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5 posts tagged with "overview"

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· 3 min read

The storage management system​

Kubernetes Volume

Review previous parts of this series for better understanding:

This is the sixth part of the Kubernetes series. In this part I will try to add more insights into Kubernetes Volume

Volume

Volumeis simply an abstraction of data in the form of file and directory within a Pod. It exists as long as its Pod exists.

The lifecycle of a Volume is tied to the lifecycle of the Pod, but not to that of a Container. If a container within a Pod dies, the Volume persists and the newly launched container will be able to mount the same Volume and access its data. When a Pod gets restarted or dies, so do its Volumes, although if the Volumes consist of cloud block storage, they will simply be unmounted with data still accessible by future Pods.

· 4 min read

The brain of the system that keeps track of all the other parts.​

Kubernetes Controller Review previous parts of this series for better understanding:

This is fifth part of the Kubernetes series. In this part I will try to add more insights into Kubernetes Controller.

What is a Controller in Kubernetes?

A Controller is a non-terminating loop that regulates the state of a system. It watches the state of the cluster, then make or request changes where needed. Each controller tries to move the current cluster state closer to the desired state. There are different types of controllers for specific purposes.

Kubernetes Control Plane

Kubernetes Control Plane is a collection of the Controllers. kube-apiserver, kube-controller-manager and kube-scheduler are the three critical processes that makes up the control plane. Nodes that runs these processes are called Master Node which are replicated for availability and redundancy.

· 3 min read

An important component that manages routes and containers.​

Kubernetes Services

Review previous parts of this series for better understanding:

This is fourth part of the Kubernetes series. In this part I will try to add more insights into Kubernetes Service.

What is a Service in Kubernetes?

A Service groups Pods together that perform the same function as a single entity. It keeps track of containers in the Pods and routes to the containers for internal and external access. A Service’s IP address remains stable regardless of changes to the Pods it routes to, which makes it easy to gain discoverability and can simplify containers designs. By default, Services are only available using an internally routable IP address, they can be made available outside of the Cluster by choosing one of several strategies.

Types Of Services

There are 4 types of Services, specified by the type field in the Service Configuration File:

· 2 min read

Essential building blocks of the complicated system.​

Kubernetes Object

Review Kuberenetes Overview

This is the second part of the Kubernetes series. In this part I will try to add more insights into Kubenetes Objects.

Kubernetes Objects

Kubernetes Objects are persistent entities in Kubernetes. All objects have unique names that allows idempotent creation and retrieval. These objects are stored in etcddatabase as a key-value pair. Objects can categorized as the Basic Objects which determines the deployed containerized application's workloads, their associated network and disk resources, and Higher Level Objects which are build upon the basic objects to provide additional functionality and convenience features to manage the workloads. Higher level objects have a long-running service-like lifecycle, except Jobs.

  • Basic Objects: Pod, Service, Volume and Namespace
  • Higher Level Objects: Replication Controllers, Replication Sets, Deployments, Stateful Sets, Daemon Sets Jobs and Cron Jobs

Every Kubernetes Object definition is a YAML file that contains at least the following items:

  • apiVersion: The version of the Kubernetes API that the definition belongs to.
  • kind: The Kubernetes object this file represents. For example, a pod or service.
  • metadata: This contains the name of the object along with any labels that you may wish to apply to it.
  • spec: This contains a specific configuration depending on the kind of object you are creating, such as the container image or the ports on which the container will be accessible from.

· 2 min read

The easiest way to visualize components and how they work.​

Kubernetes Overview

This is the first part of the Kubernetes series. In this part I will surficially touch things realted to Kubenetes quickly.

Evolution Of Hosting

Traditionally, applications used to run on one or more Physical Servers. The main drawback was that they did not scale well as resources were not utilized to the maximum. Virtual Machines solved the problem and enhanced security of applications by providing isolated environments which enabled adoption of distributed systems tremendously. Then, with the large number of applications running in the Virtual Machines, maintenance started to become cumbersome. Now there are Containerization technologies which solved the problems of Virtual Machines by abstracting and enhancing their entire functionalities. Kubernetes has made it extremely easy to manage the Containerized Applications.

Kubernetes Architecture