Working with Docker / OCI Containers using Podman

In this lecture, we will understand the difference between Virtualization and Containerization

In this lecture, we will understand how containers can help us solve common problems.

In this lecture, we will understand what is Docker and Podman

Here we will discuss about Linux Kernel Namespaces, CGroups and UnionFS

A short discussion on Container, Image and Registry

This is a guided exercise that demonstrates how to install Podman on CentOS Stream release 9

Now that we have everything setup, it’s time to get our hands dirty. In this section, you are going to run an Alpine Linux container (a lightweight Linux distribution) on your system and get a taste of the podman run command.

Podman allows you to save your containers as images. This is one way of converting and committing your container changes to a new image. podman commit command creates a new image from the container's changes. The new image will contain the contents of the container filesystem, excluding any data volumes.

A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using podman build users can create an automated build that executes several command-line instructions in succession. The podman build command builds an image from a Dockerfile.

One of the most challenging things about building images is keeping the image size down. Each instruction in the Dockerfile adds a layer to the image, and you need to remember to clean up any artifacts you don’t need before moving on to the next layer. To write a really efficient Dockerfile, you have traditionally needed to employ shell tricks and other logic to keep the layers as small as possible and to ensure that each layer has the artifacts it needs from the previous layer and nothing else. Multi-Stage build can help solve this problem.

Red Hat® Quay is a private container registry that stores, builds, and deploys container images. It analyzes your images for security vulnerabilities, identifying potential issues that can help you mitigate security risks. Additionally, it delivers georeplication and BitTorrent distribution to increase performance across distributed development sites and increase resiliency and redundancy for disaster recovery.

Podman uses two different means for its networking stack, depending on whether the container is rootless or rootfull. When rootfull, defined as being run by the root (or equivalent) user, Podman primarily relies on the containernetworking plugins project. When rootless, defined as being run by a regular user, Podman uses the slirp4netns project.

Data volumes are used to manage data with podman. A data volume is a specially-designated directory within one or more containers that bypasses the Union File System.