General

Saturday Outage #04 (AWS S3): the missing electricity bills

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Intermediate
1 h 30 min
1,000 credits
First lab free

Description

Saturday, 9:10 a.m. Mireille, from customer service at Fujima, the electricity supplier of Yaoundé, calls you: forty-one complaints since Thursday. July bills that won't open anymore, October bills nowhere to be found, and since last night no new bill at all. The CEO found out on Facebook. Serge, the developer, "tightened the security of the bills" before leaving on vacation. Three errors hide the bills in the Amazon S3 bucket. Find them and fix them: a lifecycle rule in too much of a hurry, bills filed under the wrong path, KMS encryption that blocks the generator. Then the CEO's real request: know before the customers do. You connect the upload measurements and set up two CloudWatch alarms that send an email when a bill is late or when nothing arrives anymore. Saturday Outage is a challenge with no step-by-step guide: one mission, one broken sandbox, two hours. The solution comes out the following Saturday, along with the next outage.

Important

The sandbox lives two hours, provisioning included: read the mission before launching. Fix Fujima's bucket and generator, don't rebuild them, and name your topic and alarms with your prefix. Two conditions cancel the validation: bills no longer encrypted with Fujima's key, and a generator that can use every KMS key.

Tip

Act like a customer: the portail-abonnes function answers exactly what the app sees. Test it before and after each fix, and keep the generator's logs open in another tab.

Skills you will practise

Choose an S3 storage class based on access time, and write a lifecycle rule that saves money without hurting customers
Restore objects archived in S3 Glacier, then bring them back for good into an accessible class
File S3 objects under the right prefix, where an application looks for them
Diagnose an upload refused by SSE-KMS encryption and give a role the one permission it is missing
Connect a Lambda function to the events of an S3 bucket
Create CloudWatch alarms that send an email when a service slows down or stops

Technologies used

Amazon S3
S3 Glacier
AWS KMS
AWS Lambda
Amazon CloudWatch
Amazon SNS
AWS IAM
Console AWS

Prerequisites

Having created an S3 bucket with a lifecycle rule (lab 2 of the AWS path)
Knowing how to read a Lambda function's logs and role (lab 7 of the AWS path)
Enjoying the hunt: the challenge guides you with reminders and hints, and you are the one who finds the fault

aws
s3
glacier
kms
cloudwatch
monitoring
challenge
saturday outage

At a glance

Domain: Cloud
Level: Intermediate
Estimated time: 1 h 30 min
Sandbox: 2 h, then deleted automatically
Languages: French, English
Updated on: 24 October 2026