Chapter 1: Introduction to Azure

What is Microsoft Azure?

Microsoft Azure is a cloud computing platform offering 200+ services (from raw virtual machines to managed AI models) hosted across Microsoft's global network of data centres. You pay only for what you use (consumption-based billing), and you can scale resources up or down in minutes without buying physical hardware.

Cloud Computing Models

┌─────────────────────────────────────────────────────────────┐
│                   Cloud Service Models                      │
├──────────────┬──────────────────────┬───────────────────────┤
│     IaaS     │        PaaS          │         SaaS          │
│  (You manage │  (Platform manages   │  (Everything managed) │
│   most)      │   the runtime)       │                       │
├──────────────┼──────────────────────┼───────────────────────┤
│ Azure VMs    │ App Service          │ Microsoft 365         │
│ Disks        │ Azure SQL Database   │ Dynamics 365          │
│ VNets        │ Azure Functions      │ Azure DevOps (SaaS)   │
│              │ AKS (managed K8s)    │                       │
└──────────────┴──────────────────────┴───────────────────────┘

Deployment Models

• Public Cloud: Resources run on Microsoft's shared infrastructure. Most common.
• Private Cloud: Dedicated hardware for one organisation (Azure Dedicated Host).
• Hybrid Cloud: On-premises + cloud connected via Azure Arc, VPN, or ExpressRoute.
• Multi-Cloud: Azure workloads alongside AWS or GCP (increasingly common).

Why Azure?

1. Enterprise integration: Deep ties to Active Directory, Microsoft 365, and Windows Server make migration easier for existing Microsoft shops
2. Compliance portfolio: 100+ compliance certifications (ISO, SOC, HIPAA, FedRAMP, GDPR)
3. Hybrid story: Azure Arc, Azure Stack, and ExpressRoute make hybrid deployments first-class citizens
4. Developer ecosystem: Native GitHub integration, Visual Studio tooling, and strong .NET support
5. AI & ML services: Azure OpenAI, Cognitive Services, and Azure ML are production-grade
6. Global reach: 60+ regions worldwide, more than any other cloud provider

Azure Global Infrastructure

Regions

A region is a geographic area containing one or more data centres. Every resource you create is deployed to a region.

Key Regions (partial list):
├── Americas
│   ├── East US (Virginia)        ← Most services launch here first
│   ├── East US 2 (Virginia)
│   ├── West US 2 (Washington)
│   ├── West US 3 (Arizona)
│   ├── Central US (Iowa)
│   └── Brazil South (São Paulo)
├── Europe
│   ├── West Europe (Netherlands)
│   ├── North Europe (Ireland)
│   ├── UK South (London)
│   └── Germany West Central (Frankfurt)
└── Asia Pacific
    ├── East Asia (Hong Kong)
    ├── Southeast Asia (Singapore)
    ├── Australia East (Sydney)
    └── Japan East (Tokyo)

How to choose a region:

1. Proximity to users: lower latency
2. Compliance requirements: data sovereignty laws (e.g., EU data must stay in EU)
3. Service availability: not all services are in all regions
4. Pricing: prices vary by region (East US is typically cheapest)
5. Paired regions: Azure pairs regions for disaster recovery (e.g., East US and West US)

Availability Zones

Within a region, Availability Zones (AZs) are physically separate data centres (different power, cooling, and networking) that protect against data centre failures.

Region: East US
├── Availability Zone 1  (Data centre A)
├── Availability Zone 2  (Data centre B)
└── Availability Zone 3  (Data centre C)

• Deploy VMs across zones to survive a full data centre outage
• Zone-redundant services (e.g., Azure SQL, Storage) replicate automatically across zones
• SLA increases: single VM = 99.9%, two VMs across zones = 99.99%

Availability Sets

For VMs in the same region but before AZ support existed, Availability Sets distribute VMs across:

• Fault Domains (FD): separate physical racks (power + network)
• Update Domains (UD): groups rebooted separately during planned maintenance

Prefer Availability Zones over Availability Sets for new workloads.

Azure's Organisational Hierarchy

Azure Account (Microsoft account / Entra ID tenant)
└── Management Groups  (optional hierarchy for policies)
    └── Subscriptions  (billing + access boundary)
        └── Resource Groups  (logical container)
            └── Resources  (VMs, databases, storage...)

Subscriptions

A subscription is the billing and access boundary. One account can have many subscriptions.

Common patterns:

• prod-subscription / dev-subscription / staging-subscription
• Separate subscriptions per team or business unit
• Separate subscriptions to enforce cost limits (budgets per subscription)

Resource Groups

A resource group is a logical container for related resources. They share the same lifecycle: when you delete a resource group, everything inside is deleted too.

Best practices:

• Group resources by application and environment: myapp-prod-rg, myapp-dev-rg
• All resources in a group should share the same region (though cross-region is allowed)
• Use consistent naming conventions: {project}-{env}-{region}-rg

# Create a resource group
az group create \
  --name myapp-prod-rg \
  --location eastus \
  --tags environment=prod project=myapp

Management Groups

For large organisations with many subscriptions, Management Groups let you apply Azure Policy and RBAC across multiple subscriptions at once.

Root Management Group
├── Corp MG
│   ├── IT Subscription
│   └── Finance Subscription
└── Platform MG
    ├── Connectivity Subscription
    └── Identity Subscription

Azure Services Landscape

Azure groups its 200+ services into categories:

Core Azure Concepts

Tags

Tags are key-value metadata you apply to resources for cost tracking, automation, and organisation.

# Tag a resource group
az group update \
  --name myapp-prod-rg \
  --set tags.environment=prod tags.owner=teamname tags.costcenter=12345

Azure Policy

Policies enforce rules across your Azure environment, e.g., "all resources must have a costcenter tag", "VMs must use approved SKUs only", "resources can only be created in approved regions".

Locks

Prevent accidental deletion or modification:

# Prevent deletion of a resource group
az lock create \
  --name DoNotDelete \
  --resource-group myapp-prod-rg \
  --lock-type CanNotDelete

# Prevent any changes (read-only)
az lock create \
  --name ReadOnly \
  --resource-group myapp-prod-rg \
  --lock-type ReadOnly

Pricing & Cost Management

Azure uses a pay-as-you-go model with several saving options:

Always use the Azure Pricing Calculator before committing to an architecture.

Azure vs Other Clouds

Next Steps

Continue to 02-getting-started.md to create your Azure account, set up the CLI, and deploy your first resource.