In this hands-on lab, we will briefly discuss what I typically use for debugging Kubernetes apps. I hope you will find it helpful too.

Lab Setup

You can start the lab setup by clicking on the Lab Setup button on the right side of the screen. Please note that there are app-specific URLs exposed specifically for the hands-on lab purpose.

Our lab has been set up with all necessary tools like base OS (Ubuntu), and developer tools like Git, Vim, wget, and others.

Exploring different ways to debug Kubernetes apps

In this section, we will be going through some of the ways like kubectl exec, sharing namespaces, and ephemeral containers to debug k8s applications.

Using plain old “exec”

kubectl apply -f exec-demo.yaml

kubectl get pods

kubectl exec -it -c nginx exec-demo -- ls

This approach will not work for environments where exec is disabled or for container images without a shell.

Let’s look at other approaches.

Using a sidecar

Enable process namespace sharing so that you can view processes in the app container from your debug container. You’ll generally need this for debugging.

• An example POD YAML using a sidecar image with network debugging tools.

kubectl apply -f pod.yaml

kubectl get pods

Using ephemeral containers

This is the latest Kubernetes feature and the most preferred.

You can create a debug container on the fly without pre-provisioning a sidecar. More details are available in the official documentation.

• Let’s see this in action. In the following example, I will create a debug container with perf tools.

kubectl apply -f nginx-pod.yaml

kubectl get pods

• Now I will create an ephemeral container by using kubectl debug

kubectl debug --image=quay.io/bpradipt/perf-amd64 -it --share-processes=true nginx-pod -- /bin/bash

Now you can perform your debugging tasks.

If you are wondering what’s happening behind the scenes, then the best place to look at is the POD spec — kubectl get pod nginx -o yaml

kubectl get pod nginx-pod -o yaml

You’ll see a new section added for ephemeral containers, as shown below:

• You can also create an entirely new debug POD as shown below:

kubectl debug --image=quay.io/bpradipt/perf-amd64 -it --share-processes=true --copy-to=debug-nginx nginx-pod -- /bin/bash

You’ll see a new debug POD created.

kubectl get pods

  I’m sure you’ll find ephemeral containers handy for debugging.

Conclusion

In this hands-on lab, we have explored different ways to debug the Kubernetes applications and the most efficient way is to use ephemeral containers for it.