Auto-Documentation

Overview

Generate comprehensive documentation from infrastructure code. This skill creates READMEs, runbooks, and architecture documentation that stays in sync with actual code.

Announce at start: "I'm using the auto-documentation skill to generate documentation."

Documentation Types

1. Module README

For Terraform modules, generate:

# Module: [module-name]

[Brief description of what this module provisions]

## Requirements

| Name | Version |
|------|---------|
| terraform | >= X.Y.Z |
| aws | >= X.Y.Z |

## Providers

| Name | Version |
|------|---------|
| aws | X.Y.Z |

## Resources

| Name | Type |
|------|------|
| aws_instance.this | resource |
| aws_security_group.this | resource |

## Inputs

| Name | Description | Type | Default | Required |
|------|-------------|------|---------|:--------:|
| name | Name prefix for resources | `string` | n/a | yes |
| vpc_id | VPC ID | `string` | n/a | yes |

## Outputs

| Name | Description |
|------|-------------|
| instance_id | ID of the created instance |
| public_ip | Public IP address |

## Usage

```hcl
module "example" {
  source = "./modules/[module-name]"

  name   = "my-instance"
  vpc_id = "vpc-12345"
}

Architecture

[Optional: Mermaid diagram of resources]

Notes

[Any important considerations, limitations, or gotchas]

### 2. Environment Documentation

For environment directories:

```markdown
# Environment: [env-name]

## Overview

[Purpose and scope of this environment]

## Resource Inventory

| Category | Resource Type | Count | Key Resources |
|----------|--------------|-------|---------------|
| Compute | aws_instance | 5 | web-1, web-2, api-1 |
| Database | aws_rds_instance | 2 | primary, replica |
| Network | aws_vpc | 1 | main-vpc |

## Architecture Diagram

```mermaid
graph TB
    subgraph VPC
        subgraph Public
            ALB[Load Balancer]
        end
        subgraph Private
            WEB[Web Servers]
            API[API Servers]
        end
        subgraph Data
            RDS[(Database)]
        end
    end
    ALB --> WEB
    WEB --> API
    API --> RDS

Access Patterns

Dependencies

• [External services or accounts this depends on]

Deployment

[How to deploy changes to this environment]

### 3. Operational Runbook

For operations documentation:

```markdown
# Runbook: [service/component]

## Overview

[What this runbook covers]

## Common Operations

### Starting/Stopping

```bash
# Start the service
terraform apply -target=module.service

# Stop (with caution)
# See "Emergency Procedures" below

Scaling

# Update instance count
terraform apply -var="instance_count=5"

Health Checks

# Check instance status
aws ec2 describe-instance-status --instance-ids i-xxx

# Check application health
curl https://service.example.com/health

Troubleshooting

Problem: High CPU Usage

Symptoms: CPU > 80% sustained

Investigation:

1. Check CloudWatch metrics
2. Review application logs
3. Check for runaway processes

Resolution:

• Scale horizontally if traffic-related
• Restart instance if process issue

Problem: Connection Timeouts

Symptoms: 504 errors at load balancer

Investigation:

1. Check target group health
2. Verify security group rules
3. Check application logs

Resolution:

• [Steps to resolve]

Emergency Procedures

Service Outage

1. Assess: Check CloudWatch alarms
2. Communicate: Notify stakeholders
3. Mitigate: [Immediate actions]
4. Resolve: [Fix steps]
5. Review: Post-incident analysis

Rollback Procedure

# Identify previous state
git log --oneline terraform.tfstate

# Restore previous state (CAREFUL!)
# [State restoration steps]

Contacts

## Process

### Step 1: Analyze Code

```bash
# Find all Terraform files
find . -name "*.tf" -type f

# Extract structure
grep -h "^variable\|^output\|^resource\|^module" *.tf

Step 2: Parse Components

For each file, extract:

• Variables with descriptions and defaults
• Outputs with descriptions
• Resources with types
• Module calls with sources

Step 3: Generate Documentation

Based on directory type:

• Has variables.tf + outputs.tf → Module README
• Named dev/, staging/, prod/ → Environment docs
• Contains operational resources → Include runbook sections

Step 4: Review with User

Always present generated docs for review before writing.

Show:

• What will be created/updated
• Preview of content
• Any gaps or questions

Step 5: Write Files

Only after user approval:

• Write new files
• Update existing files (preserve custom sections)

Best Practices

Keep Docs in Sync

• Regenerate after significant changes
• Use CI to detect doc drift
• Include doc generation in PR checklist

Custom Sections

Mark custom content to preserve during regeneration:

<!-- BEGIN CUSTOM -->
Your custom content here
<!-- END CUSTOM -->

Diagrams

Use Mermaid for architecture diagrams:

• Renders in GitHub/GitLab
• Text-based, version controllable
• Easy to update

Integration with Memory

Store documentation patterns:

• Preferred formats
• Custom sections to preserve
• Team-specific templates