Azure Virtual Machines

Deploy and manage Azure VMs, availability sets, scale sets, custom images, and managed disks. Covers VM creation, sizing, disk management, auto-scaling, and Terraform configurations for production environments.

When to Use

• You need full control over the operating system and runtime environment.
• Your application requires specific OS configurations or kernel modules.
• You are running legacy applications that cannot be containerized.
• You need GPU-accelerated compute for ML training or rendering.
• You need high-availability compute with availability zones or scale sets.

Prerequisites

# Install Azure CLI
curl -sL https://aka.ms/InstallAzureCLIDeb | sudo bash

# Login and set subscription
az login
az account set --subscription "my-subscription-id"

# Create resource group
az group create --name compute-rg --location eastus

# List available VM sizes in a region
az vm list-sizes --location eastus --output table

# List available VM images
az vm image list --output table
az vm image list --publisher Canonical --offer 0001-com-ubuntu-server-jammy --all --output table

VM Creation

Linux VM with SSH Key

az vm create \
  --resource-group compute-rg \
  --name myapp-vm \
  --image Ubuntu2204 \
  --size Standard_D4s_v5 \
  --admin-username azureuser \
  --generate-ssh-keys \
  --vnet-name myapp-vnet \
  --subnet app-subnet \
  --nsg "" \
  --public-ip-address "" \
  --os-disk-size-gb 64 \
  --os-disk-caching ReadWrite \
  --storage-sku Premium_LRS \
  --zone 1 \
  --assign-identity \
  --tags environment=prod team=platform app=myapp

# SSH into the VM (if public IP assigned)
ssh azureuser@$(az vm show -g compute-rg -n myapp-vm -d --query publicIps -o tsv)

Windows VM

az vm create \
  --resource-group compute-rg \
  --name myapp-win-vm \
  --image Win2022Datacenter \
  --size Standard_D4s_v5 \
  --admin-username azureadmin \
  --admin-password 'S3cur3P@ssw0rd!' \
  --vnet-name myapp-vnet \
  --subnet app-subnet \
  --public-ip-address "" \
  --os-disk-size-gb 128 \
  --storage-sku Premium_LRS \
  --zone 1

VM with Cloud-Init

# cloud-init.yaml
# #cloud-config
# package_update: true
# packages:
#   - nginx
#   - docker.io
# runcmd:
#   - systemctl enable nginx
#   - systemctl start nginx
#   - usermod -aG docker azureuser

az vm create \
  --resource-group compute-rg \
  --name web-vm \
  --image Ubuntu2204 \
  --size Standard_B2s \
  --admin-username azureuser \
  --generate-ssh-keys \
  --custom-data cloud-init.yaml \
  --tags role=web

VM Size Guide

Family	Example Sizes	Use Case
B-series	Standard_B1s, Standard_B2s	Dev/test, low-traffic web servers
D-series	Standard_D4s_v5, Standard_D8s_v5	General purpose, most production workloads
E-series	Standard_E4s_v5, Standard_E16s_v5	Memory-intensive (databases, caching)
F-series	Standard_F4s_v2, Standard_F16s_v2	CPU-intensive (batch processing, analytics)
L-series	Standard_L8s_v3, Standard_L32s_v3	Storage-optimized (big data, SQL)
N-series	Standard_NC6s_v3, Standard_NC24ads_A100_v4	GPU workloads (ML training, rendering)
M-series	Standard_M128s	SAP HANA, large in-memory workloads

# Find VM sizes with specific capabilities
az vm list-sizes --location eastus \
  --query "[?numberOfCores >= \`4\` && memoryInMb >= \`16000\`]" \
  --output table

# Check VM size availability in a zone
az vm list-skus --location eastus \
  --size Standard_D4s_v5 \
  --output table

Managed Disks

# Add a data disk to existing VM
az vm disk attach \
  --resource-group compute-rg \
  --vm-name myapp-vm \
  --name myapp-data-disk \
  --size-gb 256 \
  --sku Premium_LRS \
  --new \
  --lun 0

# Create a standalone managed disk
az disk create \
  --resource-group compute-rg \
  --name shared-data-disk \
  --size-gb 512 \
  --sku Premium_LRS \
  --zone 1

# Resize a disk (VM must be deallocated)
az vm deallocate --resource-group compute-rg --name myapp-vm
az disk update \
  --resource-group compute-rg \
  --name myapp-data-disk \
  --size-gb 512
az vm start --resource-group compute-rg --name myapp-vm

# Snapshot a disk for backup
az snapshot create \
  --resource-group compute-rg \
  --name myapp-disk-snapshot \
  --source myapp-data-disk

# Create disk from snapshot
az disk create \
  --resource-group compute-rg \
  --name myapp-disk-from-snap \
  --source myapp-disk-snapshot \
  --sku Premium_LRS

# List disks attached to a VM
az vm show \
  --resource-group compute-rg \
  --name myapp-vm \
  --query "storageProfile.dataDisks" \
  --output table

Custom Images

# Generalize the VM (run inside the VM first)
# sudo waagent -deprovision+user -force

# Deallocate and generalize
az vm deallocate --resource-group compute-rg --name myapp-vm
az vm generalize --resource-group compute-rg --name myapp-vm

# Create image from VM
az image create \
  --resource-group compute-rg \
  --name myapp-golden-image \
  --source myapp-vm \
  --os-type Linux

# Create VM from custom image
az vm create \
  --resource-group compute-rg \
  --name myapp-from-image \
  --image myapp-golden-image \
  --size Standard_D4s_v5 \
  --admin-username azureuser \
  --generate-ssh-keys

# Use Azure Compute Gallery for shared images
az sig create \
  --resource-group compute-rg \
  --gallery-name myAppGallery

az sig image-definition create \
  --resource-group compute-rg \
  --gallery-name myAppGallery \
  --gallery-image-definition myapp-image \
  --publisher myorg \
  --offer myapp \
  --sku 1.0 \
  --os-type Linux \
  --os-state Generalized

az sig image-version create \
  --resource-group compute-rg \
  --gallery-name myAppGallery \
  --gallery-image-definition myapp-image \
  --gallery-image-version 1.0.0 \
  --managed-image myapp-golden-image \
  --target-regions eastus westus \
  --replica-count 2

Availability Sets and Zones

# Create availability set
az vm availability-set create \
  --resource-group compute-rg \
  --name myapp-avset \
  --platform-fault-domain-count 3 \
  --platform-update-domain-count 5

# Create VM in availability set
az vm create \
  --resource-group compute-rg \
  --name myapp-vm-1 \
  --image Ubuntu2204 \
  --size Standard_D4s_v5 \
  --availability-set myapp-avset \
  --admin-username azureuser \
  --generate-ssh-keys

# Create VMs across availability zones
for zone in 1 2 3; do
  az vm create \
    --resource-group compute-rg \
    --name "myapp-vm-zone${zone}" \
    --image Ubuntu2204 \
    --size Standard_D4s_v5 \
    --zone "$zone" \
    --admin-username azureuser \
    --generate-ssh-keys \
    --no-wait
done

Virtual Machine Scale Sets

# Create VMSS with autoscaling
az vmss create \
  --resource-group compute-rg \
  --name myapp-vmss \
  --image Ubuntu2204 \
  --vm-sku Standard_D4s_v5 \
  --instance-count 2 \
  --admin-username azureuser \
  --generate-ssh-keys \
  --vnet-name myapp-vnet \
  --subnet app-subnet \
  --upgrade-policy-mode Rolling \
  --health-probe "/" \
  --load-balancer myapp-lb \
  --zones 1 2 3 \
  --custom-data cloud-init.yaml \
  --tags environment=prod

# Configure autoscale rules
az monitor autoscale create \
  --resource-group compute-rg \
  --resource myapp-vmss \
  --resource-type Microsoft.Compute/virtualMachineScaleSets \
  --name myapp-autoscale \
  --min-count 2 \
  --max-count 20 \
  --count 3

# Scale out when CPU > 70%
az monitor autoscale rule create \
  --resource-group compute-rg \
  --autoscale-name myapp-autoscale \
  --condition "Percentage CPU > 70 avg 5m" \
  --scale out 2

# Scale in when CPU < 30%
az monitor autoscale rule create \
  --resource-group compute-rg \
  --autoscale-name myapp-autoscale \
  --condition "Percentage CPU < 30 avg 10m" \
  --scale in 1

# Manual scale
az vmss scale \
  --resource-group compute-rg \
  --name myapp-vmss \
  --new-capacity 5

# Update VMSS image
az vmss update \
  --resource-group compute-rg \
  --name myapp-vmss \
  --set virtualMachineProfile.storageProfile.imageReference.version=latest

# Rolling upgrade of instances
az vmss rolling-upgrade start \
  --resource-group compute-rg \
  --name myapp-vmss

# List VMSS instances
az vmss list-instances \
  --resource-group compute-rg \
  --name myapp-vmss \
  --output table

VM Management Operations

# Start / Stop / Restart / Deallocate
az vm start --resource-group compute-rg --name myapp-vm
az vm stop --resource-group compute-rg --name myapp-vm
az vm restart --resource-group compute-rg --name myapp-vm
az vm deallocate --resource-group compute-rg --name myapp-vm

# Run command on a VM
az vm run-command invoke \
  --resource-group compute-rg \
  --name myapp-vm \
  --command-id RunShellScript \
  --scripts "df -h && free -m && uptime"

# Enable boot diagnostics
az vm boot-diagnostics enable \
  --resource-group compute-rg \
  --name myapp-vm

# Get boot diagnostics log
az vm boot-diagnostics get-boot-log \
  --resource-group compute-rg \
  --name myapp-vm

# Enable Azure Backup
az backup protection enable-for-vm \
  --resource-group compute-rg \
  --vault-name myapp-vault \
  --vm myapp-vm \
  --policy-name DefaultPolicy

# Resize a VM
az vm resize \
  --resource-group compute-rg \
  --name myapp-vm \
  --size Standard_D8s_v5

Terraform Configuration

resource "azurerm_linux_virtual_machine" "main" {
  name                  = "myapp-vm"
  resource_group_name   = azurerm_resource_group.main.name
  location              = azurerm_resource_group.main.location
  size                  = "Standard_D4s_v5"
  admin_username        = "azureuser"
  zone                  = "1"
  network_interface_ids = [azurerm_network_interface.main.id]

  admin_ssh_key {
    username   = "azureuser"
    public_key = file("~/.ssh/id_rsa.pub")
  }

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Premium_LRS"
    disk_size_gb         = 64
  }

  source_image_reference {
    publisher = "Canonical"
    offer     = "0001-com-ubuntu-server-jammy"
    sku       = "22_04-lts-gen2"
    version   = "latest"
  }

  identity {
    type = "SystemAssigned"
  }

  tags = var.tags
}

resource "azurerm_managed_disk" "data" {
  name                 = "myapp-data-disk"
  resource_group_name  = azurerm_resource_group.main.name
  location             = azurerm_resource_group.main.location
  storage_account_type = "Premium_LRS"
  create_option        = "Empty"
  disk_size_gb         = 256
  zone                 = "1"
  tags                 = var.tags
}

resource "azurerm_virtual_machine_data_disk_attachment" "data" {
  managed_disk_id    = azurerm_managed_disk.data.id
  virtual_machine_id = azurerm_linux_virtual_machine.main.id
  lun                = 0
  caching            = "ReadOnly"
}

resource "azurerm_linux_virtual_machine_scale_set" "main" {
  name                = "myapp-vmss"
  resource_group_name = azurerm_resource_group.main.name
  location            = azurerm_resource_group.main.location
  sku                 = "Standard_D4s_v5"
  instances           = 3
  admin_username      = "azureuser"
  zones               = [1, 2, 3]

  admin_ssh_key {
    username   = "azureuser"
    public_key = file("~/.ssh/id_rsa.pub")
  }

  source_image_reference {
    publisher = "Canonical"
    offer     = "0001-com-ubuntu-server-jammy"
    sku       = "22_04-lts-gen2"
    version   = "latest"
  }

  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Premium_LRS"
  }

  network_interface {
    name    = "vmss-nic"
    primary = true

    ip_configuration {
      name      = "internal"
      primary   = true
      subnet_id = azurerm_subnet.app.id
    }
  }

  automatic_os_upgrade_policy {
    disable_automatic_rollback  = false
    enable_automatic_os_upgrade = true
  }

  rolling_upgrade_policy {
    max_batch_instance_percent              = 20
    max_unhealthy_instance_percent          = 20
    max_unhealthy_upgraded_instance_percent = 5
    pause_time_between_batches              = "PT0S"
  }

  tags = var.tags
}

Troubleshooting

Symptom	Cause	Fix
VM fails to start	Quota exceeded in region	Check quota with az vm list-usage --location eastus; request increase
SSH connection refused	NSG blocking port 22 or VM not running	Check NSG rules and VM power state; use Azure Bastion for private VMs
VM disk full	OS disk too small or logs not rotated	Resize disk after deallocating; configure log rotation
VM performance is slow	Wrong VM size or disk throttling	Check metrics with az monitor metrics list; upgrade size or disk tier
Scale set not scaling out	Autoscale rule threshold not met	Review autoscale settings; verify metric thresholds match workload
Custom image VM boot fails	Image not properly generalized	Re-run waagent -deprovision before capturing; check boot diagnostics
VMSS rolling upgrade stuck	Health probe failing on new instances	Fix application health endpoint; check az vmss rolling-upgrade get-latest
Spot VM evicted unexpectedly	Azure reclaimed capacity	Use eviction policy Deallocate and set up eviction notifications

Related Skills

• azure-networking -- VNet and NSG configuration for VM connectivity.
• azure-aks -- Container alternative when VMs are not required.
• arm-templates -- Bicep-based VM deployment templates.
• terraform-azure -- Terraform-based VM and VMSS provisioning.