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Real use cases + complete FAQ

Summary: the cloud is not a theory — it is what allows Netflix to serve 250 million subscribers without owning a single server, and a three-person startup to launch a worldwide product in one week. This final lesson presents five documented use cases, including deliberate repatriations, answers the 14 frequent questions, and guides you to your next step.

1. Use case 1 — Netflix, the historical reference​

The two most useful lessons: first, a real cloud migration takes years and involves rethinking the architecture, not moving machines. Second, even the cloud champion repatriated what needed to be — the video traffic, where egress would have cost a fortune, goes through infrastructure Netflix owns.

2. Use case 2 — Spotify and Google Cloud​

What this case illustrates: the choice of provider can be determined by a single decisive service. Spotify did not choose Google Cloud for its virtual machines — it chose it for BigQuery. It is a very common and perfectly rational decision motive.

3. Use case 3 — The French public sector​

Why this case concerns you: if you work in or aim for a position in the public sector, healthcare, banking or insurance in Europe, these constraints will shape your technical choices. Knowing what SecNumCloud is and why the provider's nationality matters is a real differentiating skill.

4. Use case 4 — The worldwide startup in one week​

5. Use case 5 — The deliberate repatriation​

This case is important for balance: the cloud is not always the right answer.

The lesson to remember: the right professional reflex is neither "everything to the cloud" nor "the cloud costs too much", but "what is my load profile, and which option serves it best?". An elastic, unpredictable load calls for the cloud. A load that is stable over five years deserves at least an honest comparative calculation.

6. The 14 most frequent questions​

1. Which provider to start learning with?

AWS if you have no constraint: it is the most in demand on the job market, the documentation and tutorials are the most abundant, and the skills are the most valued.

Azure if your current or targeted company is Microsoft-equipped.

Google Cloud if you are heading towards data, AI or Kubernetes.

The most important thing: the concepts are transferable. Learn one seriously rather than three superficially. Going from AWS to Azure takes a few weeks, not a whole new training.

2. How long to become operational on the cloud?

At a regular pace:

  • Understanding the concepts (this course): a few hours.
  • Knowing how to deploy a simple application: two to four weeks of practice.
  • Fundamental certification (Cloud Practitioner, AZ-900): four to eight weeks.
  • Associate level (Solutions Architect Associate): three to six months.
  • Real autonomy in production: six to twelve months, practising on real projects.

The limiting factor is always practice, never reading. Create an account and deploy something.

3. Can you learn the cloud for free?

Yes, largely. The three providers offer substantial free tiers, and the European players are very affordable.

What you can do without paying: deploy a web application, a test database, serverless functions, object storage, learn identities and virtual networking.

Indispensable precaution: configure a budget alert at 5 euros as soon as the account is created, and delete your resources after each session. Many learners discover an unexpected bill.

4. Will the cloud eliminate system administrator jobs?

No — the job transforms. What disappears: changing disks, cabling racks, updating firmwares.

What appears and pays better: automation (Terraform, Ansible), security and identity management, virtual networking, observability, Kubernetes, cost control.

Field observation: administrators who learned the cloud and automation saw their market value increase clearly. Those who refused this evolution saw their opportunities shrink.

5. Which cloud certification for a first job?

For a career change: start with a fundamental certification — AWS Cloud Practitioner, Azure Fundamentals (AZ-900) or Google Cloud Digital Leader. About 100 dollars, accessible in a few weeks.

For a technical position: aim for the associate level — AWS Solutions Architect Associate is the most recognized on the market, AZ-104 for Azure.

Honest warning: a certification opens doors but does not replace practice. In an interview, a personal project deployed and explained often weighs more than a badge. Do both.

6. How to avoid an unexpected bill?

Five measures, in order of importance:

  1. Budget alert as soon as the account is created. Non-negotiable.
  2. Delete what you create at the end of each learning session.
  3. Never commit an access key to Git — it is the classic cause of five-figure bills, via cryptocurrency mining.
  4. Enable two-factor authentication on your root account.
  5. Check the quotas before launching a large processing job.
7. Is the cloud environmentally friendly?

A nuanced and honest answer.

Favourable arguments: the hyperscalers' datacenters have an energy efficiency well above corporate server rooms. Pooling greatly increases the hardware utilization rate, hence reduces waste. The big three invest massively in renewable energy.

Unfavourable arguments: the cloud makes consumption so easy that it increases overall — that is the rebound effect. The manufacturing footprint of the hardware remains important. The growth of AI workloads strongly raises the total consumption.

Reasonable position: per unit of compute, the cloud is more efficient. But the rebound effect can cancel that gain. Choosing a region with low-carbon electricity (France, Sweden) has a real and measurable impact.

8. Do you need to know Linux to do cloud?

Strongly recommended, without being an absolute prerequisite. The vast majority of cloud machines run Linux, containers are Linux-based, and so are CI runners.

The useful minimum: navigating the file tree, reading logs, managing file permissions, using SSH, understanding processes and services.

Our Linux discovery course covers exactly these basics.

9. Cloud and DevOps, what is the relationship?

The cloud is the infrastructure; DevOps is the culture and the practices that exploit it effectively.

The cloud makes DevOps much more accessible: without an API to create a machine in 40 seconds, infrastructure as code and continuous deployment would remain very difficult.

But they are independent: you can do cloud without DevOps (manually deploying virtual machines with the mouse), and DevOps without cloud (automated pipelines on owned hardware).

10. How to migrate an existing application to the cloud?

There are five strategies, classically called the 5 Rs:

  1. Rehost (lift and shift) — move as-is. Fast, but no savings, often an extra cost.
  2. Replatform — move while adopting a few managed services, for example a managed database. Generally the best compromise.
  3. Refactor — rewrite to fully exploit the cloud. Expensive, maximum benefit.
  4. Retire — take advantage of the migration to remove what is no longer used. Often 10 to 20% of a fleet's applications.
  5. Retain — do not migrate what has no reason to be.

Practical advice: start with retire — the inventory almost always reveals applications nobody uses anymore.

11. What are the salaries in the cloud?

Orders of magnitude, highly variable by region, company size and sector:

  • Beginner with a fundamental certification: between 35,000 and 45,000 euros gross per year.
  • Two to four years of experience: between 45,000 and 60,000 euros.
  • Senior cloud or DevOps profile: between 60,000 and 85,000 euros.
  • Experienced cloud architect: beyond 80,000 euros, more in large metropolitan areas or in consulting.

The most valued skills: Kubernetes, Terraform, cloud security, FinOps, and the ability to articulate technology and business stakes.

12. Should I learn Kubernetes at the same time?

No, learn the cloud first. Kubernetes is a layer on top of the cloud, and it is much easier to understand when you already master the notions of virtual machine, virtual network, load balancer and storage.

Recommended order: Linux → Docker → cloud → CI/CD → Kubernetes.

Our Kubernetes discovery course precisely assumes these basics are acquired.

13. How to convince my management to migrate to the cloud?

Speak in business terms, not technical terms:

  • Speed: "launching a new service would take two days instead of four months".
  • Cash flow: "no upfront investment, a monthly expense proportional to usage".
  • Risk: "our backups would be replicated on three sites instead of one".
  • Recruiting: "competent candidates want to work on current technologies".
  • Elasticity: quantify what the last load peak cost in downtime.

Effective tactic: propose a pilot migration on a non-critical application, with a capped budget and quantified success criteria. It is far more convincing than a global project.

14. Where to start concretely tomorrow morning?

A five-day plan, entirely free:

  1. Day 1 — Create an account at a provider. Immediately configure a budget alert at 5 euros. Enable two-factor authentication.
  2. Day 2 — Create a virtual machine, connect via SSH, install a web server, display a page. Delete everything at the end.
  3. Day 3 — Deploy a container on a managed service: Cloud Run, App Runner or Container Apps. Note the difference in simplicity with day 2.
  4. Day 4 — Create object storage, upload files, configure the permissions. Understand why public access is dangerous.
  5. Day 5 — Explore the detailed bill. Identify what cost what. It is the most underestimated skill of the field.

Then: prepare a fundamental certification, and deploy a real personal project.

7. What you learned in this course​

You now have the complete cloud culture — the one expected for a fundamental certification, for an interview, or to usefully participate in an architecture choice.

8. Your next step​

Path 1 · Complete your technical culture​

Path 2 · Aim for a certification​

Start with the fundamental certification of the provider of your choice: AWS Cloud Practitioner, Azure Fundamentals (AZ-900) or Google Cloud Digital Leader. This course plus a few weeks of practice are enough.

Path 3 · Move to practice​

Apply the five-day plan from question 14. Everything is achievable within the free tiers. The important thing is to create a real resource, then delete it.

Our paid plans give access to the Premium courses to go much further, notably the Premium Terraform course to drive your cloud entirely with code.

9. One last piece of advice​

The cloud is learned by practising it, not by reading about it. You can read ten articles about availability zones; you will really understand the day you have configured two of them and cut one off to see what happens.

Create an account tonight. Configure the budget alert. Launch a machine. Install a web server. Display "hello" in your browser from a machine that did not exist ten minutes ago and will no longer exist in an hour.

It is that precise moment that makes you understand what the cloud really is.

Remember in 30 seconds​

  • Netflix took seven years to migrate — and keeps its own video delivery network, where egress would cost too much.
  • Spotify chose Google Cloud for a single decisive service: BigQuery.
  • In the public sector and regulated industries, the cloud choice is first legal (SecNumCloud, CLOUD Act).
  • A three-person startup today serves a worldwide market for 50 euros per month — impossible before 2006.
  • Repatriation exists and is justified: a load stable over five years deserves an honest comparative calculation.
  • Learn one cloud seriously rather than three superficially — the concepts are transferable.
  • A budget alert as soon as the account is created, and never an access key in Git.
  • The administrator's job does not disappear, it moves towards automation, security and costs.
  • The cloud is learned by practising it. Create, break, delete.

Thank you for taking this cloud discovery course! 🎉

Want to continue? Back to the table of contents or move on to the Terraform course to learn to create all of this with code.

Last step: take the end-of-course quiz — five corrected and explained questions, three minutes, to verify that the essentials are acquired.