Learn what is Kubernetes? what are its basic terms and definitions
Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.
The name Kubernetes originates from Greek, meaning helmsman or pilot. Google open-sourced the Kubernetes project in 2014. Kubernetes combines over 15 years of Google’s experience running production workloads at scale with best-of-breed ideas and practices from the community.
What can Kubernetes do? Why you need it?
Containers are a good way to bundle and run your applications. In a production environment, you need to manage the containers that run the applications and ensure that there is no downtime. For example, if a container goes down, another container needs to start. Wouldn’t it be easier if this behavior was handled by a system?
That’s how Kubernetes comes to the rescue! Kubernetes provides you with a framework to run distributed systems resiliently. It takes care of scaling and failover for your application, provides deployment patterns, and more. For example, Kubernetes can easily manage a canary deployment for your system.
What Kubernetes provide and how it is useful?
- Service discovery and load balancing
Kubernetes can expose a container using the DNS name or using its own IP address. If traffic to a container is high, Kubernetes is able to load balance and distribute the network traffic so that the deployment is stable.
- Storage orchestration
Kubernetes allows you to automatically mount a storage system of your choice, such as local storage, public cloud providers, and more.
- Automated rollouts and rollbacks
You can describe the desired state for your deployed containers using Kubernetes, and it can change the actual state to the desired state at a controlled rate. For example, you can automate Kubernetes to create new containers for your deployment, remove existing containers, and adopt all their resources to the new container.
- Automatic bin packing
You provide Kubernetes with a cluster of nodes that it can use to run containerized tasks. You tell Kubernetes how much CPU and memory (RAM) each container needs. Kubernetes can fit containers onto your nodes to make the best use of your resources.
Kubernetes restarts containers that fail, replaces containers, kills containers that don’t respond to your user-defined health check, and doesn’t advertise them to clients until they are ready to serve.
- Secret and configuration management
Kubernetes lets you store and manage sensitive information, such as passwords, OAuth tokens, and SSH keys. You can deploy and update secrets and application configuration without rebuilding your container images, and without exposing secrets in your stack configuration.
Kubernetes basic terms and definitions that you should know:
To begin understanding how to use K8S, we must understand the objects in the API. Basic K8S objects and several higher-level abstractions are known as controllers. These are the building block of your application lifecycle.
Basic objects include:
- Pod. A group of one or more containers.
- Service. An abstraction that defines a logical set of pods as well as the policy for accessing them.
- Volume. An abstraction that lets us persist data. (This is necessary because containers are ephemeral—meaning data is deleted when the container is deleted.)
- Namespace. A segment of the cluster dedicated to a certain purpose, for example, a certain project or team of devs.
Controllers, or higher-level abstractions, include:
- ReplicaSet (RS). Ensures the desired amount of pod is what’s running.
- Deployment. Offers declarative updates for pods an RS.
- StatefulSet. A workload API object that manages stateful applications, such as databases.
- DaemonSet. Ensures that all or some worker nodes run a copy of a pod. This is useful for daemon applications like Fluentd.
- Job. Creates one or more pods, runs a certain task(s) to completion, then deletes the pod(s).
We also reported that the Linux Foundation has tied up with Cloud Native Computing Foundation (CNCF) to announce a certification in the field of cloud-native computing. The new certification is called the Certified Kubernetes Security Specialist (CKS) and designed specifically for cloud-native professionals and will have a performance-based certification exam.
Linux Foundation says that the new CKS certification is being developed to enable cloud-native professionals to demonstrate their security skills to current and potential employers. The CKS exam will be available for enrollment in November 2020 and will cost $499.00 for training. More information about the exam and topics to be covered in it is available here. Those who intend to pursue the CKS but do not already hold a CKA certification may learn more about that exam here.
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