Keep the cloudalive at 2AM.
Production is melting and you are the only engineer awake. Read the symptoms, fix the real config in a live terminal, and apply it before your SLA hits the floor.
- Levels
- 0levels
- Installs
- 0installs
- SLA floor
- 0%SLA floor to survive
Fix real configs for
- nginx
- PostgreSQL
- Docker Compose
- Redis
- HAProxy
- Kafka
- Gunicorn
- Elasticsearch
- Kubernetes
How it works
One shift, four moves
Every level follows the loop real incidents follow. Do it well and the SLA climbs back; rush it and you pay for it.
- 01
Read the symptoms
Live logs, netstat and systemctl status tell you what is failing. There are no hints about target numbers — you read the evidence.
- 02
Fix the real config
Open the file in nano or use sed, exactly as you would on a production box. Nothing is pre-filled for you.
- 03
Apply it the right way
Reload or restart? systemctl or kubectl? Picking the wrong way costs you error budget.
- 04
Survive the traffic wave
Partway through each level, load ramps up. A config that passed a moment ago can fall over — size it with headroom.
The curriculum
Ten levels, one stack at a time
Start with a web server and finish with a full Black Friday outage across web, workers and database.
- 1nginx
Web Server
Worker limits, timeouts and body size
systemctl reload nginx - 2PostgreSQL
Database
Why some settings need a restart, not a reload
systemctl restart postgresql - 3Docker Compose
Full Stack Under Load
Replicas, memory and CPU limits
docker-compose up -d - 4Redis
Cache
Memory ceilings and eviction policy
systemctl restart redis - 5HAProxy
Load Balancer
Connection caps, timeouts and balancing
systemctl reload haproxy - 6Kafka
Message Queue
Partitions, replication and retention
systemctl restart kafka - 7Gunicorn
App Server
Concurrency and slow-request budgets
systemctl reload gunicorn - 8Elasticsearch
Search Cluster
Heap safety and indexing back-pressure
systemctl restart elasticsearch - 9Kubernetes
Kubernetes
Readiness probes and safe rollouts
kubectl apply -f /opt/cloudrush/k8s/deployment.yaml - 10FinaleDocker Compose
Black Friday
Every layer at once, under surge traffic
docker-compose up -d
Built for practice
Pressure without the pager
A real shell in your browser
Commands run in a sandboxed Node environment inside the page. Edit files, run commands, see real output.
Live SLA pressure
Uptime drains while checks fail and recovers when you fix them. Below 90% the shift is over.
An error budget
Five free failed applies per level. After that, every bad deploy costs real SLA.
5 free failed applies
Ten escalating levels
From a single nginx file to a full multi-service stack, each level adds a new tool and a new way to break.
Nothing to install
Open the page and start your shift. Progress is saved in your browser.
- No virtual machine
- No Docker
- No cloud account
Learn by consequence
Every directive has a reference entry explaining why the wrong value hurts.
keepalive_timeout 0;Every request pays a fresh TCP + TLS handshake. Under load, latency climbs and queues build.
FAQ
Before you clock in
Do I need to install anything?
No. The terminal runs entirely in your browser using a sandboxed Node.js environment. There is no server to set up and nothing touches your machine.
Is this a real server I am editing?
It is a real shell with real files, but a sandboxed one. The configs are realistic, and the game checks the values you set the same way an operator would judge them under load.
Which browsers work?
A current desktop Chromium-based browser such as Chrome or Edge gives the best experience. The terminal drawer also works on phones, but a keyboard makes the game far more enjoyable.
Do I need to be an SRE already?
No. The first levels are gentle, the Config Reference explains every directive, and you can retry any level. It is a good way to build intuition for how services behave under load.
Is my progress saved?
Yes, in your browser. Close the tab and come back later — the start screen offers to continue from the level you unlocked.
Your shift starts now
The pager is going off. Open the terminal and bring the SLA back above the line.