terraform-dependency-analyzer

# Terraform Dependency Analyzer

This skill helps analyze and optimize resource dependencies in Terraform configurations.

## When to Use

Use this skill when:
- Understanding resource relationships and dependencies
- Troubleshooting circular dependency errors
- Optimizing resource creation order
- Refactoring complex configurations
- Documenting infrastructure dependencies

## Dependency Types

### Implicit Dependencies

Terraform automatically detects dependencies through resource attribute references:
- Most common and preferred method
- Created when one resource references another's attributes
- Example: `subnet_id = aws_subnet.main.id`

### Explicit Dependencies

Use `depends_on` only when implicit dependencies aren't sufficient:
- Cross-resource timing requirements
- Dependencies not expressed through attributes
- Ensuring proper creation/deletion order
- Should be used sparingly

## Analysis Workflow

### 1. Generate Dependency Graph

```bash
# Create visual dependency graph
terraform graph | dot -Tpng > graph.png

# View as text
terraform graph
```

### 2. Identify Resource Relationships

Parse configuration to map dependencies:
- Read through resource definitions
- Note attribute references between resources
- Identify explicit `depends_on` declarations
- Map out dependency chains

### 3. Check for Circular Dependencies

**Common causes:**
- Security groups with mutual ingress rules
- Resources referencing each other's attributes
- Module outputs creating circular references

**Solution approaches:**
- Break cycles using separate rule resources
- Restructure resource relationships
- Use data sources to break circular references

## Common Dependency Patterns

### VPC Infrastructure
1. VPC → Internet Gateway, Subnets
2. Subnets → NAT Gateway, Route Tables
3. Route Tables → Route Table Associations
4. Security Groups → EC2/RDS instances

### IAM Resources
1. IAM Role → IAM Policy Attachments
2. IAM Role → Resources using the role

### Database Setup
1. VPC, S