# Debian 12 VM Deployment Documentation

## Overview

This document describes the automated deployment process for Debian 12 virtual machines on the grokbox KVM/libvirt hypervisor. The deployment uses cloud-init for unattended configuration and follows the security-first principles outlined in CLAUDE.md.

## Table of Contents

1. [Architecture](#architecture)
2. [Prerequisites](#prerequisites)
3. [Deployment Process](#deployment-process)
4. [Configuration](#configuration)
5. [Security Features](#security-features)
6. [Post-Deployment](#post-deployment)
7. [Troubleshooting](#troubleshooting)
8. [Maintenance](#maintenance)

## Architecture

### Infrastructure Components

```
┌─────────────────────────────────────────────┐
│ grokbox (KVM Hypervisor)                    │
│                                             │
│  ┌──────────────────────────────────────┐  │
│  │ libvirt/QEMU                         │  │
│  │                                      │  │
│  │  ┌────────────────────────────────┐ │  │
│  │  │ Debian 12 Guest VM             │ │  │
│  │  │                                │ │  │
│  │  │ - 2 vCPUs / 2GB RAM           │ │  │
│  │  │ - 20GB qcow2 disk             │ │  │
│  │  │ - cloud-init configured       │ │  │
│  │  │ - ansible user ready          │ │  │
│  │  │ - Security hardened           │ │  │
│  │  └────────────────────────────────┘ │  │
│  │                                      │  │
│  │  Network: virbr0 (192.168.122.0/24) │  │
│  └──────────────────────────────────────┘  │
└─────────────────────────────────────────────┘
```

### Deployment Workflow

```
[Ansible Control Node]
         │
         │ 1. SSH to grokbox
         ▼
   [grokbox hypervisor]
         │
         │ 2. Download Debian cloud image
         ├─ 3. Verify checksums
         ├─ 4. Create VM disk (qcow2)
         ├─ 5. Generate cloud-init ISO
         ├─ 6. Create VM with virt-install
         │
         │ 7. VM boots with cloud-init
         ▼
   [Debian 12 VM]
         │
         ├─ 8. Create ansible user
         ├─ 9. Configure SSH
         ├─ 10. Install packages
         ├─ 11. Security hardening
         └─ 12. System ready
```

## Prerequisites

### Hypervisor Requirements

On **grokbox**, ensure the following are present:

1. **Virtualization Support**
   ```bash
   # Verify CPU virtualization
   egrep -c '(vmx|svm)' /proc/cpuinfo  # Should be > 0

   # Verify KVM module loaded
   lsmod | grep kvm
   ```

2. **Required Packages**
   - libvirt-daemon-system
   - libvirt-clients
   - virtinst
   - qemu-kvm
   - qemu-utils
   - cloud-image-utils
   - genisoimage
   - python3-libvirt

3. **Sufficient Resources**
   - Storage: ~25GB available in `/var/lib/libvirt/images/`
   - Memory: Enough free RAM for VM allocation
   - Network: libvirt default network configured

4. **libvirtd Service Running**
   ```bash
   systemctl status libvirtd
   ```

### Ansible Control Node Requirements

1. Ansible 2.9 or newer
2. SSH access to grokbox hypervisor
3. SSH key configured for grok user
4. Python 3.x installed

### Network Requirements

- Connectivity to Debian cloud image repository
- DNS resolution working
- Default libvirt network (virbr0) configured and active

## Deployment Process

### Step 1: Pre-flight Checks

The playbook performs the following validations:

- **VM Name Uniqueness**: Ensures no VM with the same name exists
- **Virtualization Support**: Validates QEMU/KVM capabilities
- **Package Installation**: Installs required tools if missing
- **Service Status**: Verifies libvirtd is running

### Step 2: Image Management

#### Download Debian Cloud Image

- **Source**: https://cloud.debian.org/images/cloud/bookworm/latest/
- **Image**: debian-12-generic-amd64.qcow2
- **Cache Location**: `/var/lib/libvirt/images/debian-12-generic-amd64.qcow2`
- **Checksum Verification**: SHA512SUMS validated

The base image is downloaded once and cached for subsequent deployments.

#### Create VM Disk

A new copy-on-write (CoW) disk is created using qemu-img:

```bash
qemu-img create -f qcow2 \
  -F qcow2 \
  -b /var/lib/libvirt/images/debian-12-generic-amd64.qcow2 \
  /var/lib/libvirt/images/debian12-guest.qcow2 \
  20G
```

This creates a thin-provisioned disk backed by the cloud image.

### Step 3: Cloud-Init Configuration

Two configuration files are generated:

#### meta-data
```yaml
instance-id: debian12-guest
local-hostname: debian12
```

#### user-data
Comprehensive cloud-init configuration including:

- **User Management**: Creates ansible user with SSH keys
- **Security Configuration**: SSH hardening, firewall setup
- **Package Installation**: Essential and security packages
- **System Configuration**: Time sync, locale, timezone
- **Automatic Updates**: Unattended security upgrades

#### ISO Generation

The configuration files are packaged into a bootable ISO:

```bash
genisoimage -output debian12-guest-cloud-init.iso \
  -volid cidata -joliet -rock \
  user-data meta-data
```

### Step 4: VM Creation

VM is created using virt-install:

```bash
virt-install \
  --name debian12-guest \
  --memory 2048 \
  --vcpus 2 \
  --disk path=/var/lib/libvirt/images/debian12-guest.qcow2,format=qcow2,bus=virtio \
  --disk path=/var/lib/libvirt/images/debian12-guest-cloud-init.iso,device=cdrom \
  --network network=default,model=virtio \
  --os-variant debian11 \
  --graphics none \
  --console pty,target_type=serial \
  --import \
  --noautoconsole
```

### Step 5: Boot and Initialization

1. **VM Boots**: Starts from the qcow2 disk
2. **Cloud-Init Runs**: Reads configuration from ISO
3. **System Configuration**: Applies all settings
4. **Network Configuration**: Obtains IP via DHCP
5. **Package Updates**: Downloads and installs updates
6. **Service Initialization**: Starts all configured services

**Typical boot time**: 60-90 seconds

### Step 6: Validation

The playbook validates:

- VM is running and accessible
- IP address assigned
- SSH port (22) accepting connections
- cloud-init completed successfully
- System resources available

### Step 7: Post-Deployment Configuration

Optional second play that:

- Waits for cloud-init completion
- Gathers system facts
- Displays system information
- Validates disk and memory usage

## Configuration

### Default Configuration

```yaml
# VM Specifications
vm_name: "debian12-guest"
vm_hostname: "debian12"
vm_domain: "localdomain"
vm_vcpus: 2
vm_memory_mb: 2048
vm_disk_size_gb: 20

# Network
vm_network: "default"
vm_bridge: "virbr0"

# Storage
vm_disk_path: "/var/lib/libvirt/images/{{ vm_name }}.qcow2"
cloud_init_iso_path: "/var/lib/libvirt/images/{{ vm_name }}-cloud-init.iso"
```

### Customization Examples

#### High-Performance VM

```bash
ansible-playbook plays/deploy-debian12-vm.yml \
  -e "vm_name=app-server" \
  -e "vm_vcpus=8" \
  -e "vm_memory_mb=16384" \
  -e "vm_disk_size_gb=100"
```

#### Development VM

```bash
ansible-playbook plays/deploy-debian12-vm.yml \
  -e "vm_name=dev-workstation" \
  -e "vm_vcpus=4" \
  -e "vm_memory_mb=8192" \
  -e "vm_disk_size_gb=50" \
  -e "vm_hostname=devbox" \
  -e "vm_domain=dev.local"
```

#### Custom SSH Key

```bash
ansible-playbook plays/deploy-debian12-vm.yml \
  -e "vm_name=secure-vm" \
  -e "ansible_user_ssh_key='ssh-ed25519 AAAA...'"
```

### Variable Precedence

Variables can be set in order of precedence:

1. **Command-line** (`-e` flag) - Highest
2. **Playbook vars section**
3. **Inventory host_vars**
4. **Inventory group_vars**
5. **Defaults in playbook** - Lowest

## Security Features

### User Management

- **ansible user**: Non-root service account
  - Passwordless sudo access
  - SSH key authentication only
  - Member of sudo group
  - Home directory: `/home/ansible`

- **root user**: Console access only
  - SSH login disabled
  - Password set for emergency console access
  - Remote access blocked

### SSH Hardening

Configuration in `/etc/ssh/sshd_config.d/99-security.conf`:

```
PermitRootLogin no
PasswordAuthentication no
PubkeyAuthentication yes
MaxAuthTries 3
MaxSessions 10
ClientAliveInterval 300
ClientAliveCountMax 2
```

### Firewall Configuration

- **UFW (Uncomplicated Firewall)** enabled by default
- Default policy: deny incoming, allow outgoing
- SSH (port 22) allowed
- Additional rules can be added post-deployment

### Automatic Security Updates

Unattended-upgrades configured for:

- Automatic installation of security updates
- Daily update checks
- Automatic cleanup of old kernels
- Email notifications (if configured)
- **No automatic reboot** (requires manual intervention)

### Audit and Monitoring

- **auditd**: System call auditing enabled
- **aide**: File integrity monitoring installed
- **chrony**: Time synchronization configured
- **Logging**: All cloud-init output logged

### Compliance Features

Aligned with CLAUDE.md security requirements:

- ✅ Principle of least privilege
- ✅ Encryption in transit (SSH)
- ✅ Key-based authentication
- ✅ Automated security updates
- ✅ System auditing enabled
- ✅ Time synchronization
- ✅ Firewall enabled by default

## Post-Deployment

### Adding to Inventory

Update your Ansible inventory:

```yaml
# inventories/development/hosts.yml
kvm_guests:
  children:
    application_servers:
      hosts:
        debian12-guest:
          ansible_host: 192.168.122.X
          ansible_user: ansible
          ansible_ssh_common_args: '-o ProxyJump=grokbox -o StrictHostKeyChecking=accept-new'
          ansible_python_interpreter: /usr/bin/python3
          host_description: "Application Server - Debian 12"
          host_role: application
          host_type: virtual_machine
          hypervisor: grokbox
          vm_vcpus: 2
          vm_memory_mb: 2048
          autostart: true
```

### Initial Access

```bash
# Get VM IP address
ssh grokbox "virsh domifaddr debian12-guest"

# SSH to VM via ProxyJump
ssh -J grokbox ansible@192.168.122.X

# Or add to ~/.ssh/config
Host debian12-guest
    HostName 192.168.122.X
    User ansible
    ProxyJump grokbox
    StrictHostKeyChecking accept-new
```

### Configuration Management

Run additional roles or playbooks:

```bash
# Example: Configure web server
ansible-playbook -i inventories/development/hosts.yml \
  playbooks/configure-webserver.yml \
  -l debian12-guest

# Example: Security hardening
ansible-playbook -i inventories/development/hosts.yml \
  playbooks/security-hardening.yml \
  -l debian12-guest
```

### VM Management Commands

```bash
# Start VM
virsh start debian12-guest

# Shutdown VM gracefully
virsh shutdown debian12-guest

# Force shutdown
virsh destroy debian12-guest

# Reboot VM
virsh reboot debian12-guest

# Enable autostart
virsh autostart debian12-guest

# Disable autostart
virsh autostart debian12-guest --disable

# VM status
virsh dominfo debian12-guest

# VM resource usage
virsh domstats debian12-guest

# Console access
virsh console debian12-guest
```

## Troubleshooting

### Common Issues

#### 1. VM Already Exists

**Error**: VM with name already exists

**Solution**:
```bash
# Check existing VMs
virsh list --all

# Remove existing VM
virsh destroy debian12-guest  # if running
virsh undefine debian12-guest --remove-all-storage
```

#### 2. Image Download Fails

**Error**: Failed to download cloud image

**Causes**:
- Network connectivity issues
- Proxy configuration
- DNS resolution problems

**Solution**:
```bash
# Test connectivity
curl -I https://cloud.debian.org

# Manual download
cd /var/lib/libvirt/images
wget https://cloud.debian.org/images/cloud/bookworm/latest/debian-12-generic-amd64.qcow2

# Re-run playbook
ansible-playbook plays/deploy-debian12-vm.yml -t deploy
```

#### 3. VM Won't Get IP Address

**Error**: IP address not assigned after 10 retries

**Causes**:
- DHCP server not running
- Network misconfiguration
- VM network interface issues

**Solution**:
```bash
# Check libvirt network
virsh net-list --all
virsh net-info default
virsh net-start default  # if not started

# Check VM network interface
virsh domiflist debian12-guest

# Check DHCP leases
virsh net-dhcp-leases default

# Access console to troubleshoot
virsh console debian12-guest
# Check: ip addr, systemctl status networking
```

#### 4. SSH Connection Failed

**Error**: SSH connection timeout or refused

**Causes**:
- SSH service not started
- Firewall blocking
- Wrong IP address
- cloud-init not completed

**Solution**:
```bash
# Verify VM is running
virsh list

# Check cloud-init status via console
virsh console debian12-guest
# Run: cloud-init status --wait

# Check SSH service
# Via console: systemctl status ssh

# Check firewall
# Via console: ufw status

# Verify SSH key
ssh-add -l
```

#### 5. Insufficient Resources

**Error**: Failed to allocate memory or storage

**Solution**:
```bash
# Check available resources
free -h
df -h /var/lib/libvirt/images/

# Adjust VM resources
ansible-playbook plays/deploy-debian12-vm.yml \
  -e "vm_memory_mb=1024" \
  -e "vm_disk_size_gb=10"
```

### Debug Mode

Enable verbose logging:

```bash
# Ansible verbose mode
ansible-playbook plays/deploy-debian12-vm.yml -vvv

# Check cloud-init logs on VM
virsh console debian12-guest
# Then: tail -f /var/log/cloud-init-output.log

# Check libvirt logs
journalctl -u libvirtd -f
```

### Health Checks

```bash
# Verify VM health
virsh dominfo debian12-guest
virsh domstats debian12-guest

# Network connectivity
ping $(virsh domifaddr debian12-guest | grep -oP '(\d{1,3}\.){3}\d{1,3}' | head -1)

# SSH connectivity
ssh -J grokbox ansible@$(virsh domifaddr debian12-guest | grep -oP '(\d{1,3}\.){3}\d{1,3}' | head -1) "echo 'VM is accessible'"
```

## Maintenance

### Updating the Base Image

Periodically update the cached Debian cloud image:

```bash
# Remove old image
ssh grokbox "rm /var/lib/libvirt/images/debian-12-generic-amd64.qcow2"

# Download latest
ansible-playbook plays/deploy-debian12-vm.yml -t download,verify
```

### VM Snapshots

Create snapshots before major changes:

```bash
# Create snapshot
virsh snapshot-create-as debian12-guest \
  snapshot1 \
  "Before application deployment"

# List snapshots
virsh snapshot-list debian12-guest

# Revert to snapshot
virsh snapshot-revert debian12-guest snapshot1

# Delete snapshot
virsh snapshot-delete debian12-guest snapshot1
```

### Backup and Restore

#### Backup VM

```bash
# Stop VM
virsh shutdown debian12-guest

# Backup disk
cp /var/lib/libvirt/images/debian12-guest.qcow2 \
   /backup/debian12-guest-$(date +%Y%m%d).qcow2

# Backup XML config
virsh dumpxml debian12-guest > /backup/debian12-guest.xml

# Start VM
virsh start debian12-guest
```

#### Restore VM

```bash
# Copy disk back
cp /backup/debian12-guest-20241110.qcow2 \
   /var/lib/libvirt/images/debian12-guest.qcow2

# Define VM from XML
virsh define /backup/debian12-guest.xml

# Start VM
virsh start debian12-guest
```

### Resize VM Disk

```bash
# Shutdown VM
virsh shutdown debian12-guest

# Resize disk
qemu-img resize /var/lib/libvirt/images/debian12-guest.qcow2 +10G

# Start VM
virsh start debian12-guest

# On VM: resize partition and filesystem
growpart /dev/vda 1
resize2fs /dev/vda1
```

### Resource Adjustment

Modify VM resources:

```bash
# Set maximum memory (requires shutdown)
virsh setmaxmem debian12-guest 4194304 --config

# Set current memory (can be done live)
virsh setmem debian12-guest 4194304

# Set vCPUs (requires shutdown)
virsh setvcpus debian12-guest 4 --config --maximum
virsh setvcpus debian12-guest 4 --config
```

## Best Practices

1. **Naming Convention**: Use descriptive VM names indicating purpose
2. **Resource Planning**: Right-size VMs to avoid waste
3. **Documentation**: Document VM purpose and configuration
4. **Monitoring**: Set up monitoring for critical VMs
5. **Backups**: Regular backups of important VMs
6. **Updates**: Keep VMs updated with security patches
7. **Inventory**: Maintain accurate Ansible inventory
8. **Tags**: Use libvirt tags for organization
9. **Networking**: Use appropriate network isolation
10. **Testing**: Test deployment process in development first

## References

- [CLAUDE.md](../CLAUDE.md) - Infrastructure guidelines
- [Cheatsheet](../cheatsheets/deploy-debian12-vm.md) - Quick reference
- [Debian Cloud Images](https://cloud.debian.org/images/cloud/)
- [cloud-init Documentation](https://cloudinit.readthedocs.io/)
- [libvirt Documentation](https://libvirt.org/docs.html)
- [virt-install man page](https://linux.die.net/man/1/virt-install)

## Support and Contact

For issues or questions:

1. Check troubleshooting section above
2. Review cloud-init logs: `/var/log/cloud-init.log`
3. Review libvirt logs: `journalctl -u libvirtd`
4. Consult Ansible playbook: `plays/deploy-debian12-vm.yml`

---

**Document Version**: 1.0
**Last Updated**: 2025-11-10
**Maintained By**: Ansible Infrastructure Team