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Frequently Asked Questions

How do I shut everything down and restart from scratch?

You can use kubectl delete -f to remove the resources specified in a YAML file. So for the resources in this assignment:

kubectl delete -f proxy/k8
kubectl delete -f GiftcardSite/k8
kubectl delete -f db/k8

Note that removing pods will not remove their persistent storage, and even deleting the persistent volume and persistent volume claim won't do it. To actually delete the data, you'll need to use minikube ssh to get access to the host container, and then remove the files there.

For example, to get rid of the persistent volume associated with the database (mysql-pv), you would do:

youruser@$ minikube ssh
docker@minikube:~$ sudo rm -rf /data/mysql-pv
docker@minikube:~$ logout

You can find out where the data for a persistent volume is located by looking at its hostPath in the PersistentVolume YAML file:

  hostPath:
    path: /data/mysql-pv

How do I see what's going wrong?

Start by looking at what pods are running, and their states:

kubectl get pods

If a pod is in a state other than "Running", you can get more details about it:

kubectl describe pod <pod_name>

You can also ask for logs from a pod:

kubectl logs <pod_name>

Finally, it might be helpful to run a shell inside the pod's container so that you can run commands and see what's going on. You can do that by running:

kubectl exec --stdin --tty <pod_name> -- bash

Some pods (e.g., the GiftcardSite pod) don't have bash installed, so you'll need to use sh instead.

Why can't kubectl find my Docker image?

The most common reason is that you forgot to run eval $(minikube docker-env) before running docker build. This points the Docker client at the minikube Docker daemon.

Another common mistake is specifying the image version in the YAML file as latest (e.g., my_image:latest). This will make kubectl try to fetch the image from a remote repository, which will fail if it's an image you've created locally. You can override this behavior either by removing the :latest tag, or by adding imagePullPolicy: Never to the YAML file.

How can I open the web interface for a service?

You can find out what services are available by doing minikube service list:

caterina:k8s moyix$ minikube service list 
|----------------------|-------------------------------|--------------|-----|
|      NAMESPACE       |             NAME              | TARGET PORT  | URL |
|----------------------|-------------------------------|--------------|-----|
| default              | assignment3-django-service    |         8000 |     |
| default              | kubernetes                    | No node port |
| default              | mysql-service                 | No node port |
| default              | prometheus-alertmanager       | No node port |
| default              | prometheus-kube-state-metrics | No node port |
| default              | prometheus-node-exporter      | No node port |
| default              | prometheus-pushgateway        | No node port |
| default              | prometheus-server             | No node port |
| default              | proxy-service                 |         8080 |     |
| kube-system          | kube-dns                      | No node port |
| kubernetes-dashboard | dashboard-metrics-scraper     | No node port |
| kubernetes-dashboard | kubernetes-dashboard          | No node port |
|----------------------|-------------------------------|--------------|-----|

Then pick a service and use minikube service <name> to open a browser to that service's URL:

caterina:k8s moyix$ minikube service prometheus-server
|-----------|-------------------|-------------|--------------|
| NAMESPACE |       NAME        | TARGET PORT |     URL      |
|-----------|-------------------|-------------|--------------|
| default   | prometheus-server |             | No node port |
|-----------|-------------------|-------------|--------------|
😿  service default/prometheus-server has no node port
🏃  Starting tunnel for service prometheus-server.
|-----------|-------------------|-------------|------------------------|
| NAMESPACE |       NAME        | TARGET PORT |          URL           |
|-----------|-------------------|-------------|------------------------|
| default   | prometheus-server |             | http://127.0.0.1:61867 |
|-----------|-------------------|-------------|------------------------|
🎉  Opening service default/prometheus-server in default browser...
❗  Because you are using a Docker driver on darwin, the terminal needs to be open to run it.