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.

Credit Kamil Błaż

Test: The endpoint http://localhost:9000/metrics should return HTTP code 200.

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can see and execute.

Time to Solve: 60 minutes.

Scenario: "Ravenna": Logs Missing in ELK Pipeline

Level: Medium

Type: Fix

Access: Paid

Description: You are on call for the orders-api service. Central logging uses a small ELK stack on Docker Compose: an application container, Filebeat, Logstash, and Elasticsearch.

Operations reports that no order events show up in Elasticsearch, even though the application container is healthy and keeps writing logs. SRE left notes that the service contract specifies plain-text log lines.

The stack lives under /home/admin/ravenna and is managed with Docker Compose. Elasticsearch is reachable on the VM at http://127.0.0.1:9200.

Notes: 1. Wait until all four containers are Up before debugging (docker compose -f /home/admin/ravenna/docker-compose.yml ps). Elasticsearch can take up to two minutes to become healthy.
2. Internet access is not needed; container images are preloaded in the local Docker engine.

Test: At least one document containing order_shipped is indexed in Elasticsearch under the orders-* index pattern.

Quick check:

 curl -s 'http://127.0.0.1:9200/orders-*/_search?q=order_shipped&size=1' | jq . 

The "Check My Solution" button runs the script /home/admin/agent/check.sh, which you can read and execute.

Time to Solve: 30 minutes.