Kubernetes is an open source tool for managing, automating deployment, scaling of containerized application. Also known as an orchestration tool for container workloads.
A set of APIs that runs on top of Docker (you still can use another container runtime e.g. containerd). It's just a series of containers that manages those APIs to manage the multinode system.
Kube control: CLI to manage containers across servers with k8s
kubectl
How do you get it?
Usually from a cloud vendor that provides K8s as a service (APIs and GUIs). Other vendors package their own version of K8s as "distributions" similar as Linux distributions. But they are fundamentally the same, based on the pure open-source K8s.
Why you may need orchestration?
- Many people already are just running their containers with
docker runand adding load balancing, auto-scaling groups and many other things to build a similar orchestration solution. - It depends of
how fast your applications need to changeandhow many server you might need - If you don't change you applicaitons very often (once a month or less), orchestration might not be necessary.
Which orchestrator to choose?
- Swarm: Easier to deploy/manage.
- K8s: Hybrid can be run in multiple clouds or on-premises. Customizable and flexible. Wider adoption and support.
- ECS (AWS legacy solution before K8s): AWS specific offering. ...
Which distribution are you going to use?
- EKS
- Rancher
- OpenShift (RedHat)
- Canonical K8s
- PKS (VMWare)
- Raw Open Source K8s: https://github.com/kubernetes/kubernetes ...
Vendors products usually are just one version outdated, but they try to stay updated. Vendor solutions have custom authentication, custom web admin, custom networking, etc.
More Kubernetes Certified Distributions
Running first pod with k8s. This only creates a pod named my-nginx using nginx docker image.
kubectl run my-nginx --image nginx
To see the pods:
kubectl get pods
To see everything (including services):
kubectl get all
To delete a pod:
kubectl delete pod my-nginx