Update assignment.md

technical-writer/assignment.md

@@ -1,19 +1,108 @@
-# Debug Operations in Kubernetes
+# Debug Operations in Kubernetes with `kubectl`
 
-Kubernetes contains several commands, sometimes we can use these commands to do things. A good command to know is kubectl get pods which is used to get a list of all pods that are available and what their status is. Just rememember that when you use this command tat you may have to specify the `namespace`.
+One tool to debug Kubernetes operations is the `kubectl` command line interface (CLI). The `kubectl` CLI communicates with the Kubernetes application programming interface (API) server.
 
-```shell
-kubectl get pods --namespace 
+## Prerequisites
+
+- Install `kubectl`. Use a version of `kubectl` that is compatible with your Kubernetes cluster.
+  - Use the Kubernetes [Install Tools](https://kubernetes.io/docs/tasks/tools/) for additional guidance.
+- Configure the `$HOME/.kube/config` file to allow `kubectl` to communicate with your Kubernetes cluster.
+  - See [Kubeconfig](https://docs.spectrocloud.com/clusters/cluster-management/kubeconfig/).
+
+## Commands
+
+### `kubectl get`
+
+`kubectl get` provides a list of all resource objects within a namespace and their status.
+
+```console
+$ kubectl get pods
+NAME                                                  READY   STATUS    RESTARTS      AGE
+pod1                                                  1/1     Running   1 (24m ago)   2d23h
+pod2                                                  1/1     Running   2 (12m ago)   10d1h
+pod3                                                  1/1     Running   0             4d20h
+pod4                                                  1/1     Running   0             12m
+```
+
+A list of supported resources within the connected Kubernetes cluster is retrieved with the command `kubectl api-resources`. See X.
+
+> **_Note:_**
+When using any `kubectl` command with namespaced resources, the `default` namespace is used unless otherwise specified. To use a different namespace use the `--namespace` or `-n` command flags. Alternatively, retrieve objects across all namespaces with the flags `--all-namespaces` or `-A`. See X.
+
+```console
+$ kubectl get services --namespace myapp-namespace
+NAME                                TYPE           CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
+service1                            LoadBalancer   10.101.94.125    localhost     8000:32259/TCP   2d23h
+service2                            NodePort       10.101.105.247   <none>        6379/TCP         2d23h
+service3                            ClusterIP      10.106.49.233    <none>        8080/TCP         2d23h
 ```
 
-Speaking of commands, kubectl is the CLI that is used to interact with k8s. The kubectl cli commmunicates with the kubernettes API server.  Another command that is helpful is the kubectl logs command. In Azure, kubernetess is available, just like other cloud providers. This command is used to retrive the logs of a specific pod - do use this when you have to review logs or need to debug a container. Another we will dicuss is the `kubectl exec` command. A command that we can use to debug a container from the inside or to explore the the enviroment of the container itself.  I recommend when debugging you start with kubectl get pods, then `kubectl logs` and lastly we can use `kubectl exec` to explore the inside of the container and review other log files or configurations. 
+### `kubectl describe`
+
+To retrieve all metadata about a single Kubernetes object, use the `kubectl describe` command.
+
+```console
+$ kubectl describe secret my-secret
+Name:         my-secret
+Namespace:    default
+Labels:       app.kubernetes.io/name=myapp
+              app.kubernetes.io/managed-by=Helm
+Annotations:  meta.helm.sh/release-name: myapp
+              meta.helm.sh/release-namespace: default
+
+Type:  Opaque
+
+Data
+====
+mysecret-password:       10 bytes
+```
 
-**Note:** The command `kubectl debug` is another option to considering when debugging a container. This command can be used to create a clone of a pod that does not terminate if an error is experienced inside the container. 
+### `kubectl logs`
+
+Use `kubectl logs` to retrieve the logs of a specific container. If multiple containers exist within the pod, use the command flags `--container` or `-c` to use a specific container. Use the `-f` to stream the logs rather than retrieving them once.
+
+```console
+kubectl logs <pod-name> [--container <container-name>]
+```
+
+> **_Note:_**
+`kubectl logs` relies on the container's logs streaming to `STDOUT` and `STDERR`.
+
+### `kubectl exec`
+
+Use the `kubectl exec` command runs another command inside a container or to explore the the environment of the container. If multiple containers exist within the pod, use the command flags `--container` or `-c` to use a specific container. The command to run inside the container follows the final instance of `--`.
+
+```console
+$ kubectl exec <pod-name> -- ping -c 4 spectrocloud.com
+PING spectrocloud.com (10.3.50.11): 56 data bytes
+64 bytes from 10.3.50.11: seq=0 ttl=63 time=46.389 ms
+64 bytes from 10.3.50.11: seq=1 ttl=63 time=44.176 ms
+64 bytes from 10.3.50.11: seq=2 ttl=63 time=43.195 ms
+64 bytes from 10.3.50.11: seq=3 ttl=63 time=43.454 ms
+
+--- spectrocloud.com ping statistics ---
+4 packets transmitted, 4 packets received, 0% packet loss
+round-trip min/avg/max = 43.195/44.303/46.389 m
+```
+
+### `kubectl debug`
+
+Use the `kubectl debug` command to create temporary objects or make temporary changes to debug operations. For example, this command can be used to create a debugging container within a pod.
+
+```console
+kubectl debug <pod-name> -it --image=busybox
+```
 
+## Recommended Process
 
+There are many methods to debugging. A common approach is to work "top-down". An example is below to determine the root cause of the failure of an application inside of a container.
 
-# References
+- Use `kubectl get` to identify the status of a pod.
+- Use `kubectl describe` to identify the status of a container with that pod.
+- Use `kubectl logs` to look at the logs inside of the container.
+- Use `kubectl exec` or `kubectl debug` to make changes within the container.
 
-- https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands#-strong-getting-started-strong-
+## References
 
-- [What is Kubernetes](https://kubernetes.io/docs/concepts/overview/)
+- [Monitoring, Logging, and Debugging](https://kubernetes.io/docs/tasks/debug/)
+- [kubectl reference](https://kubernetes.io/docs/reference/kubectl/generated/).