Chapter 09 — Azure Compute Services

What is Compute?

Compute refers to the processing power needed to run applications — CPUs, memory (RAM), and the environments that run your code.

Azure offers several compute options, each suited for different workload types:

Azure Compute Services:
  ├── Virtual Machines (VMs)
  ├── Azure App Service
  ├── Azure Functions (Serverless)
  ├── Azure Container Instances (ACI)
  ├── Azure Kubernetes Service (AKS)
  └── Azure Virtual Desktop

1. Azure Virtual Machines (VMs)

What Are VMs?

An Azure Virtual Machine is a software-based computer that runs on Microsoft's physical servers. It behaves exactly like a physical computer — you get a CPU, RAM, storage, and network — but it's hosted in the cloud.

VMs are the foundation of IaaS (Infrastructure as a Service).

Key Characteristics

VM Series (Types)

When to Use VMs

• Migrating on-premises workloads to cloud ("lift and shift")

• Running legacy software that needs full OS control

• Custom OS configurations and specialized software

• Testing environments needing specific OS setups

VM Scale Sets

Virtual Machine Scale Sets automatically increase or decrease the number of VMs based on demand.

Normal traffic:   3 VMs running
Peak traffic:     Auto-scale to 20 VMs
Traffic drops:    Auto-scale back to 3 VMs

2. Azure App Service

What Is It?

Azure App Service is a fully managed PaaS platform for hosting web applications, REST APIs, and mobile backends. You deploy your code — Azure handles the infrastructure, OS, and runtime.

Key Characteristics

App Service Plans

An App Service Plan defines the underlying compute resources (CPU, RAM) for your app:

When to Use App Service

• Hosting web applications and APIs

• When you want to focus on code, not servers

• Apps that need auto-scaling and SSL out of the box

• Rapid deployment from GitHub or DevOps pipelines

3. Azure Functions (Serverless Compute)

What Is It?

Azure Functions is a serverless compute service where you write small pieces of code (functions) that run in response to events — without managing any servers.

You only pay when your code runs — not for idle time.

How It Works

Trigger (Event Occurs)  →  Azure Functions runs your code  →  Done
Examples of triggers:
  - HTTP request received
  - File uploaded to blob storage
  - Message added to a queue
  - Timer fires at scheduled time
  - Database record changes

Key Characteristics

Pricing Plans

When to Use Azure Functions

• Event-driven workloads (respond to file uploads, HTTP calls, messages)

• Scheduled tasks (run a report every night at midnight)

• Microservices architecture

• Low-cost, low-traffic scenarios where idle time shouldn't cost money

4. Azure Container Instances (ACI)

What Are Containers?

A container packages your application code + all its dependencies into a single portable unit. Containers are lightweight and run consistently across environments.

Container vs. Virtual Machine:
  VM:        Full OS + App (GBs in size, minutes to start)
  Container: Just App + Dependencies (MBs in size, seconds to start)

What Is ACI?

Azure Container Instances (ACI) is the simplest way to run containers in Azure — without managing VMs or clusters. You just provide a container image, and Azure runs it.

When to Use ACI

• Simple containerized applications or microservices

• Batch jobs and data processing tasks

• Testing containerized applications quickly

• Workloads that don't need full Kubernetes orchestration

5. Azure Kubernetes Service (AKS)

What Is Kubernetes?

Kubernetes (K8s) is an open-source system for automating the deployment, scaling, and management of containerized applications across a cluster of machines.

What Is AKS?

Azure Kubernetes Service (AKS) is a managed Kubernetes service — Azure handles the complexity of setting up and operating a Kubernetes cluster.

AKS Cluster
├── Control Plane (managed by Azure — free)
│     ├── API Server
│     ├── Scheduler
│     └── Controller Manager
└── Node Pool (worker nodes — you pay for these)
      ├── Node 1 (VM) → Pods (your containers)
      ├── Node 2 (VM) → Pods
      └── Node 3 (VM) → Pods

Key Characteristics

When to Use AKS

• Running many containerized microservices

• Applications needing sophisticated scheduling and scaling

• Large-scale production container workloads

• Organizations already using Docker and Kubernetes

6. Azure Virtual Desktop

What Is It?

Azure Virtual Desktop (AVD) is a desktop-as-a-service — it delivers Windows desktops and applications to any device over the internet.

Users connect through a browser or Remote Desktop client and see a full Windows desktop running in the cloud.

Compute Services Comparison

Quick Recap

VM            → Full control, full OS — like a cloud PC
App Service   → Managed web hosting — just deploy code
Functions     → Serverless — pay per execution, event-driven
ACI           → Run containers without clusters
AKS           → Managed Kubernetes for container orchestration
Virtual Desktop → Cloud-hosted Windows for remote workers

Official References

• Azure Virtual Machines

• Azure App Service

• Azure Functions

• Azure Container Instances

• Azure Kubernetes Service

• Azure Virtual Desktop

Next Chapter → Chapter 10: Azure Networking Services