Kubernetes Cheatsheet

Kubernetes is a powerful container orchestration engine. It became one of the most favorite platforms due to its rich ecosystem, diverse instruments and many other benefits it offers. Kubernetes gives you features like service-discovery, fault-tolerance, inter-service communication, load-balancing, auto-scaling, etc out of the box. But Kubernetes is still incredibly complex; it takes time and patience to learn.

At first glance there is nothing hard about learning to use Kubernetes. You need to know fundamentals about Kubernetes Components, such as control plane and worker nodes. Then you learn the most common resource types and how to use kubectl to perform different operations for Pods, Deployments, Services and a few other resources. That is the foundation that you can gain fairly quickly.

What makes it complicated is that you also need to learn all of the auxillary tools required to support the platform (Prometheus, Logging, Cluster management, Troubleshooting, Helm charts, CI/CD, GitOps, Infrastructure as a Code, service-meshes etc), without these you are flying blind. This is a huge learning curve, and it is not something that is easy to learn.

Cheatsheet

Despite all the complexity, there are common routines that every developer wants to accomplish within Kubernetes. Similarly, there are common approaches and tooling, such as kubectl and Helm. These command line tools are surprisingly approachable and straightforward. Below I listed the most popular commands/tasks that will make your daily developer’s duties a little bit easier.

Switch context

A context is a configuration that you use to connect to a certain cluster. For example, you can connect to a minikube cluster running your machine (local dev environment) or connect to a continuos integration cluster running on a remote machine (test environment).

The following command can be used to view all the contexts:

kubectl config get-contexts

View current context:

kubectl config current-context

Switch to the desired context:

kubectl config use-context "arn:aws:eks:<aws-region>:<id>:cluster/test-eks"

List pods

Use the following command to retrieve a list of pods in given namespace:

kubectl get pods -n "<namespace>"

To retrieve a list of pods in all namespaces:

kubectl get pods --all-namespaces

Get pod logs

Get the logs for the last 15 minutes for a pod:

kubectl logs --since=15m "<pod_name>"

Get resource usage

Note that the following command requires the Metrics API installed.

Display resource usage (CPU/RAM) of pdos per container:

kubectl top pods -n "<namespace>" --containers

Get metrics for the node:

kubectl top node 

Describe services

Display the detailed information about the service in the given namespace:

kubectl describe services "<service_name>" -n "<namespace>"

Extract the IP address of the service:

$ipAddress = (kubectl describe services "<service_name>" -n "<namespace>" | Select-String "IP" |)
Write-Host $ipAddress

Secrets

Create a ssl certificate secret in the given namespace:

kubectl create secret tls "<secret_name>" -n "<namespace>" --key ./key.pem --cert ./certificate.crt

View the secrets:

kubectl get "secrets/<secret_name>" -n "<namespace>"

Helm charts

To list all the Helm chart dependencies:

helm dependency list "<chart_name>"

To upgrade the release with all dependencies, run the command as follows:

helm upgrade "<chart_name>" -i "<release_name>" -n "<namespace>" --set tags.all=enabled

To upgrade the release without certain dependencies, for example exclude sub-charts tagged as frontend, run the command as follows:

helm upgrade "<chart_name>" -i "<release_name>" -n "<namespace>" --set tags.frontend=false

To get the values for a named release:

helm get values ringbax -n "<namespace>"

To list all installed charts:

helm ls -n "<namespace>"

Redeploy pods

To shut down and restart each container in your deployment one by one, run this command:

kubectl rollout restart deploy -n "<namespace>"

To remove all the pods in a given namespace:

kubectl delete pod --all -n "<namespace>"

Next steps

Consider this list a starting point for your Kubernetes cheatsheet. These commands are simple, and cover typical operations, hence are good to have for any developer working with Kubernetes.

• Learn more about Kubernetes
• Learn about Helm package manager for Kubernetes
• minikube for local development
• k9s command line interface for an overview of your cluster resources