Debugging service connectivity in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the first step to check when a Kubernetes service is not reachable?

Check if the pods behind the service are running and ready using kubectl get pods and kubectl describe pod <pod-name>.

beginner

How can you verify the endpoints associated with a Kubernetes service?

Use kubectl get endpoints <service-name> to see which pod IPs and ports the service routes to.

intermediate

What command helps you test connectivity from inside a pod to a service?

Use kubectl exec -it <pod-name> -- curl <service-name>:<port> to test if the service is reachable from the pod.

intermediate

Why is checking the service type important when debugging connectivity?

Because service types like ClusterIP, NodePort, and LoadBalancer expose services differently, affecting how you can access them.

advanced

What role do Network Policies play in service connectivity?

Network Policies can restrict or allow traffic to pods, so misconfigured policies can block service access.

Which command shows the pods behind a Kubernetes service?

A kubectl get services

B kubectl get endpoints <service-name>

C kubectl get nodes

D kubectl describe pod <pod-name>

The kubectl get endpoints command lists the pods IPs and ports that a service routes to.

What does a ClusterIP service type do?

A Blocks all traffic to the service

B Exposes the service on each node's IP at a static port

C Exposes the service only inside the cluster

D Exposes the service externally using a cloud provider's load balancer

ClusterIP exposes the service only inside the Kubernetes cluster.

How can you test if a pod can reach a service?

A kubectl logs <pod-name>

B kubectl get pods

C kubectl describe service <service-name>

D kubectl exec -it <pod-name> -- curl <service-name>:<port>

Using curl inside the pod tests if the service is reachable from that pod.

What might cause a service to be unreachable despite pods running?

A Network Policies blocking traffic

B Pods are in Running state

C Service has endpoints

D kubectl is installed

Network Policies can block traffic even if pods are running and endpoints exist.

Which command helps you see detailed info about a pod's status?

A kubectl describe pod <pod-name>

B kubectl get service <service-name>

C kubectl get nodes

D kubectl get endpoints <service-name>

The describe command shows detailed pod status and events.

Explain the steps you would take to debug why a Kubernetes service is not reachable from inside the cluster.

Think about checking pods, endpoints, connectivity tests, and network rules.

Describe how Network Policies can affect service connectivity in Kubernetes and how to verify if they are causing issues.

Focus on traffic rules and testing connectivity.