# Multi-Distribution Linux VM Deployment Documentation

## Overview

This document describes the automated deployment process for multiple Linux distributions on KVM/libvirt hypervisors. The deployment supports major server distributions including Debian, Ubuntu, RHEL, CentOS Stream, Rocky Linux, AlmaLinux, SLES, and openSUSE Leap.

## Table of Contents

1. [Supported Distributions](#supported-distributions)
2. [Architecture](#architecture)
3. [Prerequisites](#prerequisites)
4. [Cloud Image Sources](#cloud-image-sources)
5. [Deployment Process](#deployment-process)
6. [Distribution-Specific Configuration](#distribution-specific-configuration)
7. [Security Features](#security-features)
8. [Post-Deployment](#post-deployment)
9. [Troubleshooting](#troubleshooting)
10. [Best Practices](#best-practices)

## Supported Distributions

### Debian Family

| Distribution | Version | Package Manager | Firewall | Cloud Image |
|--------------|---------|----------------|----------|-------------|
| Debian | 11 (Bullseye) | apt | ufw | ✅ Auto-download |
| Debian | 12 (Bookworm) | apt | ufw | ✅ Auto-download |
| Ubuntu | 20.04 LTS (Focal) | apt | ufw | ✅ Auto-download |
| Ubuntu | 22.04 LTS (Jammy) | apt | ufw | ✅ Auto-download |
| Ubuntu | 24.04 LTS (Noble) | apt | ufw | ✅ Auto-download |

### RHEL Family

| Distribution | Version | Package Manager | Firewall | SELinux | Cloud Image |
|--------------|---------|----------------|----------|---------|-------------|
| RHEL | 8, 9 | dnf | firewalld | Enforcing | ⚠️ Manual download |
| CentOS Stream | 8, 9 | dnf | firewalld | Enforcing | ✅ Auto-download |
| Rocky Linux | 8, 9 | dnf | firewalld | Enforcing | ✅ Auto-download |
| AlmaLinux | 8, 9 | dnf | firewalld | Enforcing | ✅ Auto-download |

### SUSE Family

| Distribution | Version | Package Manager | Firewall | Cloud Image |
|--------------|---------|----------------|----------|-------------|
| SLES | 15 | zypper | firewalld | ⚠️ Manual download |
| openSUSE Leap | 15.5, 15.6 | zypper | firewalld | ✅ Auto-download |

**Legend:**
- ✅ = Automatically downloaded from official repositories
- ⚠️ = Requires subscription and manual download

## Architecture

### Multi-Distribution Support Design

```
┌─────────────────────────────────────────────────────────┐
│ Ansible Control Node                                    │
│                                                          │
│  ┌────────────────────────────────────────────────┐    │
│  │ deploy-linux-vm.yml                             │    │
│  │                                                 │    │
│  │  • Distribution Selection Logic                │    │
│  │  • Cloud Image Repository Map                  │    │
│  │  • OS Family Detection                         │    │
│  │  • Package Manager Adaptation                  │    │
│  └────────────────────────────────────────────────┘    │
└─────────────────────────────────────────────────────────┘
                         │
                         │ SSH
                         ▼
┌─────────────────────────────────────────────────────────┐
│ KVM Hypervisor (grokbox)                                │
│                                                          │
│  ┌──────────────────────────────────────────────┐      │
│  │ Cloud Image Cache                             │      │
│  │ /var/lib/libvirt/images/                     │      │
│  │  ├─ debian-12-*.qcow2                        │      │
│  │  ├─ ubuntu-22.04-*.img                       │      │
│  │  ├─ centos-stream-9-*.qcow2                  │      │
│  │  ├─ rocky-9-*.qcow2                          │      │
│  │  └─ almalinux-9-*.qcow2                      │      │
│  └──────────────────────────────────────────────┘      │
│                                                          │
│  ┌──────────────────────────────────────────────┐      │
│  │ libvirt/QEMU                                  │      │
│  │                                               │      │
│  │  ┌──────────────┐  ┌──────────────┐         │      │
│  │  │ Debian VM    │  │ Ubuntu VM    │         │      │
│  │  │ ufw enabled  │  │ ufw enabled  │         │      │
│  │  └──────────────┘  └──────────────┘         │      │
│  │                                               │      │
│  │  ┌──────────────┐  ┌──────────────┐         │      │
│  │  │ Rocky VM     │  │ Alma VM      │         │      │
│  │  │ SELinux=Enf  │  │ SELinux=Enf  │         │      │
│  │  │ firewalld    │  │ firewalld    │         │      │
│  │  └──────────────┘  └──────────────┘         │      │
│  └──────────────────────────────────────────────┘      │
└─────────────────────────────────────────────────────────┘
```

### Deployment Workflow

```
[Start]
   │
   ▼
[Validate Distribution Selection]
   │
   ├─ Check distribution in supported list
   ├─ Set distribution facts (family, package manager, etc.)
   └─ Display deployment configuration
   │
   ▼
[Pre-flight Checks]
   │
   ├─ Verify VM doesn't already exist
   ├─ Validate virtualization support
   └─ Install required packages on hypervisor
   │
   ▼
[Download Cloud Image]
   │
   ├─ Check if image cached
   ├─ Download from official repository
   └─ Verify checksum (SHA256/SHA512)
   │
   ▼
[Create VM Storage]
   │
   ├─ Create qcow2 disk (CoW from base image)
   └─ Set proper permissions (libvirt-qemu/qemu)
   │
   ▼
[Generate Cloud-Init Configuration]
   │
   ├─ Select template based on OS family:
   │   ├─ Debian/Ubuntu → apt, ufw, unattended-upgrades
   │   ├─ RHEL family → dnf, firewalld, SELinux, dnf-automatic
   │   └─ SUSE family → zypper, firewalld
   │
   ├─ Create meta-data (hostname, instance-id)
   ├─ Create user-data (users, packages, security)
   └─ Generate cloud-init ISO
   │
   ▼
[Deploy VM]
   │
   ├─ Run virt-install with appropriate os-variant
   ├─ Attach disk and cloud-init ISO
   └─ Start VM
   │
   ▼
[Wait for Boot]
   │
   ├─ VM boots from qcow2 disk
   ├─ Cloud-init runs configuration
   ├─ Network configured via DHCP
   └─ Get IP address from libvirt
   │
   ▼
[Validation]
   │
   ├─ Test SSH connectivity
   ├─ Verify cloud-init completion
   ├─ Display VM information
   └─ System health checks
   │
   ▼
[Cleanup]
   │
   └─ Remove temporary files
   │
   ▼
[Complete]
```

## Prerequisites

### Hypervisor Requirements

**Hardware:**
- CPU with virtualization extensions (Intel VT-x or AMD-V)
- Sufficient RAM for host + guest VMs
- Adequate storage for cloud images and VM disks

**Software:**

**For Debian/Ubuntu hypervisors:**
```bash
apt install -y \
  libvirt-daemon-system \
  libvirt-clients \
  virtinst \
  qemu-kvm \
  qemu-utils \
  cloud-image-utils \
  genisoimage \
  python3-libvirt
```

**For RHEL/CentOS/Rocky/Alma hypervisors:**
```bash
dnf install -y \
  libvirt \
  libvirt-client \
  virt-install \
  qemu-kvm \
  qemu-img \
  cloud-utils \
  genisoimage \
  python3-libvirt
```

**Services:**
```bash
systemctl enable --now libvirtd
```

### Network Requirements

- Internet connectivity for cloud image downloads
- DNS resolution working
- libvirt default network active:
  ```bash
  virsh net-list
  virsh net-start default  # if not started
  virsh net-autostart default
  ```

### Ansible Control Node

- Ansible 2.9 or newer
- SSH access to hypervisor
- Python 3.x installed

## Cloud Image Sources

### Official Repositories

**Debian:**
- URL: https://cloud.debian.org/images/cloud/
- Format: qcow2
- Checksum: SHA512SUMS provided
- Update Frequency: Regular (stable releases)

**Ubuntu:**
- URL: https://cloud-images.ubuntu.com/
- Format: img (qcow2 compatible)
- Checksum: SHA256SUMS provided
- Update Frequency: Daily builds available

**CentOS Stream:**
- URL: https://cloud.centos.org/centos/
- Format: qcow2
- Checksum: SHA256 CHECKSUM file
- Update Frequency: Regular updates

**Rocky Linux:**
- URL: https://download.rockylinux.org/pub/rocky/
- Format: qcow2
- Checksum: SHA256 CHECKSUM file
- Update Frequency: Regular with point releases

**AlmaLinux:**
- URL: https://repo.almalinux.org/almalinux/
- Format: qcow2
- Checksum: SHA256 CHECKSUM file
- Update Frequency: Regular with point releases

**openSUSE Leap:**
- URL: https://download.opensuse.org/distribution/leap/
- Format: qcow2
- Checksum: SHA256 per-file
- Update Frequency: Per release cycle

### Manual Download Required

**Red Hat Enterprise Linux (RHEL):**
- Requires: Red Hat subscription
- Portal: https://access.redhat.com/downloads/
- Steps:
  1. Log in to Red Hat Customer Portal
  2. Navigate to Downloads
  3. Select "Red Hat Enterprise Linux"
  4. Download KVM Guest Image
  5. Place at: `/var/lib/libvirt/images/rhel-X-x86_64-kvm.qcow2`

**SUSE Linux Enterprise Server (SLES):**
- Requires: SUSE subscription
- Portal: https://scc.suse.com/
- Steps:
  1. Log in to SUSE Customer Center
  2. Download cloud image for SLES 15
  3. Place at: `/var/lib/libvirt/images/sles-15-genericcloud-amd64.qcow2`

## Deployment Process

### Basic Deployment

```bash
ansible-playbook plays/deploy-linux-vm.yml \
  -e "os_distribution=<distro-version>" \
  -e "vm_name=<name>"
```

### Distribution Selection

The `os_distribution` variable determines which Linux distribution to deploy. Format: `distro-version`

**Examples:**
```bash
# Debian
-e "os_distribution=debian-12"

# Ubuntu
-e "os_distribution=ubuntu-22.04"

# CentOS Stream
-e "os_distribution=centos-stream-9"

# Rocky Linux
-e "os_distribution=rocky-9"

# AlmaLinux
-e "os_distribution=almalinux-9"

# openSUSE
-e "os_distribution=opensuse-leap-15.6"
```

### Resource Customization

```bash
ansible-playbook plays/deploy-linux-vm.yml \
  -e "os_distribution=rocky-9" \
  -e "vm_name=database-server" \
  -e "vm_hostname=db01" \
  -e "vm_domain=production.local" \
  -e "vm_vcpus=8" \
  -e "vm_memory_mb=16384" \
  -e "vm_disk_size_gb=200"
```

### Configuration Variables

| Variable | Type | Default | Description |
|----------|------|---------|-------------|
| `os_distribution` | **Required** | debian-12 | Distribution identifier |
| `vm_name` | String | linux-guest | VM name in libvirt |
| `vm_hostname` | String | linux-vm | Guest hostname |
| `vm_domain` | String | localdomain | DNS domain |
| `vm_vcpus` | Integer | 2 | Number of virtual CPUs |
| `vm_memory_mb` | Integer | 2048 | RAM in megabytes |
| `vm_disk_size_gb` | Integer | 20 | Disk size in gigabytes |
| `vm_network` | String | default | Libvirt network name |
| `vm_bridge` | String | virbr0 | Bridge interface |
| `ansible_user_ssh_key` | String | (preset) | SSH public key for ansible user |

## Distribution-Specific Configuration

### Debian/Ubuntu Systems

**Package Manager:** apt

**Cloud-Init Packages:**
- sudo, vim, htop, tmux, curl, wget, rsync, git
- python3, python3-pip, jq, bc
- aide, auditd, chrony, ufw, lvm2
- cloud-guest-utils, parted
- unattended-upgrades, apt-listchanges

**Security Configuration:**
- **Firewall:** ufw enabled, SSH allowed
- **SSH:** Root login disabled, key-only auth
- **Updates:** unattended-upgrades for security updates
- **Audit:** auditd enabled
- **Time Sync:** chrony configured

**User Management:**
- ansible user → member of `sudo` group
- Passwordless sudo access

**Automatic Updates Configuration:**
```
/etc/apt/apt.conf.d/50unattended-upgrades
/etc/apt/apt.conf.d/20auto-upgrades
```

**Post-Boot Commands:**
```bash
systemctl enable ssh && systemctl restart ssh
systemctl enable chrony && systemctl start chrony
ufw --force enable && ufw allow ssh
systemctl enable auditd && systemctl start auditd
growpart /dev/vda 1 && resize2fs /dev/vda1
```

### RHEL Family Systems

**Package Manager:** dnf

**Cloud-Init Packages:**
- sudo, vim, htop, tmux, curl, wget, rsync, git
- python3, python3-pip, jq, bc
- aide, audit, chrony, firewalld, lvm2
- cloud-utils-growpart, gdisk
- dnf-automatic
- policycoreutils-python-utils

**Security Configuration:**
- **Firewall:** firewalld enabled, SSH service allowed
- **SELinux:** Enforcing mode
- **SSH:** Root login disabled, key-only auth
- **Updates:** dnf-automatic for security updates
- **Audit:** auditd enabled
- **Time Sync:** chronyd configured

**User Management:**
- ansible user → member of `wheel` group
- Passwordless sudo access

**SELinux Configuration:**
```bash
setenforce 1
sed -i 's/^SELINUX=.*/SELINUX=enforcing/' /etc/selinux/config
```

**Automatic Updates Configuration:**
```
/etc/dnf/automatic.conf
  upgrade_type = security
  apply_updates = yes
```

**Post-Boot Commands:**
```bash
systemctl enable sshd && systemctl restart sshd
systemctl enable chronyd && systemctl start chronyd
systemctl enable firewalld && systemctl start firewalld
firewall-cmd --permanent --add-service=ssh && firewall-cmd --reload
systemctl enable auditd && systemctl start auditd
systemctl enable dnf-automatic.timer && systemctl start dnf-automatic.timer
setenforce 1
growpart /dev/vda 1 && xfs_growfs /
```

### SUSE Family Systems

**Package Manager:** zypper

**Cloud-Init Packages:**
- sudo, vim, htop, tmux, curl, wget, rsync, git
- python3, python3-pip, jq, bc
- aide, audit, chrony, firewalld, lvm2
- cloud-utils-growpart, gdisk

**Security Configuration:**
- **Firewall:** firewalld enabled, SSH service allowed
- **SSH:** Root login disabled, key-only auth
- **Audit:** auditd enabled
- **Time Sync:** chronyd configured

**User Management:**
- ansible user → member of `wheel` group
- Passwordless sudo access

**Post-Boot Commands:**
```bash
systemctl enable sshd && systemctl restart sshd
systemctl enable chronyd && systemctl start chronyd
systemctl enable firewalld && systemctl start firewalld
firewall-cmd --permanent --add-service=ssh && firewall-cmd --reload
systemctl enable auditd && systemctl start auditd
growpart /dev/vda 1 && xfs_growfs / || resize2fs /dev/vda1 || btrfs filesystem resize max /
```

## Security Features

### Universal Security Measures

All deployed VMs, regardless of distribution, include:

1. **User Security:**
   - Dedicated `ansible` service account
   - SSH key-based authentication only
   - Passwordless sudo (with logging)
   - Root SSH login disabled
   - Emergency console access available (password: ChangeMe123!)

2. **Network Security:**
   - Host-based firewall enabled and configured
   - SSH service allowed
   - Default deny policy for incoming traffic
   - Outgoing traffic allowed

3. **System Security:**
   - Audit daemon (auditd) enabled
   - Automatic security updates configured
   - Time synchronization enabled (chrony)
   - File integrity monitoring installed (AIDE)
   - Secure SSH configuration applied

4. **SSH Hardening:**
   ```
   PermitRootLogin no
   PasswordAuthentication no
   PubkeyAuthentication yes
   MaxAuthTries 3
   MaxSessions 10
   ClientAliveInterval 300
   ClientAliveCountMax 2
   ```

### Distribution-Specific Security

**RHEL Family:**
- SELinux in enforcing mode
- firewalld with rich rules support
- dnf-automatic for security updates
- Subscription management for certified packages (RHEL)

**Debian/Ubuntu:**
- AppArmor profiles (Ubuntu)
- UFW for simplified firewall management
- unattended-upgrades for security updates
- Automatic security patch installation

**SUSE Family:**
- AppArmor support
- firewalld with zones
- YaST integration for security management

### Compliance Alignment

The deployment follows CLAUDE.md security principles:

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

## Post-Deployment

### Adding to Ansible Inventory

**Debian/Ubuntu VM:**
```yaml
debian_servers:
  hosts:
    debian12-vm:
      ansible_host: 192.168.122.X
      ansible_user: ansible
      ansible_ssh_common_args: '-o ProxyJump=grokbox -o StrictHostKeyChecking=accept-new'
      os_distribution: debian-12
      os_family: debian
      package_manager: apt
```

**RHEL Family VM:**
```yaml
rhel_servers:
  hosts:
    rocky9-vm:
      ansible_host: 192.168.122.X
      ansible_user: ansible
      ansible_ssh_common_args: '-o ProxyJump=grokbox -o StrictHostKeyChecking=accept-new'
      os_distribution: rocky-9
      os_family: rhel
      package_manager: dnf
      selinux_mode: enforcing
```

### Initial Configuration

After deployment, run configuration management:

```bash
# Update system packages
ansible <vm_name> -m package -a "name=* state=latest" -b

# Install additional packages
ansible <vm_name> -m package -a "name=nginx state=present" -b

# Run configuration playbooks
ansible-playbook -i inventories/development/hosts.yml \
  playbooks/configure-webserver.yml \
  -l <vm_name>
```

### Verification Steps

1. **SSH Access:**
   ```bash
   ssh -J grokbox ansible@<VM_IP>
   ```

2. **Cloud-Init Status:**
   ```bash
   cloud-init status --wait
   cloud-init status --long
   ```

3. **System Information:**
   ```bash
   cat /etc/os-release
   uname -r
   ```

4. **Security Checks:**
   ```bash
   # Firewall
   sudo ufw status verbose  # Debian/Ubuntu
   sudo firewall-cmd --list-all  # RHEL/SUSE

   # SELinux (RHEL family)
   getenforce

   # Audit daemon
   sudo systemctl status auditd

   # Automatic updates
   sudo systemctl status unattended-upgrades  # Debian/Ubuntu
   sudo systemctl status dnf-automatic.timer  # RHEL
   ```

5. **Disk and Memory:**
   ```bash
   df -h
   free -h
   lsblk
   ```

## Troubleshooting

### Distribution Selection Issues

**Problem:** Invalid distribution error

**Solution:**
```bash
# List supported distributions
grep "^      " plays/deploy-linux-vm.yml | grep -E "debian-|ubuntu-|rhel-|centos-|rocky-|alma|sles-|opensuse"

# Use exact distribution identifier
-e "os_distribution=debian-12"  # Correct
-e "os_distribution=debian"     # Wrong
```

### Cloud Image Download Failures

**Problem:** Image download fails or times out

**Causes:**
- Network connectivity issues
- Repository temporarily unavailable
- Proxy configuration needed

**Solutions:**
```bash
# Test connectivity
curl -I https://cloud.debian.org/
curl -I https://cloud-images.ubuntu.com/

# Manual download
cd /var/lib/libvirt/images
wget <cloud_image_url>

# Configure proxy (if needed)
export https_proxy=http://proxy:port
```

### Checksum Verification Failures

**Problem:** Checksum verification fails

**Causes:**
- Corrupt download
- Mismatch between image and checksum file
- Wrong checksum type

**Solutions:**
```bash
# Re-download image
rm /var/lib/libvirt/images/<image-name>
ansible-playbook plays/deploy-linux-vm.yml -e "os_distribution=..." -t download

# Verify manually
cd /var/lib/libvirt/images
sha256sum <image-name>
# Compare with checksum file
```

### VM Boot Issues

**Problem:** VM created but won't boot or get IP

**Causes:**
- Cloud-init configuration error
- Network misconfiguration
- Insufficient resources

**Solutions:**
```bash
# Check VM status
virsh list --all
virsh dominfo <vm_name>

# View console
virsh console <vm_name>

# Check cloud-init logs (via console)
tail -f /var/log/cloud-init-output.log
journalctl -u cloud-init

# Restart VM
virsh destroy <vm_name>
virsh start <vm_name>
```

### SSH Connection Issues

**Problem:** Cannot SSH to deployed VM

**Causes:**
- SSH key not configured correctly
- Firewall blocking
- cloud-init not completed
- Wrong IP address

**Solutions:**
```bash
# Verify IP address
virsh domifaddr <vm_name>

# Test connectivity
ping <VM_IP>

# Check SSH service via console
virsh console <vm_name>
# Then: systemctl status ssh|sshd

# Verify firewall
# Via console:
sudo ufw status  # Debian/Ubuntu
sudo firewall-cmd --list-all  # RHEL/SUSE

# Check cloud-init completion
# Via console:
cloud-init status --wait
```

### SELinux Issues (RHEL Family)

**Problem:** Services failing due to SELinux denials

**Solutions:**
```bash
# Check SELinux status
getenforce
sestatus

# View denials
sudo ausearch -m avc -ts recent

# Temporarily set to permissive (troubleshooting only)
sudo setenforce 0

# Generate policy from denials
sudo ausearch -m avc -ts recent | audit2allow -M myapp
sudo semodule -i myapp.pp

# Re-enable enforcing
sudo setenforce 1
```

### Package Manager Issues

**Debian/Ubuntu:**
```bash
# Update package cache
sudo apt update

# Fix broken packages
sudo apt --fix-broken install

# Clear cache
sudo apt clean
```

**RHEL Family:**
```bash
# Update metadata
sudo dnf makecache

# Check for problems
sudo dnf check

# Clean cache
sudo dnf clean all
```

**SUSE:**
```bash
# Refresh repositories
sudo zypper refresh

# Verify
sudo zypper verify

# Clean cache
sudo zypper clean
```

## Best Practices

### Distribution Selection

1. **Use LTS versions for production:**
   - Ubuntu 22.04 LTS (support until 2027)
   - Ubuntu 24.04 LTS (support until 2029)
   - RHEL/Rocky/Alma 9 (support until 2032)

2. **Match distribution to workload:**
   - Web servers: Ubuntu, Debian
   - Enterprise applications: RHEL, Rocky Linux, AlmaLinux
   - Container hosts: CentOS Stream, Rocky Linux
   - Development: Ubuntu, Debian, openSUSE

3. **Consider support requirements:**
   - Commercial support: RHEL, SLES
   - Community support: CentOS Stream, Rocky Linux, AlmaLinux, Debian, Ubuntu, openSUSE

### Resource Allocation

**Minimum Requirements:**
- 1 vCPU, 1GB RAM, 10GB disk (testing only)

**Recommended for Production:**
- 2+ vCPUs, 2GB+ RAM, 20GB+ disk

**Workload-Specific:**
```
Web Server:        2-4 vCPUs,  4GB RAM,  40GB disk
Database Server:   4-8 vCPUs, 16GB RAM, 100GB+ disk
Application Server: 4-8 vCPUs,  8GB RAM,  80GB disk
Container Host:    4-8 vCPUs, 16GB RAM,  80GB disk
Development:       2-4 vCPUs,  8GB RAM,  50GB disk
```

### Security Hardening

1. **Change default passwords immediately:**
   ```bash
   sudo passwd root  # Change from ChangeMe123!
   ```

2. **Configure proper SSH keys:**
   - Use dedicated key per environment
   - Rotate keys regularly (90-180 days)
   - Use Ed25519 keys when possible

3. **Enable additional security features:**
   - CIS benchmarks scanning
   - Intrusion detection (fail2ban, OSSEC)
   - Log forwarding to SIEM
   - Vulnerability scanning

4. **Regular updates:**
   - Monitor automatic update logs
   - Schedule manual updates for major versions
   - Test updates in staging first

### Operational Excellence

1. **Naming Conventions:**
   - Use descriptive, meaningful VM names
   - Include purpose and environment: `web-prod-01`, `db-dev-01`
   - Document naming scheme

2. **Inventory Management:**
   - Keep Ansible inventory up-to-date
   - Document VM purpose and owner
   - Track VM lifecycle

3. **Monitoring:**
   - Set up monitoring for all VMs
   - Configure alerting for critical issues
   - Monitor resource usage trends

4. **Backup Strategy:**
   - Regular VM backups or disk snapshots
   - Test restore procedures
   - Document backup retention policy

5. **Documentation:**
   - Document VM purpose and configuration
   - Maintain runbooks for common tasks
   - Keep network diagrams current

### Performance Optimization

1. **Disk I/O:**
   - Use virtio drivers (already configured)
   - Consider separate disk for databases
   - Use appropriate filesystem (xfs for RHEL, ext4 for Debian)

2. **Network:**
   - Use virtio network driver (already configured)
   - Consider SR-IOV for high-performance needs
   - Monitor network latency

3. **CPU:**
   - Right-size vCPU allocation
   - Avoid overcommitment on critical VMs
   - Use CPU pinning for performance-critical workloads

4. **Memory:**
   - Allocate sufficient RAM to avoid swapping
   - Monitor memory usage
   - Consider huge pages for databases

## References

- [CLAUDE.md](../CLAUDE.md) - Infrastructure guidelines
- [Cheatsheet](../cheatsheets/deploy-linux-vm.md) - Quick reference
- [Debian Cloud Images](https://cloud.debian.org/images/cloud/)
- [Ubuntu Cloud Images](https://cloud-images.ubuntu.com/)
- [CentOS Stream](https://www.centos.org/centos-stream/)
- [Rocky Linux](https://rockylinux.org/)
- [AlmaLinux](https://almalinux.org/)
- [openSUSE](https://www.opensuse.org/)
- [cloud-init Documentation](https://cloudinit.readthedocs.io/)
- [libvirt Documentation](https://libvirt.org/docs.html)

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