https://youtu.be/oqWgMc9yYcc

Resources

1. Chapter 1 of the training course please refer to

Copy of #100DaysOfKubernetes

Main Node

Where does the orchestration come in?

• Managed by several operators and controllers — will look at operators and controllers later one. Operators make use of custom resources to manage an application and their components.
• "Each controller interrogates the kube-apiserver for a particular object state, modifying the object until the declared state matches the current state." In short, controllers are used to ensure a process is happening in the desired way.
• "The ReplicaSet is a controller which deploys and restarts containers, Docker by default, until the requested number of containers is running." In short, its purpose is to ensure a specific number of nodes are running

There are several other API objects which can be used to deloy pods. A DaemonSet will ensure that a single pod is deployed on every node. These are often used for logging and metrics pods. A StatefulSet can be used to deploy pods in a particular order, such that following pods are only deployed if previous pods report a ready status.

API objects can be used to know

• What containerized applications are running (and on which nodes)

• The resources available to those applications

• The policies around how those applications behave, such as restart policies, upgrades, and fault-tolerance

• kube-apiserver

• kube-scheduler

• etcd Database

• Other Agents

• There are several add-ons which have become essential to a typical production cluster, such as DNS services. Others are third-party solutions where Kubernetes has not yet developed a local component, such as cluster-level logging and resource monitoring.