10.4 Virtual Machines Setup¶

Overview¶

This section covers the creation of two Linux virtual machines running Ubuntu 22.04 LTS. The VMs are configured with password authentication and will host Nginx web servers.

Random Password Generation¶

Terraform Configuration¶

resource "random_password" "example" {
  length  = 16
  special = true
  lower   = true
  upper   = true
  numeric = true
}

Password Requirements¶

Length: 16 characters
Complexity: Includes uppercase, lowercase, numbers, and special characters
Security: Randomly generated, meets Azure password requirements

Usage¶

The password is used as a fallback if no password is provided via variables:

admin_password = coalesce(var.password, random_password.example.result)

Logic: If var.password is empty, use the randomly generated password.

Virtual Machine Configuration¶

Terraform Configuration¶

resource "azurerm_linux_virtual_machine" "example" {
  count                 = 2
  name                  = "${var.virtual_machine_name}${count.index}"
  location              = azurerm_resource_group.example.location
  resource_group_name   = azurerm_resource_group.example.name
  network_interface_ids = [azurerm_network_interface.example[count.index].id]
  size                  = var.virtual_machine_size

  os_disk {
    name                 = "${var.disk_name}${count.index}"
    caching              = "ReadWrite"
    storage_account_type = var.redundancy_type
  }

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

  admin_username                  = var.username
  admin_password                  = coalesce(var.password, random_password.example.result)
  disable_password_authentication = false
}

Configuration Breakdown¶

Basic Properties¶

Property	Value	Description
count	2	Creates two VMs (VM 0 and VM 1)
name	`test-vm0`, `test-vm1`	Indexed naming
location	From resource group	Same region as other resources
resource_group_name	From resource group	Logical container
network_interface_ids	Array with one NIC	Connects VM to network
size	`Standard_B2s`	VM size/SKU

VM Size: Standard_B2s¶

Specifications: - vCPUs: 2 - RAM: 4 GB - Temp Storage: 8 GB - Max Data Disks: 4 - Max NICs: 2 - Cost: ~$30-40/month (varies by region)

Use Case: Development, testing, low-traffic web servers

Alternatives: - Standard_B1s: 1 vCPU, 1 GB RAM (cheaper, minimal workloads) - Standard_B2ms: 2 vCPU, 8 GB RAM (more memory) - Standard_D2s_v3: 2 vCPU, 8 GB RAM (production workloads)

OS Disk Configuration¶

os_disk {
  name                 = "${var.disk_name}${count.index}"
  caching              = "ReadWrite"
  storage_account_type = var.redundancy_type
}

Property	Value	Description
name	`test-disk0`, `test-disk1`	Disk identifier
caching	`ReadWrite`	Caches reads and writes
storage_account_type	`Standard_LRS`	Locally redundant storage

Storage Types¶

Type	Performance	Redundancy	Use Case	Cost
Standard_LRS	HDD	Local	Dev/Test	$
StandardSSD_LRS	SSD	Local	General purpose	$$
Premium_LRS	Premium SSD	Local	Production	$$$
Premium_ZRS	Premium SSD	Zone	High availability	$$$$

Caching Options¶

Option	Behavior	Use Case
None	No caching	Write-intensive workloads
ReadOnly	Cache reads	Read-heavy workloads
ReadWrite	Cache both	General purpose (default)

Operating System Image¶

Image Reference¶

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

Image Details¶

Publisher: Canonical (Ubuntu maintainer)
Offer: Ubuntu Server 22.04 LTS (Jammy Jellyfish)
SKU: 22.04 LTS Generation 2
Version: Latest available

Why Ubuntu 22.04 LTS?¶

LTS: Long-term support until 2027
Stability: Production-ready
Package Support: Extensive repository
Gen2: Better performance, UEFI boot

Finding Other Images¶

# List publishers
az vm image list-publishers --location eastus --output table

# List offers from Canonical
az vm image list-offers --publisher Canonical --location eastus --output table

# List SKUs
az vm image list-skus \
  --publisher Canonical \
  --offer 0001-com-ubuntu-server-jammy \
  --location eastus \
  --output table

# List versions
az vm image list \
  --publisher Canonical \
  --offer 0001-com-ubuntu-server-jammy \
  --sku 22_04-lts-gen2 \
  --location eastus \
  --all \
  --output table

Authentication Configuration¶

Password Authentication¶

admin_username                  = var.username
admin_password                  = coalesce(var.password, random_password.example.result)
disable_password_authentication = false

Property	Value	Description
admin_username	`azureadmin`	Admin account name
admin_password	Variable or random	Secure password
disable_password_authentication	`false`	Allows password login

Security Considerations¶

⚠️ Password Authentication: Enabled for simplicity, but consider SSH keys for production.

Better Approach for Production:

resource "azurerm_linux_virtual_machine" "example" {
  # ... other configuration ...

  admin_username                  = var.username
  disable_password_authentication = true

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

Variables¶

VM Configuration Variables¶

variable "username" {
  type        = string
  default     = "azureadmin"
  description = "The username for the local account that will be created on the new VM."
}

variable "password" {
  type        = string
  default     = ""
  description = "The password for the local account that will be created on the new VM."
}

variable "virtual_machine_name" {
  type        = string
  default     = "test-vm"
  description = "Name of the Virtual Machine."
}

variable "virtual_machine_size" {
  type        = string
  default     = "Standard_B2s"
  description = "Size or SKU of the Virtual Machine."
}

Storage Variables¶

variable "disk_name" {
  type        = string
  default     = "test-disk"
  description = "Name of the OS disk of the Virtual Machine."
}

variable "redundancy_type" {
  type        = string
  default     = "Standard_LRS"
  description = "Storage redundancy type of the OS disk."
}

VM Lifecycle¶

Creation Process¶

1. Terraform creates random password
2. Terraform creates NICs
3. Terraform creates VMs with NICs attached
4. Azure provisions VMs
5. VMs boot and become available
6. VM extensions install (next section)

Resource Dependencies¶

random_password.example
        ↓
azurerm_network_interface.example[0,1]
        ↓
azurerm_linux_virtual_machine.example[0,1]
        ↓
azurerm_virtual_machine_extension.example[0,1]

Azure CLI Verification¶

List VMs¶

az vm list \
  --resource-group <resource-group-name> \
  --output table

Show VM Details¶

az vm show \
  --resource-group <resource-group-name> \
  --name test-vm0 \
  --output json

Get VM Status¶

az vm get-instance-view \
  --resource-group <resource-group-name> \
  --name test-vm0 \
  --query instanceView.statuses \
  --output table

Get Private IP Address¶

az vm list-ip-addresses \
  --resource-group <resource-group-name> \
  --name test-vm0 \
  --output table

Retrieve Generated Password¶

# Using Terraform
terraform output vm_password

# Note: Output is marked as sensitive, use:
terraform output -raw vm_password

VM Management Commands¶

Start VM¶

az vm start \
  --resource-group <resource-group-name> \
  --name test-vm0

Stop VM (Deallocate)¶

az vm deallocate \
  --resource-group <resource-group-name> \
  --name test-vm0

Restart VM¶

az vm restart \
  --resource-group <resource-group-name> \
  --name test-vm0

Resize VM¶

# List available sizes
az vm list-sizes \
  --location eastus \
  --output table

# Resize VM
az vm resize \
  --resource-group <resource-group-name> \
  --name test-vm0 \
  --size Standard_B2ms

Advanced Configurations¶

Custom Data (Cloud-Init)¶

resource "azurerm_linux_virtual_machine" "example" {
  # ... other configuration ...

  custom_data = base64encode(<<-EOF
    #!/bin/bash
    apt-get update
    apt-get install -y nginx
    echo "Hello from $(hostname)" > /var/www/html/index.html
    systemctl restart nginx
  EOF
  )
}

Availability Set¶

For better availability without load balancer:

resource "azurerm_availability_set" "example" {
  name                = "test-avset"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
}

resource "azurerm_linux_virtual_machine" "example" {
  # ... other configuration ...
  availability_set_id = azurerm_availability_set.example.id
}

Managed Identity¶

For Azure service authentication:

resource "azurerm_linux_virtual_machine" "example" {
  # ... other configuration ...

  identity {
    type = "SystemAssigned"
  }
}

Cost Optimization¶

Development/Testing¶

Use B-series (burstable) VMs
Stop VMs when not in use (deallocate)
Use Standard_LRS storage

Production¶

Use Reserved Instances (1-3 year commitment)
Right-size VMs based on monitoring
Use Azure Hybrid Benefit if you have Windows licenses

Cost Calculation¶

VM Cost = (VM Size Cost + Storage Cost) × Hours Running
Example: Standard_B2s in East US
- VM: ~$0.0416/hour
- Storage (30GB Standard_LRS): ~$1.54/month
- Total: ~$32/month (if running 24/7)

Best Practices¶

Use SSH Keys: More secure than passwords for production
Enable Boot Diagnostics: Helps troubleshoot boot issues
Use Managed Disks: Simpler management, better reliability
Tag Resources: For cost tracking and organization
Regular Updates: Keep OS and packages updated
Monitoring: Enable Azure Monitor for VMs
Backup: Configure Azure Backup for production VMs

Next Steps¶

Proceed to 10.5-Load-Balancer-Setup.md to configure the load balancer that distributes traffic across these VMs.