Kubernetes

Kubernetes (K8s) is an open-source system for automating deployment, scaling, and management of containerized applications.

More information on Kubernetes here: Kubernetes

Kubernetes topics

• Building a Kubernetes Cluster
• Deploy a Kubernetes Cluster with Kubespray
• Managing applications with Kubernetes
• Persistent Volumes in Kubernetes
• Share data using Manila
• Minikube
• Deploy BinderHub on Kubernetes
• Deploy Kubernetes and JupyterHub with GPU support
• Using Cacao on Jetstream2 for Kubernetes

Third Party Kubernetes topics

• Deploy JupyterHub
• Update Openstack credentials in Kubernetes, useful if the Application Credential generated for Kubernetes has expired.
• Quickly scaling a Kubernetes cluster on Jetstream using shelving

---

Some K8s basics :

1. A Pod is the smallest deployable unit of Kubernetes. A Pod can contain one or more containers on a single IP address (internal). Containers within a pod can communicate with each other. Pods are run on Nodes.
2. A Node is a physical or virtual machine and it’s components include kubelet, kube-proxy and Container run-time.
   • Kubelet is the Node agent that manages containers created by Kubernetes.
   • Kube-proxy is used by Service to run a network proxy on each Node.
   • Container runtime is the software responsible for running containers. Ex: Docker, containerd, and CRI-O.
3. Service allows the use of a stable network address for an application, including a persistent ip address and a local DNS entry within the cluster. Service also acts as a load-balancer across all pods allowing the addition removal of pods from a deployment.
4. ReplicaSet is a convenient way to build multiple pods at once.
5. Deployment provides declarative updates for Pods and ReplicaSets (rolling updates)
6. Control Pane is a node that controls/manages worker nodes. The components of the Control Pane are the API Server, the cluster store, the controller manager, and the scheduler.
   • API server – All communication between the various Kubernetes components must go through the API server
   • Cluster Store or etcd – Persistently stores the cluster’s configuration, state, and metadata.
   • The Controller Manager runs controller processes that monitor and respond to controller events. Some examples of control loops include; node controller, job controller, end point controller, and replication controller.
   • The Scheduler assigns pods to nodes.