Lab catalog
77 labs · 11 tracks77 of 77loading…
Loading…
-
Write a healthcheck to a contract The deploy needs a script that tells whether an address is ready for traffic. The answer is an OK or FAIL line and an exit status, even when the server stays silent.Bash: text processing and scripts ~25 min not started
-
A service restarts in a loop Since an update, the marketplace feed service restarts every few seconds, and the feed is not refreshed. Find what stops it and fix it so that it runs within the memory it is given.Inside the system: resources, kernel, processes ~25 min not started
-
A build runs out of memory The nightly search index build fails for lack of memory, and it cannot be given more RAM. Give the machine a swap file that survives a reboot and set how readily the system uses it.Inside the system: resources, kernel, processes ~20 min not started
-
A service fails under load The notification service keeps one connection per subscriber. There are now three hundred subscribers, and it works one moment and fails the next, even though a colleague has already changed something. Find the cause and fix it so that the service holds a thousand subscribers, including after a restart.Inside the system: resources, kernel, processes ~25 min not started
-
A kernel setting disappears The service that receives the warehouse sensor readings started working once a colleague raised a kernel parameter for it. After a reboot overnight it fails to start again, although the colleague insists the setting was saved. Make the value survive a reboot and keep the rest of the server settings as they were.Inside the system: resources, kernel, processes ~20 min not started
-
An application exits silently After moving to a new server, the warehouse inventory service will not start — and says not a word about why. Find the cause from what the process does and fix it so that the service survives a restart and nobody gets permissions they should not have.Inside the system: resources, kernel, processes ~25 min not started
-
A service holds up the boot After every reboot the warehouse waits for half a minute, and the order desk never comes up — someone starts it by hand later. A colleague insists the service dependencies are set up. Make the order desk come up on its own after a reboot without holding up the boot.Inside the system: resources, kernel, processes ~25 min not started
-
The clocks of two machines drift apart The reports from the node1 server are two hours ahead, and the events in the logs of node1 and node2 do not line up. The office time comes from node2. Make the node1 clock follow node2 — now and after the time service restarts.Inside the system: resources, kernel, processes ~25 min not started
-
Two sites on one nginx The blog address opens the company site. Give each name its own site back without breaking the rest.Web stack ~20 min not started
-
Set up an nginx reverse proxy The backend listens only on 127.0.0.1:3000 — publish it through nginx on port 80.Web stack ~25 min not started
-
Fix 502 Bad Gateway The notes service is running, but the site in front of it answers 502. Find where the path from nginx to the application breaks and fix it so that the site survives a service restart.Web stack ~25 min not started
-
The portal fails over HTTPS Browsers no longer open the company portal over HTTPS. Give the portal a working certificate from the training CA and keep the existing key.Web stack ~25 min not started
-
The shop after a certificate renewal Since the shop's certificate was renewed, some clients reject it, and links from an old newsletter land on the home page. Fix the shop's HTTPS and the redirect to it.Web stack ~25 min not started
-
App can't connect to PostgreSQL A service fails on start with a database connection error, although PostgreSQL is running. Give it password access back.Web stack ~25 min not started
-
Restore a database from a dump After a release, an order disappeared from the shop database and some amounts changed. Bring up a copy of the database as it was before the failure, next to the damaged one, without touching it.Web stack ~25 min not started
-
Too much is visible from the network The warehouse server runs a site, a database and an admin panel, and only the site and SSH should be visible from the network. Find what else is open to the outside and close it so that everything still works on the server itself, after a reboot too.Server security ~35 min not started
-
After the update A colleague installed security updates and the packages are new, yet the scanner still flags the server as vulnerable. Find the services running old code and restart only those.Server security ~25 min not started
-
A password can be anything Interns change their own passwords and the system accepts any of them, while guessing a password can go on forever. Introduce a password policy and a lockout after failed attempts without losing your own key login and sudo.Server security ~30 min not started
-
The brute force goes on Someone on the neighbouring machine keeps trying to log in to the server's SSH. fail2ban is installed and running, a colleague has even tuned it, and still there is no ban. Find out why and make sure the attacker gets banned and the administrator never does.Server security ~30 min not started
-
The service can do anything The helpdesk ticket service runs as root without a single restriction — that has to change before the security review. Restrict it with systemd so that it keeps taking and storing tickets.Server security ~25 min not started
No lab on the topic you need? Suggest a lab