Challenge on ,
Troubleshoot an Ingress That Returns 503 Service Unavailable
by Omkar Shelke
A railway app publishes two endpoints through an Ingress, and both return 503. Find out why and make both endpoints answer again.
Challenges
Focused, hands-on DevOps and server-side problems with hints, feedback, and automated solution checks.
Challenge on ,
Run the Application's Test Suite in a Container Without Network Access
You are containerizing the dev workflows of a legacy Python service and you need to find out which external services its test suite talks to. Can you think of an easy way to do it?
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Turn Off a Feature Flag in a Production Redis Server Using a Local Containerized redis-cli
Ad-hoc containers are a handy way to run command-line tools without installing them on the host. Use one to access a production Redis server and turn off a feature flag. But beware of the gotcha: the production server can only be tunneled to the localhost.
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Docker 101: Publish All Exposed Ports on Random Host Ports to Avoid Port Conflicts
Can you get several builds of an app running side by side without port conflicts, so you can test them simultaneously?
Challenge on ,
Migrate a Traefik Ingress to the Gateway API and Cut Traffic Over
by Omkar Shelke
The storefront APIs are served through a Traefik Ingress with TLS and two path rules. Reproduce that configuration with a Gateway and an HTTPRoute on the same hostname, cut traffic over to it, and retire the Ingress.
Challenge on ,
Call an HTTP API with curl: Creating, Updating, and Deleting Resources
Practice calling HTTP APIs from the command line: send JSON bodies with POST, PUT, and PATCH, upload a file, delete a resource, and read the status codes the server answers with.
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Identify the Source of Unexpected Requests in a Kubernetes Cluster
An internal service started receiving requests from unexpected IP addresses. Identify the unexpected sources and find out which workloads and teams are behind them.
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Identify the Source of Unexpected Requests in an On-Prem Network
An internal service started receiving requests from unexpected IP addresses. Identify the unexpected sources and find out which systems are behind them.
Challenge on ,
Access a Private Kubernetes API Server Through an SSH SOCKS Proxy
The production Kubernetes cluster lives inside a private VPC, and its API server has no public endpoint. Turn an SSH connection to the bastion host into a SOCKS proxy and teach kubectl to use it, so the cluster becomes manageable from your workstation.
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Extend the Cluster with an Additional Service CIDR for the dev Team
by Omkar Shelke
Add a new, separate Service CIDR range for the dev team using the ServiceCIDR API object — without touching or restarting the cluster's default Service CIDR — then create a Service with an explicit ClusterIP inside that new range and verify DNS resolution.