Cloudformation Best Practices V2

cloudformation-best-practices

Overview

This public intake copy packages plugins/antigravity-awesome-skills/skills/cloudformation-best-practices from https://github.com/sickn33/antigravity-awesome-skills into the native Omni Skills editorial shape without hiding its origin.

Use it when the operator needs the upstream workflow, support files, and repository context to stay intact while the public validator and private enhancer continue their normal downstream flow.

This intake keeps the copied upstream files intact and uses the external_source block in metadata.json plus ORIGIN.md as the provenance anchor for review.

You are an expert in AWS CloudFormation specializing in template optimization, stack architecture, and production-grade infrastructure deployment.

Imported source sections that did not map cleanly to the public headings are still preserved below or in the support files. Notable imported sections: Limitations.

When to Use This Skill

Use this section as the trigger filter. It should make the activation boundary explicit before the operator loads files, runs commands, or opens a pull request.

• Writing or reviewing CloudFormation templates (YAML/JSON)
• Optimizing existing templates for maintainability and cost
• Designing nested or cross-stack architectures
• Troubleshooting stack creation/update failures and drift
• The user prefers CDK or Terraform over raw CloudFormation
• The task is application code, not infrastructure

Operating Table

Workflow

This workflow is intentionally editorial and operational at the same time. It keeps the imported source useful to the operator while still satisfying the public intake standards that feed the downstream enhancer flow.

1. Use YAML over JSON for readability.
2. Parameterize environment-specific values; use Mappings for static lookups.
3. Apply DeletionPolicy: Retain on stateful resources (RDS, S3, DynamoDB).
4. Use Conditions to support multi-environment templates.
5. Validate templates with aws cloudformation validate-template before deployment.
6. Prefer !Sub over !Join for string interpolation.
7. Confirm the user goal, the scope of the imported workflow, and whether this skill is still the right router for the task.

Imported Workflow Notes

Imported: Instructions

1. Use YAML over JSON for readability.
2. Parameterize environment-specific values; use Mappings for static lookups.
3. Apply DeletionPolicy: Retain on stateful resources (RDS, S3, DynamoDB).
4. Use Conditions to support multi-environment templates.
5. Validate templates with aws cloudformation validate-template before deployment.
6. Prefer !Sub over !Join for string interpolation.

Imported: Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Examples

Example 1: Ask for the upstream workflow directly

Use @cloudformation-best-practices-v2 to handle <task>. Start from the copied upstream workflow, load only the files that change the outcome, and keep provenance visible in the answer.

Explanation: This is the safest starting point when the operator needs the imported workflow, but not the entire repository.

Example 2: Ask for a provenance-grounded review

Review @cloudformation-best-practices-v2 against metadata.json and ORIGIN.md, then explain which copied upstream files you would load first and why.

Explanation: Use this before review or troubleshooting when you need a precise, auditable explanation of origin and file selection.

Example 3: Narrow the copied support files before execution

Use @cloudformation-best-practices-v2 for <task>. Load only the copied references, examples, or scripts that change the outcome, and name the files explicitly before proceeding.

Explanation: This keeps the skill aligned with progressive disclosure instead of loading the whole copied package by default.

Example 4: Build a reviewer packet

Review @cloudformation-best-practices-v2 using the copied upstream files plus provenance, then summarize any gaps before merge.

Explanation: This is useful when the PR is waiting for human review and you want a repeatable audit packet.

Imported Usage Notes

Imported: Examples

Example 1: Parameterized VPC Template

AWSTemplateFormatVersion: "2010-09-09"
Description: Production VPC with public and private subnets

Parameters:
  Environment:
    Type: String
    AllowedValues: [dev, staging, prod]
  VpcCidr:
    Type: String
    Default: "10.0.0.0/16"

Conditions:
  IsProd: !Equals [!Ref Environment, prod]

Resources:
  VPC:
    Type: AWS::EC2::VPC
    Properties:
      CidrBlock: !Ref VpcCidr
      EnableDnsSupport: true
      EnableDnsHostnames: true
      Tags:
        - Key: Name
          Value: !Sub "${Environment}-vpc"

Outputs:
  VpcId:
    Value: !Ref VPC
    Export:
      Name: !Sub "${Environment}-VpcId"

Best Practices

Treat the generated public skill as a reviewable packaging layer around the upstream repository. The goal is to keep provenance explicit and load only the copied source material that materially improves execution.

• ✅ Do: Use Outputs with Export for cross-stack references
• ✅ Do: Add DeletionPolicy and UpdateReplacePolicy on stateful resources
• ✅ Do: Use cfn-lint and cfn-nag in CI pipelines
• ❌ Don't: Hardcode ARNs or account IDs — use !Sub with pseudo parameters
• ❌ Don't: Put all resources in a single monolithic template
• Keep the imported skill grounded in the upstream repository; do not invent steps that the source material cannot support.
• Prefer the smallest useful set of support files so the workflow stays auditable and fast to review.

Imported Operating Notes

Imported: Best Practices

• ✅ Do: Use Outputs with Export for cross-stack references
• ✅ Do: Add DeletionPolicy and UpdateReplacePolicy on stateful resources
• ✅ Do: Use cfn-lint and cfn-nag in CI pipelines
• ❌ Don't: Hardcode ARNs or account IDs — use !Sub with pseudo parameters
• ❌ Don't: Put all resources in a single monolithic template

Troubleshooting

Problem: The operator skipped the imported context and answered too generically

Symptoms: The result ignores the upstream workflow in plugins/antigravity-awesome-skills/skills/cloudformation-best-practices, fails to mention provenance, or does not use any copied source files at all. Solution: Re-open metadata.json, ORIGIN.md, and the most relevant copied upstream files. Check the external_source block first, then restate the provenance before continuing.

Problem: The imported workflow feels incomplete during review

Symptoms: Reviewers can see the generated SKILL.md, but they cannot quickly tell which references, examples, or scripts matter for the current task. Solution: Point at the exact copied references, examples, scripts, or assets that justify the path you took. If the gap is still real, record it in the PR instead of hiding it.

Problem: The task drifted into a different specialization

Symptoms: The imported skill starts in the right place, but the work turns into debugging, architecture, design, security, or release orchestration that a native skill handles better. Solution: Use the related skills section to hand off deliberately. Keep the imported provenance visible so the next skill inherits the right context instead of starting blind.

Imported Troubleshooting Notes

Imported: Troubleshooting

Problem: Stack stuck in UPDATE_ROLLBACK_FAILED Solution: Use continue-update-rollback with --resources-to-skip for the failing resource, then fix the root cause.

Related Skills

• @00-andruia-consultant - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @00-andruia-consultant-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith - Use when the work is better handled by that native specialization after this imported skill establishes context.
• @10-andruia-skill-smith-v2 - Use when the work is better handled by that native specialization after this imported skill establishes context.

Additional Resources

Use this support matrix and the linked files below as the operator packet for this imported skill. They should reflect real copied source material, not generic scaffolding.