The Big Picture - kubernetes/kubernetes - Container Diff

Kubernetes is an open-source platform designed to automate deploying, scaling, and managing containerized applications. At the heart of Kubernetes are containers, which are the portable, lightweight units of software that encapsulate an application and its dependencies. However, it’s essential to understand the differences between containers and their images.

Containers vs Images

Containers are the runtime instances of images. An image is a static snapshot of a container’s file system, including the application code, libraries, and dependencies. When you run a container, a new instance is created from the image, and the container runtime (such as Docker or containerd) starts the container, allocating system resources and networking.

Changing the Container Runtime

Kubernetes supports multiple container runtimes, including Docker and containerd. If you need to change the container runtime on a node, you can follow the instructions in the official Kubernetes documentation.

Kubernetes Components

Kubernetes consists of various components, including:

  • Pods: The smallest deployable unit in the Kubernetes object model that you create or deploy. A Pod represents a running process on your cluster and can contain one or more containers.
  • Deployments: Used to create, update, and manage replicas of your Pods.
  • Services: An abstract way to expose an application running on a set of Pods as a network service.
  • Persistent Volumes (PV) and Persistent Volume Claims (PVC): Used to store and manage data that needs to be accessed by multiple containers or across container restarts.

Ephemeral Containers

Ephemeral containers are a special type of container that runs temporarily in an existing Pod to accomplish user-initiated actions such as troubleshooting. They are not intended for building applications but for inspecting the state of an existing Pod.

Kubernetes Cheat Sheet

To help you get started with Kubernetes, you can download the Kubernetes cheat sheet from Opensource.com. It covers essential Kubernetes concepts and commands.

Connecting Kubernetes and Docker

Although Kubernetes runs on top of Docker, it’s important to note that containers running on Docker and containers running inside of a Kubernetes Pod are isolated from each other. However, you can still interact with Docker containers when working with Kubernetes. For more information, you can refer to Nikhil Chawla’s blog post.

Monitoring Kubernetes with Grafana

To monitor your Kubernetes clusters and applications, you can use Grafana, an open-source platform for data visualization and monitoring. Grafana supports various Kubernetes metrics, such as CPU and memory usage, container restarts, and network traffic. For more information, you can refer to Grafana’s Kubernetes monitoring documentation.

Conclusion

Understanding the differences between containers and images, as well as the various components of Kubernetes, is essential for effectively managing and deploying containerized applications. By using the resources mentioned in this documentation, you’ll be well on your way to mastering Kubernetes and container diff.

References