CloudFormation received a 400 response. Value (ami-0c7217cdde317cfec) for imageId is invalid. How should the developer fix this?

  • A. Grant the CloudFormation execution service role explicit IAM permissions to perform s3:GetObject against global bucket targets.
  • B. Modify the template to use a t2.micro instance type instead of regional compute boundaries.
  • C. Replace the hardcoded ImageId value with the corresponding valid AMI identifier unique to the eu-west-1 region, or abstract it using a CloudFormation Mappings block.
  • D. Re-run the stack creation process using JSON format instead of YAML to bypass string validation checks.

Correct Answer: C. Because AMI IDs are strictly bound to their respective geographic AWS regions, copying a template with a hardcoded image ID across regional lines will cause the stack generation engine to fail. The value must be updated to match the target region's local image catalog.