Basic image building with Podman

A container's OCI image is a set of immutable layers stacked together with a copy-on-write logic. When an image is built, all the layers are created in a precise order and then pushed to the container registry, which stores our layers as tar-based archives along with additional image metadata.

As we learned in the OCI Images section of Chapter 2, Comparing Podman and Docker, these manifests are necessary to correctly reassemble the image layers (the image manifest and the image index) and to pass runtime configurations to the container engine (the image configuration).

Before proceeding with the basic examples of image builds with Podman, we need to understand how image builds generally work to grasp the simple but very smart key concepts that lay beneath.

Builds under the hood

Container images can be built in different ways, but the most common approach, probably one of the keys to the huge success of containers, is based on Dockerfiles...