Operator SDK basics in Kubernetes - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Operator SDK: Initializing a new operator project

What is the output when you run operator-sdk init --domain=example.com --repo=github.com/example/memcached-operator in an empty directory?

A Creates a new operator project with Go modules initialized and a basic directory structure including API and controllers folders.

B Throws an error because the --repo flag is missing a version number.

C Initializes a Helm chart inside the directory instead of a Go operator project.

D Outputs a warning that the domain is invalid and aborts the initialization.

💡 Hint

The init command sets up the project structure and Go modules for a new operator.

The operator-sdk init command creates a new operator project with the specified domain and repository path. It initializes Go modules and creates folders like api and controllers for further development.

🧠 Conceptual

intermediate

Understanding Operator SDK project structure

Which folder in an Operator SDK Go project contains the Custom Resource Definitions (CRDs) and API types?

A controllers

B api

C config

D build

💡 Hint

Think about where you define the schema and types for your custom resources.

The api folder contains the API definitions and Custom Resource Definitions (CRDs) for the operator. It holds the Go structs that define the custom resource schema.

🔀 Workflow

advanced

Operator SDK: Adding a new API version

You want to add a new version v2 to your existing API group memcached.example.com. Which command correctly adds this new version?

A operator-sdk generate api --group memcached --version v2 --kind Memcached

B operator-sdk add api --group memcached --version v2 --kind Memcached

C operator-sdk init --group memcached --version v2 --kind Memcached

D operator-sdk create api --group memcached --version v2 --kind Memcached --resource --controller

💡 Hint

Use the command that creates API and controller code for a new version.

The create api command adds a new API version and generates resource and controller code. The init command is for project creation, and generate api is not a valid command.

❓ Troubleshoot

advanced

Operator SDK: Debugging a failed operator build

You run make docker-build but get an error: cannot find module providing package sigs.k8s.io/controller-runtime. What is the most likely cause?

A The Go modules are not properly initialized or dependencies are missing in go.mod.

B Docker daemon is not running, so the build cannot access the network.

C The operator-sdk CLI version is outdated and incompatible with the project.

D The Kubernetes cluster is not reachable, causing the build to fail.

💡 Hint

Check if your Go dependencies are correctly set up before building.

The error indicates missing Go dependencies. This usually happens if go.mod or go.sum files are missing or if 'go mod tidy' was not run to fetch dependencies.

✅ Best Practice

expert

Operator SDK: Recommended way to test your operator locally

Which approach is the best practice to test your Operator SDK Go operator locally before deploying to a Kubernetes cluster?

A Build the operator image and push it to Docker Hub, then deploy it to a remote cluster.

B Use <code>operator-sdk test local</code> to run end-to-end tests against a live cluster.

C Run the operator binary locally with <code>make run</code> and connect to a local kind cluster.

D Manually apply CRDs and resources using kubectl without running the operator binary.

💡 Hint

Local testing usually involves running the operator process directly connected to a test cluster.

Running the operator binary locally with 'make run' allows you to debug and test your operator against a local Kubernetes cluster like kind or minikube before building and deploying images.