Cisco Router Terraform Configuration

Infrastructure as Code for Cisco IOS XE devices using reusable components

This project provides a modular Terraform configuration for managing Cisco routers via RESTCONF API. Configure VLANs, interfaces, and network segments with validated, reusable components.

🚀 Quick Start

1. Prerequisites

• Cisco IOS XE device with RESTCONF enabled
• Network connectivity to device management interface
• Valid admin credentials
• Terraform >= 1.0 installed

2. Device Setup

Enable RESTCONF on your Cisco device:

configure terminal
restconf
interface GigabitEthernet0/0/1
  ip address 192.168.1.1 255.255.255.0
  no shutdown
exit
ip http server
ip http secure-server
username admin privilege 15 secret cisco123

3. Project Setup

git clone <your-repo>
cd cisco_terraform
cp terraform.tfvars.example terraform.tfvars
# Edit terraform.tfvars with your device credentials

📋 How to Make Changes to Your Router

Option 1: Quick Configuration (Recommended for beginners)

Use the main configuration file for simple setups:

# 1. Configure your credentials
nano terraform.tfvars

# 2. Plan and apply changes
terraform init
terraform plan
terraform apply

Option 2: Port-by-Port Configuration (Recommended for production)

Configure individual ports for isolated, reliable deployments:

# 1. Choose a port to configure
cd ports/port-gi0-1-0  # Internal LAN example

# 2. Review and edit configuration
nano terraform.tfvars  # Edit VLAN, IP addresses, etc.

# 3. Deploy the port
terraform init
terraform plan
terraform apply

Option 3: Parallel Deployment

Configure multiple ports simultaneously:

# Deploy all LAN ports in parallel
cd ports
for port in port-gi0-1-*; do
  (cd "$port" && terraform apply -auto-approve) &
done
wait

🏗️ Project Architecture

graph TB
    subgraph "Project Structure"
        A[main.tf<br/>Complete Router Config]
        B[components/<br/>Reusable Components]
        C[ports/<br/>Individual Port Configs]
        D[shared/<br/>Common Configuration]
    end
    
    subgraph "Components"
        B --> E[interface/]
        B --> F[vlan/]
        B --> G[network/]
        B --> H[port-config/]
        B --> I[provider/]
    end
    
    subgraph "Port Configurations"
        C --> J[port-gi0-1-0/<br/>Internal LAN]
        C --> K[port-gi0-1-1/<br/>DMZ]
        C --> L[port-gi0-1-2/<br/>Guest Network]
        C --> M[port-gi0-1-3/<br/>Server Network]
    end
    
    A --> B
    C --> B
    C --> D
    
    style A fill:#e1f5fe
    style B fill:#f3e5f5
    style C fill:#e8f5e8
    style D fill:#fff3e0

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🔧 Configuration Workflow

flowchart TD
    A[Start: Need to Configure Router] --> B{What type of change?}
    
    B -->|Simple/Learning| C[Use main.tf]
    B -->|Production/Complex| D[Use port-specific configs]
    B -->|New Component| E[Create custom component]
    
    C --> F[Edit terraform.tfvars]
    D --> G[Choose port directory]
    E --> H[Use components/ templates]
    
    F --> I[terraform plan]
    G --> J[Edit port terraform.tfvars]
    H --> K[Test component]
    
    J --> L[terraform plan for port]
    I --> M{Plan looks good?}
    L --> N{Port plan looks good?}
    K --> O{Component works?}
    
    M -->|No| F
    M -->|Yes| P[terraform apply]
    N -->|No| J
    N -->|Yes| Q[terraform apply for port]
    O -->|No| H
    O -->|Yes| R[Document and share]
    
    P --> S[✅ Router Configured]
    Q --> T[✅ Port Configured]
    R --> U[✅ Component Ready]
    
    style A fill:#e3f2fd
    style S fill:#c8e6c9
    style T fill:#c8e6c9
    style U fill:#c8e6c9

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🎯 Common Use Cases

Adding a New VLAN

# Using main.tf approach
nano main.tf  # Add new module block
terraform plan && terraform apply

# Using port-specific approach
cd ports/port-gi0-1-0
nano terraform.tfvars  # Change vlan_id and vlan_name
terraform plan && terraform apply

Changing IP Addresses

cd ports/port-gi0-1-1  # DMZ example
nano terraform.tfvars
# Edit physical_interface_ip and vlan_interface_ip
terraform plan && terraform apply

Creating a New Network Segment

# Copy existing port configuration
cp -r ports/port-gi0-1-0 ports/port-gi0-1-4
cd ports/port-gi0-1-4
nano terraform.tfvars  # Configure new values
terraform init && terraform apply

📊 Network Topology

graph LR
    subgraph "Cisco Router"
        A[GigE0/0/1<br/>Management<br/>192.168.1.1/24]
        
        subgraph "Data Ports"
            B[GigE0/1/0<br/>VLAN 10<br/>Internal LAN<br/>10.10.10.0/24]
            C[GigE0/1/1<br/>VLAN 20<br/>DMZ<br/>10.20.20.0/24]
            D[GigE0/1/2<br/>VLAN 30<br/>Guest<br/>10.30.30.0/24]
            E[GigE0/1/3<br/>VLAN 40<br/>Servers<br/>10.40.40.0/24]
        end
    end
    
    A --> F[Internet/WAN]
    B --> G[Corporate Network]
    C --> H[Public Services]
    D --> I[Guest Users]
    E --> J[Server Farm]
    
    style A fill:#ffeb3b
    style B fill:#4caf50
    style C fill:#ff9800
    style D fill:#2196f3
    style E fill:#9c27b0

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📁 Directory Structure

cisco_terraform/
├── 📄 main.tf                    # Complete router configuration
├── 📄 terraform.tfvars           # Main configuration values
├── 📁 components/                # Reusable components (DRY)
│   ├── 📁 interface/             # Physical interface configuration
│   ├── 📁 vlan/                  # VLAN management
│   ├── 📁 network/               # Complete network segments
│   ├── 📁 port-config/           # High-level port abstraction
│   └── 📄 README.md              # Component documentation
├── 📁 ports/                     # Individual port configurations
│   ├── 📁 port-gi0-1-0/         # Internal LAN (VLAN 10)
│   ├── 📁 port-gi0-1-1/         # DMZ (VLAN 20)
│   ├── 📁 port-gi0-1-2/         # Guest Network (VLAN 30)
│   └── 📁 port-gi0-1-3/         # Server Network (VLAN 40)
└── 📁 shared/                    # Common configuration files
    ├── 📄 versions.tf            # Terraform version requirements
    ├── 📄 provider.tf.template   # Provider configuration template
    └── 📄 variables.tf           # Standard variables

🔍 Configuration Examples

Basic Interface Configuration

module "new_interface" {
  source = "./components/interface"
  
  interface_type = "GigabitEthernet"
  interface_name = "0/2/0"
  description    = "New Interface"
  shutdown       = false
  ipv4_address   = "192.168.50.1"
}

Complete Network Segment

module "new_network" {
  source = "./components/network"
  
  vlan_id                = 50
  vlan_name              = "New_Network"
  interface_name         = "0/2/0"
  interface_description  = "New Network Segment"
  network_cidr           = "10.50.50.0/24"
  physical_interface_ip  = "10.50.50.1"
  vlan_interface_ip      = "10.50.50.254"
}

🛠️ Troubleshooting

Connection Issues

# Test device connectivity
ping 192.168.1.1

# Verify RESTCONF is enabled
curl -k https://192.168.1.1/restconf/data/ietf-yang-library:modules-state

Terraform Issues

# Check configuration syntax
terraform validate

# See detailed plan
terraform plan -detailed-exitcode

# Force refresh state
terraform refresh

# Clean and reinitialize
rm -rf .terraform terraform.tfstate*
terraform init

Configuration Conflicts

# Check current device configuration
terraform show

# Import existing resources
terraform import iosxe_vlan.example 10

# Remove resource from state (danger!)
terraform state rm iosxe_vlan.example

🔐 Security Best Practices

1. Never commit credentials to git
2. Use environment variables for sensitive data:

   export TF_VAR_esr_username="admin"
   export TF_VAR_esr_password="your-password"

3. Enable device logging for audit trails
4. Use separate state files for production
5. Test changes in development environment first

📚 Component Reference

Component	Purpose	Use When
interface/	Configure physical interfaces	Need basic interface setup
vlan/	Manage VLANs and VLAN interfaces	Working with VLANs only
network/	Complete network segments	Setting up full network segment
port-config/	High-level port configuration	Want validation and safety

🤝 Contributing

1. Adding new components: Follow the structure in components/
2. Testing: Validate with terraform validate and terraform plan
3. Documentation: Update this README and component docs
4. Examples: Add working examples to help others

📞 Support

• Documentation: Check components/README.md for component details
• Examples: See working configurations in ports/ directory
• Issues: Review terraform plan output for detailed error messages

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🎉 Ready to configure your router? Start with the Quick Start section above!