What the cloud is

QuickCart’s problem isn’t one server. It’s that owning servers means guessing, in advance, how much you’ll ever need, then paying for that guess every hour of every day.

This lesson is about what the cloud really is, who is responsible for what, and how to keep an eye on the bill from the first day.

The cloud is renting computers from someone else, by the second, instead of buying them. The computers sit in the provider’s buildings. You start them, use them and delete them from a web page or a command, and you pay only while they exist.

This course uses AWS, Amazon Web Services, the largest cloud provider. Google Cloud and Microsoft Azure work the same way under different names.

What changes when you rent

Most AWS servers running Linux are billed per second, with a minimum of 60 seconds each time one starts. Other services charge per hour, per gigabyte stored or per request. Prices change and differ by region, so this course gives rough figures and always says so.

Regions: where the computers are

AWS runs its computers in regions: separate groups of data centres in different parts of the world, such as us-east-1 in Northern Virginia or eu-west-2 in London. There are more than 30.

You choose a region for almost everything you create, and each region is independent. A server in us-east-1 doesn’t appear in the list for London. Regions and zones explains why QuickCart uses two buildings inside one region.

A few services aren’t tied to a region: they’re global. IAM, which controls who can do what, is the one you’ll meet first.

Services: the pieces you rent

AWS has hundreds of services. This course uses about fifteen. These are the ones you’ll meet first:

Who is responsible for what

Renting a server doesn’t mean AWS looks after everything on it. AWS calls the split the shared responsibility model: AWS is responsible for the security of the cloud, and you’re responsible for security in the cloud.

The more managed a service is, the more AWS takes on. With EC2 you patch the operating system. With RDS, AWS patches the database software, but who can connect is still up to you.

A database left open to the internet is never AWS’s fault. The setting was yours.

Keeping the bill under control

The cloud’s biggest strength, paying for what exists, is also how people get surprised. Three habits prevent almost every surprise:

Below is one day of QuickCart orders, as the number of servers needed each hour. The dashed line is how many servers QuickCart owns. Pick a day and a number of servers, then play the day and compare owning with renting.

What to notice: on the rush days there’s no good number to own. Own few and you turn orders away at dinner; own many and most of them sit idle and paid for, all day. Renting follows the bars. Owning only wins when the load is flat and predictable.

Free — looking around the console and creating a budget that emails you costs nothing.

You’ll find the four things you’ll use in every lab: the region selector, your account ID, the billing pages, and a budget that warns you before a surprise. About 15 minutes.

You need an AWS account you can sign in to. If you’re signing in as the root user, the email address the account was created with, that’s fine for this lab only. Who can do what: IAM shows why you should stop using it straight afterwards.

1. Find the region selector

   Sign in to the AWS console. Look at the top right of the page, next to your account name.

   You should see

   A region name such as N. Virginia or Ireland. Open it: a list of regions with their codes, like US East (N. Virginia) us-east-1.

   Choose US East (N. Virginia) us-east-1. This course uses it for every lab.

   Now type IAM in the search bar at the top and open it.

   You should see

   The region selector now says Global and can’t be changed. IAM is one of the few services that isn’t tied to a region.

2. Find your account ID

   Choose your account name at the top right of the console.

   You should see

   A menu showing Account ID, a 12-digit number with a copy button. In this course it’s always shown as 111122223333. Wherever you see that, use your own.

   Copy it somewhere handy. You’ll need it for bucket names and permissions later. An account ID isn’t a secret on its own, but there’s no reason to post it publicly either.

3. Open the billing home page

   AWSIn the AWS console: Billing and Cost Management→Home

   You should see

   A summary of this month’s costs so far, a forecast for the month, and your costs broken down by service. In a new account, everything is $0.00 or close to it.

   Now open Free Tier in the left menu of the same page.

   You should see

   What your account can use for free, and how much of it you’ve used this month. What’s free depends on when your account was created and changes over time, so check here rather than relying on any list you read elsewhere, including this one.

4. Create a budget that emails you

   AWSIn the AWS console: Billing and Cost Management→Budgets→Create budget

   Field	Enter
   Budget setup	Use a template (simplified)
   Templates	Monthly cost budget
   Budget name	quickcart-monthly
   Enter your budgeted amount ($)	10.00, or whatever you’re comfortable spending on this course each month
   Email recipients	your own email address

   Choose Create budget.

   You should see

   quickcart-monthly in the list of budgets. The template sets up three alerts for you: when actual spending reaches 85% and 100% of the amount, and when the forecast for the month is going to pass 100%.

   If you’d rather hear about the very first cent, choose the Zero spend budget template instead. It emails you as soon as anything costs money.

   A budget that only sends email is free. AWS charges only for large numbers of budgets, or ones that take actions for you. Check Budgets pricing if you ever go past a couple.

5. Clean-up step: Clean up

   Nothing to delete: you only looked around, and the budget is free.

   Keep the budget. It’s the one thing from this lab worth leaving in place for the whole course. If you do want to remove it later:

   AWSIn the AWS console: Billing and Cost Management→Budgets→quickcart-monthly→Actions→Delete

   You should see

   On the billing home page, this month’s costs are still $0.00, or a few cents at most.