Serverless vs PaaS vs IaaS decision in Azure - Visual Side-by-Side Comparison

Process Flow - Serverless vs PaaS vs IaaS decision

Start: Need to deploy app

↓

Choose deployment model

↓

Serverless

↓

No infra

↓

management

↓

Pay per

↓

use

↓

Auto scale

↓

Less ops

↓

Deploy and run app

This flow shows how you start with an app deployment need, choose between Serverless, PaaS, or IaaS, each with different levels of infrastructure management and scaling.

Execution Sample

Azure

Decision: If app needs minimal management -> Serverless
Else if app needs managed platform -> PaaS
Else -> IaaS

This simple decision helps pick the right Azure service model based on management and control needs.

Process Table

Step	Decision Point	Condition	Chosen Model	Reason
1	App needs minimal infra management?	Yes	Serverless	No infra to manage, pay per use
2	App needs managed platform services?	Yes	PaaS	Managed services, less setup than IaaS
3	Else	No	IaaS	Full control over infrastructure
4	Scale needs	Auto scale needed?	Serverless	Built-in auto scaling
5	Scale needs	Manual or custom scale?	IaaS	User controls scaling
6	Ops effort	Want less ops?	Serverless or PaaS	Less operational overhead
7	Ops effort	Need full control?	IaaS	More operational responsibility
8	End	Decision complete	Model chosen	Ready to deploy app

💡 Decision ends when deployment model matches app needs for management, scaling, and control.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
App Management Need	Unknown	Minimal	Managed platform	Full control	Determined
Chosen Model	None	Serverless	PaaS	IaaS	Set
Scaling Type	Unknown	Auto	Auto or manual	Manual	Set
Ops Effort	Unknown	Low	Low	High	Set

Key Moments - 3 Insights

Why choose Serverless if I want full control over infrastructure?

Serverless is for minimal infrastructure management (see execution_table step 1). For full control, IaaS is better (step 3).

Can PaaS auto scale like Serverless?

PaaS can scale but usually requires some configuration (see execution_table step 4 and 5). Serverless auto scales automatically.

Does choosing IaaS mean more operational work?

Yes, IaaS requires managing servers and scaling manually (see execution_table step 7). Serverless and PaaS reduce ops effort.

Visual Quiz - 3 Questions

Look at the execution_table at step 1, what model is chosen if the app needs minimal infrastructure management?

A PaaS

B IaaS

C Serverless

D None

💡 Hint

Check execution_table row with Step 1 and Condition 'Yes'

At which step does the decision choose IaaS?

A Step 3

B Step 2

C Step 5

D Step 7

💡 Hint

Look for 'Else' condition in execution_table

If the app requires auto scaling with no ops effort, which models fit best?

A IaaS only

B Serverless or PaaS

C Serverless only

D PaaS or IaaS

💡 Hint

See execution_table steps 4 and 6 about scaling and ops effort

Concept Snapshot

Serverless: No infra management, pay per use, auto scale.
PaaS: Managed platform, less setup, some scaling.
IaaS: Full infra control, manual setup and scaling.
Choose based on control, ops effort, and scaling needs.

Full Transcript

This visual execution shows how to decide between Serverless, PaaS, and IaaS in Azure. Start by checking if your app needs minimal infrastructure management. If yes, Serverless is best for no infra management and pay per use. If you want managed platform services but not full control, choose PaaS. Otherwise, pick IaaS for full control but more operational work. Scaling is automatic in Serverless, configurable in PaaS, and manual in IaaS. This helps you pick the right model based on your app's needs.

Practice

1. Which Azure service model lets you run your code without worrying about managing servers and charges you only when your code runs?

easy

A. Serverless

B. PaaS

C. IaaS

D. On-premises servers

Solution

1. Step 1: Understand Serverless model

   Serverless runs your code without managing servers and charges based on usage.

2. Step 2: Compare with PaaS and IaaS

   PaaS provides a platform but you still deploy apps; IaaS requires managing virtual machines.

3. Final Answer:

   Serverless -> Option A

4. Quick Check:

   Serverless = code runs without server management [OK]

Hint: Serverless = no server management, pay per execution [OK]

Common Mistakes:

• Confusing PaaS with Serverless
• Thinking IaaS is serverless
• Assuming on-premises is cloud

2. Which Azure service model requires you to manage virtual machines and network settings yourself?

easy

A. Serverless

B. SaaS

C. PaaS

D. IaaS

Solution

1. Step 1: Identify IaaS responsibilities

   IaaS gives full control over virtual machines and network settings, so you manage them.

2. Step 2: Contrast with other models

   Serverless and PaaS abstract server management; SaaS is software delivered fully managed.

3. Final Answer:

   IaaS -> Option D

4. Quick Check:

   IaaS = manage VMs and network [OK]

Hint: IaaS means managing your own virtual machines [OK]

Common Mistakes:

• Mixing PaaS with IaaS management level
• Thinking Serverless requires VM management
• Confusing SaaS with IaaS

3. You want to deploy a web app quickly without managing servers but need some control over the environment. Which Azure model fits best?

medium

A. Serverless

B. PaaS

C. IaaS

D. On-premises

Solution

1. Step 1: Analyze deployment needs

   Quick deployment without server management suggests Serverless or PaaS.

2. Step 2: Consider control over environment

   Serverless offers less control; PaaS provides a ready platform with some environment control.

3. Final Answer:

   PaaS -> Option B

4. Quick Check:

   PaaS = quick deploy + some control [OK]

Hint: PaaS balances ease and control for app deployment [OK]

Common Mistakes:

• Choosing Serverless when environment control is needed
• Picking IaaS for quick deployment
• Confusing on-premises with cloud models

4. A developer deployed an app on Azure IaaS but forgot to configure the network security group. What is the likely issue?

medium

A. App is exposed to the internet without protection

B. App will not run because code is missing

C. Azure automatically secures the app by default

D. App will run serverless without VMs

Solution

1. Step 1: Understand IaaS network responsibility

   In IaaS, you must configure network security groups to protect VMs and apps.

2. Step 2: Consequence of missing security group

   Without it, the app is exposed to the internet without firewall protection.

3. Final Answer:

   App is exposed to the internet without protection -> Option A

4. Quick Check:

   IaaS needs manual network security setup [OK]

Hint: IaaS needs manual network security setup [OK]

Common Mistakes:

• Assuming Azure auto-secures IaaS apps
• Thinking app won't run without code
• Confusing serverless with IaaS

5. Your company needs to run a batch job that runs only a few minutes every day, with minimal management and cost. Which Azure model should you choose?

hard

A. IaaS with dedicated VMs running 24/7

B. PaaS with always-on app service

C. Serverless functions triggered by schedule

D. On-premises servers scheduled manually

Solution

1. Step 1: Analyze job characteristics

   The batch job runs briefly daily, so paying for always-on resources wastes money.

2. Step 2: Match model to cost and management needs

   Serverless functions run only when triggered, minimizing cost and management.

3. Step 3: Eliminate other options

   IaaS and PaaS keep resources running continuously, increasing cost; on-premises adds manual overhead.

4. Final Answer:

   Serverless functions triggered by schedule -> Option C

5. Quick Check:

   Short, infrequent jobs = Serverless [OK]

Hint: Use serverless for short, infrequent tasks to save cost [OK]

Common Mistakes:

• Choosing always-on VMs for short jobs
• Picking PaaS without considering cost
• Ignoring serverless scheduling options