Introduction to Kubernetes

What is Kubernetes?

Kubernetes is an open-source container orchestration solution that streamlines container deployment, scalability, and load balancing. It supports a variety of platforms, including on-premises bare metal, OpenStack, and major public clouds such as Google, Azure, and AWS.

Why use Kubernetes?

Microservices provide higher adaptability than monolithic services, which is pushing their acceptance in the rapidly evolving IT world. Deploying applications in containers offers robustness, with Kubernetes managing containers for zero downtime, making it necessary for both micro and monolithic apps.

Kubernetes Features

• Automated Scheduling​
• Self-Healing Capabilities​
• Automated rollouts & rollback​
• Horizontal Scaling & Load Balancing​
• Offers enterprise-ready features​
• Application-centric management​
• Auto-scalable infrastructure​

Kubernetes Disadvantages

• Kubernetes can be an overkill for simple applications​
• Kubernetes is very complex and can reduce productivity​
• The transition to Kubernetes can be complicated​
• Kubernetes control plane only supports the Linux platform
• Only Kubernetes V1.14 is supported by Windows Server 2019
• Supports clusters with up to 5000 nodes
• Supports 150000 total pods
• Supports 300000 total containers
• Supports 100 pods per node
• 2 GiB or more of RAM per machine for Kubernetes 
• At least 2 CPUs on the machine that you use as a control-plane node
• Kubernetes allows administrators to set quotas, in namespaces

Object types in Kubernetes

Kubernetes supports the following key objects:

• Pod
• Node
• Service
• Replica Set
• Namespace
• Replication Controller
• Deployments
• Volume
• Secret
• Kubectl

Kubernetes Alternatives

• Rancher
• Nomad
• Docker Swarm
• Cloud Foundry
• AWS Fargate
• Apache Mesos
• OpenStack
• Docker Compose

Kubernetes-master supports the platform

• Ubuntu 16.04+
• Debian 9+
• CentOS 7
• Red Hat Enterprise Linux (RHEL) 7
• Fedora 25+
• HypriotOS v1.0.1+
• Container Linux

Kubernetes Architecture

• Kubernetes uses a client-server architecture, with a master on one system and nodes on other Linux machines.
• In a master-slave system, the master manages Docker containers across several nodes.
• A Kubernetes cluster consists of master and worker nodes.
• The Kubernetes master helps developers as they deploy apps in Docker containers.

Kubernetes Applications

• Microservice Architecture.
• Cloud-Based Development.
• Continuous integration & delivery.
• Hybrid and multi-cloud deployments.
• High-performance computing.
• Edge computing.