Awesome-omni-skill cloudformation-best-practices

CloudFormation template optimization, nested stacks, drift detection, and production-ready patterns. Use when writing or reviewing CF templates.

install

source · Clone the upstream repo

git clone https://github.com/diegosouzapw/awesome-omni-skill

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/diegosouzapw/awesome-omni-skill "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/devops/cloudformation-best-practices" ~/.claude/skills/diegosouzapw-awesome-omni-skill-cloudformation-best-practices && rm -rf "$T"

manifest: skills/devops/cloudformation-best-practices/SKILL.md

source content

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

Use this skill when

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

Do not use this skill when

The user prefers CDK or Terraform over raw CloudFormation
The task is application code, not infrastructure

Instructions

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

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

✅ 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: Stack stuck in

UPDATE_ROLLBACK_FAILED

Solution: Use

continue-update-rollback

with

--resources-to-skip

for the failing resource, then fix the root cause.