Almost every scare with the AWS bill could have been avoided with a timely email: a machine somebody left running, a data transfer that spiked, a paid service enabled by mistake. AWS Budgets sends that email. You define how much you consider normal to spend per month and it warns you when actual spend or the forecast exceeds it. The first budgets cost nothing, and setting one up takes five minutes.
This is, by far, the best effort-to-benefit measure in an entire AWS account. If you do only one thing from this section of guides, make it this one.
Before you start: what each thing means
- AWS Budgets
- Amazon's budgeting service: you tell it how much you expect to spend and it warns you when you get close or go over.
- Actual spend
- What you have spent in the month up to today.
- Forecast
- What AWS calculates you will spend by month end if you keep up the current pace. It is the alert that arrives in time.
- Threshold
- The percentage of the budget at which the alert triggers (for example, 80 %).
- Linked account
- Each of the AWS accounts that hang off a main payer account, when a company has several.
- Cost allocation tag
- A tag (name = value) you attach to your resources and enable in Billing so you can budget by project.
Step by step
Decide the figure
Open Billing and Cost Management, Bills, and look at the last three closed months. Your budget is a little above the highest normal month: if you spend between 180 and 220 dollars, set 250. Do not set it so high that it never triggers, nor so tight that it warns you every month for nothing.
Create the budget
In the menu on the left, Budgets, Create budget. Choose Customize (advanced) to see all the options, type Cost budget. Period Monthly, recurring renewal, fixed amount with the figure from step 1. Give it a clear name, for example
Gasto mensual total. Leave the scope at all services, unless you want to watch something specific.Add the first alert: actual spend at 80 %
Next, Add an alert threshold. Threshold 80 % of the budgeted amount, based on Actual spend. Recipients: one or more email addresses separated by commas. Make them addresses somebody actually reads, not a generic mailbox.
Add the second alert: forecast at 100 %
Another threshold: 100 %, based on the Forecasted spend. Mid-month, AWS works out how much you will have spent by month end at the current pace; this alert triggers when that forecast exceeds your budget, even if you have not spent it yet. It is the useful alert, because it arrives with time to spare to switch off whatever is surplus.
If you want a third one, 100 % actual: it means you have already gone over, and that is worth knowing too.
Review and create
Next, go over the summary and Create budget. It appears in the list with current spend, the forecast and a progress bar. Alerts come from an AWS address; add it to your safe senders if your email is strict about spam. Budgets update several times a day, not instantly.
Repeat for what really matters to you
One budget per account if you have several in an organization; one per project if you tag your resources (filtering by cost allocation tag); or one per service for the one that worries you most, such as data transfer. Review the figures once a quarter: the business changes and the budget should too.
What can go wrong
No alert arrives even though I have gone over
Check that the address is spelled correctly and that the AWS email is not in spam. And bear in mind that billing data takes hours to update: spend from this morning may not count until tonight.
It warns me every month and I no longer pay attention
The budget is badly sized or spend has grown legitimately. Raise it to a realistic figure. An alert that is ignored is worse than none.
I want it to act, not just warn
Budgets allows actions: applying an IAM policy that blocks creating new resources, or stopping specific EC2 or RDS instances when a threshold is exceeded. It is powerful, but it can also stop production if set up carelessly. Start with alerts; add actions only for test machines.
I see the budget in one account but not in the others
Budgets are per account. In an organization, create them in the payer account filtering by linked account, and that way you have them all in one place.
In Simplio
In Simplio the Costs screen shows what has been billed this month to date, the end-of-month forecast and the previous month for each AWS account, in dollars and in euros, and a per-user budget caps what each person can create from Simplio. If a budget is exceeded, it warns you by email, for all your accounts from the same screen.
The same task, in AWS and in Simplio
| In the AWS console | In Simplio | |
|---|---|---|
| Alert if spend spikes | Budgets, create budget, two thresholds, recipients: 5 steps per account | Budget per account and per user from the Costs screen, with notice by email |
| See where you stand today | Open Budgets or Cost Explorer | This month, forecast and last month when you open Simplio |
| Several accounts | One budget in each | All on the same screen |