Description: There's a Kubernetes Deployment with an Nginx pod and a Load Balancer declared in the manifest.yml file. The pod is not coming up. Fix it so that you can access the Nginx container through the Load Balancer.
There's no "sudo" (root) access.
Test: Running curl 10.43.216.196 returns the default Nginx Welcome page.
See /home/admin/agent/check.sh for the test that "Check My Solution" runs.
Scenario: "Manhattan": can't write data into database.
Level: Medium
Type: Fix
Access: Public
Description: Your objective is to be able to insert a row in an existing Postgres database. The issue is not specific to Postgres and you don't need to know details about it (although it may help).
Helpful Postgres information: it's a service that listens to a port (:5432) and writes to disk in a data directory, the location of which is defined in the data_directory parameter of the configuration file /etc/postgresql/14/main/postgresql.conf. In our case Postgres is managed by systemd as a unit with name postgresql.
Description: There's a web server serving a file /var/www/html/index.html with content "hello sadserver" but when we try to check it locally with an HTTP client like curl 127.0.0.1:80, nothing is returned. This scenario is not about the particular web server configuration and you only need to have general knowledge about how web servers work.
Test:curl 127.0.0.1:80 should return: hello sadserver
Description: There's an Nginx web server installed and managed by systemd. Running curl -I 127.0.0.1:80 returns curl: (7) Failed to connect to localhost port 80: Connection refused , fix it so when you curl you get the default Nginx page.
Test:curl -Is 127.0.0.1:80|head -1 returns HTTP/1.1 200 OK
Description: There's a "dockerized" Node.js web application in the /home/admin/app directory. Create a Docker container so you get a web app on port :8888 and can curl to it. For the solution to be valid, there should be only one running Docker container.
Test:curl localhost:8888 returns Hello World! from a running container.
Description: There is a Python WSGI web application file at /home/admin/wsgi.py , the purpose of which is to serve the string "Hello, world!". This file is served by a Gunicorn server which is fronted by an nginx server (both servers managed by systemd). So the flow of an HTTP request is: Web Client (curl) -> Nginx -> Gunicorn -> wsgi.py . The objective is to be able to curl the localhost (on default port :80) and get back "Hello, world!", using the current setup.
Test:curl -s http://localhost returns Hello, world! (serving the wsgi.py file via Gunicorn and Nginx)
Description: There's an etcd server running on https://localhost:2379 , get the value for the key "foo", ie etcdctl get foo or curl https://localhost:2379/v2/keys/foo
Description: Given the CSV file /home/admin/table_tableau11.csv, find the Electoral District Name/Nom de circonscription that has the largest number of Rejected Ballots/Bulletins rejetés and also has a population of less than 100,000.
The initial CSV file may be corrupted or invalid in a way that can be fixed without changing its data.
Installed in the VM are: Python3, Go, sqlite3, miller directly and PostgreSQL, MySQL in Docker images.
Save the solution in the /home/admin/mysolution , with the name as it is in the file, for example: echo "Trois-Rivières" > ~/mysolution (the solution must be terminated by newline).
Description: There are two pods: "logger" and "logshipper" living in the default namespace. Unfortunately, logshipper has an issue (crashlooping) and is forbidden to see what logger is trying to say. Could you help fix Logshipper?
Do not change the K8S definition of the logshipper pod. Use "sudo".
Because k8s takes a minute or two to change the pod state initially, the check for the scenario is made to fail in the first two minutes.
Description: There are three Docker containers defined in the docker-compose.yml file: an HAProxy accepting connetions on port :5000 of the host, and two nginx containers, not exposed to the host.
The person who tried to set this up wanted to have HAProxy in front of the (backend or upstream) nginx containers load-balancing them but something is not working.
Test: Running curl localhost:5000 several times returns both hello there from nginx_0 and hello there from nginx_1
Check /home/admin/agent/check.sh for the test that "Check My Solution" runs.
Scenario: "Warsaw": Prometheus can't scrape the webserver
Level: Medium
Type: Fix
Access: Paid
Description: A developer created a golang application that is exposing the /metrics endpoint. They have a problem with scraping the metrics from the application. They asked you to help find the problem.
Full source code of the application is available at the /home/admin/app directory.
"Moyogalpa": Security Snag. The Trials of Mary and John
Scenario: "Moyogalpa": Security Snag. The Trials of Mary and John
Level: Medium
Type: Fix
Access: Email
Description: Mary and John are working on a Golang web application, and the security team has asked them to implement security measures. Unfortunately, they have broken the application, and it no longer functions. They need your help to fix it.
The fixed application should be able to allow clients to communicate with the application over HTTPS without ignoring any checks. (eg: curl https://webapp:7000/users.html) and serve its static files.
Test:curl https://webapp:7000/users.html should return the content of file.
The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can see and execute.
"Helsingør": The first walls of postgres physical replication
Scenario: "Helsingør": The first walls of postgres physical replication
Level: Medium
Type: Fix
Access: Email
Description: You're setting up a PostgreSQL database with replication, you decided to use Docker along with Docker Compose to make it easier to manage and test, after a few hours of work you finished the job and the master database is up and running, but you're having trouble with the replica.
You need to figure out what's wrong with the replica and fix it.
Since you are using Docker Compose, you can check the status of the running containers using docker compose ps or docker ps will do the job too). You may also want to check the logs of the containers.
All definition for the containers are inside the docker-compose.yml file. You can stand up the environment by running docker compose up -d and set it down by running `docker compose down`.
If you make any change to the docker-compose.yml file, you can restart the containers by running docker compose up -d --force-recreate.
Test: Postgres replica container works.
The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can see and execute.
Description: There is an nginx service running on port 443, it is the main web server for the company and looks like a new employee has deployed some changes to the configuration of supervisor and now it is not working as expected.
If you try to access curl -k https://bekasi it should return Hello SadServers! but for some reason it is not.
You cannot modify files from the /home/admin/bekasi folder in order to pass the check.sh
Scenario: "Karakorum": WTFIT – What The Fun Is This?
Level: Hard
Type: Fix
Access: Paid
Description: There's a binary at /home/admin/wtfit that nobody knows how it works or what it does ("what the fun is this"). Someone remembers something about wtfit needing to communicate to a service in order to start. Run this wtfit program so it doesn't exit with an error, fixing or working around things that you need but are broken in this server. (Note that you can open more than one web "terminal").
Scenario: "Hong-Kong": can't write data into database.
Level: Hard
Type: Fix
Access: Email
Description: (Similar to "Manhattan" scenario but harder). Your objective is to be able to insert a row in an existing Postgres database. The issue is not specific to Postgres and you don't need to know details about it (although it may help).
Postgres information: it's a service that listens to a port (:5432) and writes to disk in a data directory, the location of which is defined in the data_directory parameter of the configuration file /etc/postgresql/14/main/postgresql.conf. In our case Postgres is managed by systemd as a unit with name postgresql.
Description: A user client was added to the server, as well as their SSH public key. The objective is to be able to SSH locally (there's only one server) as this user client using their ssh keys. This is, if as root you change to this user sudo su; su client, you should be able to login with ssh: ssh localhost.
Test: As user admin: sudo -u client ssh client@localhost 'pwd' returns /home/client
There is a one-class Java application in your /home/admin directory. Running the program will print out a secret code, or you may be able to extract the secret from the class file without executing it but I'm not providing any special tools for that.
Put the secret code in a /home/admin/solution file, eg echo "code" > /home/admin/solution.
Description: There is a RabbitMQ (RMQ) cluster defined in a docker-compose.yml file.
Bring this system up and then run the producer.py script in such a way that is able to send messages to RMQ. In particular you have to send the message "hello-lwc".
- RMQ is a queuing system: messages are put in the queue with a "producer" and they are taken out from the other side by a "consumer". The queue name has to be the same for both.
- To send the message "hello-lwc": python3 ~/producer.py hello-lwc. Should return Message sent to RabbitMQ. "IncompatibleProtocolError" means RMQ is not working properly.
- To test consuming it: python3 ~/consumer.py, this will retrieve the next message from the queue and print it. Once everything is working send more than one message so there's at least one in the queue when the validation runs.
- Do not change the consumer.py and producer.py files; if you do the Check My Solution will fail.
Test:python3 ~/consumer.py returns hello-lwc
See /home/admin/agent/check.sh for the exact test.
Description: You are working as a DevOps Engineer in a company and another team member left the company and left the docker-compose.yml of a database-backed web application unfinished.
Generally, the problem revolves around the database migration and docker compose.
Additionally on front of the application there is an Nginx server and you need to fix the proper access to it as well.
