Containerisation cheat-sheet

A list of useful Docker, Kubernetes and Helm commands

Basic Docker container management

• $ docker images - list locally cached images
• $ docker container ls - list running containers
• $ docker container stop containername - stop a running container
• $ docker container rm containername - remove a running container

Local Docker Registry

• $ docker run --detach --publish 5000:5000 --restart=always --name=registry registry:2 - run a local registry in the background
  The first port number refers to the local host, the second is the port within the container.
• $ docker tag imagename localhost:5000/myimagename - To push to a particular registry, first tag the image with the first part as hostname:port.
• $ docker push localhost:5000/myimagename - push myimagename from the local docker cache to the local registry
• $ docker pull localhost:5000/myimagename - pull myimagename from the local registry to the local docker cache

Kubernetes

The official cheat-sheet is pretty detailed, the shortlist below are my "beginners basics":

• $ kubectl version
• $ kubectl get nodes
• $ kubectl config get-contexts
• $ kubectl config current-context
• $ kubectl config use-context
• $ kubectl config view
• $ kubectl get deployments
• $ kubectl delete deployment name
• $ kubectl get pods [-o wide|yaml|json|go-template=] - list deployed pod names
• $ kubectl get pod --watch pod-name - follow pod status changes
• $ kubectl describe pod/pod-name - print detailed pod status and event transitions - useful for start-up diagnostics
• $ kubectl delete pod/pod-name
• $ kubectl get services
• $ kubectl describe service name
• $ kubectl delete service -l run=name
• $ kubectl logs pod-name - print pod application logs
• $ kubectl exec -ti pod-name -- bash
• $ kubectl exec -ti pod-name -- curl localhost:8080

Helm

Helm is an 'orchestration' service. It co-ordinates all of those separate Kubernetes configurations that are required to set up your application. Essentially it allows you to write Kubernetes config files as templates, extracting the variables to a top-level 'values.yaml' file, supporting a level of re-use and abstracting away some of Kubernetes' complexity. You must still learn the Kubernetes API though, and now also some {{ Go }} syntax too...

• $ helm list - list deployments
• $ helm install [--debug] [--dry-run] chartdir - deploy the given chart to the cluster
• $ helm delete ... - opposite of install
• $ helm status ... - print deployment status

YAML

Of course, you also need to learn YAML syntax. This cheat-sheet is the most helpful I've found so far. Scroll down to the Examples section.
The YAML spec website is a daunting place to start for something essentially so simple, but it does include a short refcard which may become useful once you know what it all means.