Thinking in Kubernetes

Here are the objects we're covering: Containers, Pods, ReplicaSets, Services, Secrets, ConfigMaps, Deployments, jobs, DaemonSets

Pods manage containers
ReplicaSets manage Pods
Services expose pod processes to the outside world
ConfigMaps and Secrets help you configure Pods
Labels are the plumbing that ties everything together (not covered in detail here)
Deployments manage the change from one set of replicasets/pods to another (e.g. for a software release)

Kubernetes Objects

represented as JSON or YAML files
you create these and then push them to the kubernetes API with kubectl
(or receive them as output from kubectl after it hits the kubernetes API for you)

Regardless of the type of object you're dealing with, the basic syntax is:

kubectl apply -f obj.yaml

You can interactively edit using

kubectl edit <resource-name> <obj-name>

This will:

download a yaml representation of the object using the kubernetes API
launch your $EDITOR on that textfile
re-upload your saved changed using the Kubernetes API, which will re-evaluate that object definition and make the necessary changes.

If you've got a resource file (manifest) handy:

kubectl delete -f obj.yaml

or any object in the kubernetes system with:

kubectl delete <resource-name> <obj-name>

Like folders, used to organize objects If you don't specify one with --namespace, kubectl uses the 'default' namespace

More permanent namespaces (modifies your kubernetes config file at $HOME/.kube/config) Useful if you're managing multiple kubernetes clusters

kubectl config set-context my-context --namespace=mystuff kubectl config use-context my-context