An introduction to containers

Understand what containers are and how they are used by IBM® z/OS® Connect.

Containers and container concepts

If you are new to container concepts, the following IBM Cloud Education resources provide an explanation of containers, container orchestration, and cloud native development. These concepts are vital for working with the OpenAPI 3 support of z/OS Connect.
Containerization
The following article explores the history of containerization, the benefits and advantages of using the technology, and how it relates to virtualization:
The benefits of containers
The following articles look at the importance of containers in cloud computing, highlighting the core benefits, and tour the emerging ecosystem of related technologies:
Cloud native applications
The following article explores cloud native applications and how they drive innovation and speed within your enterprise:

An introduction to Podman

A launch icon to indicate a link opens a new tab or window. Podman is a daemonless, open source, Linux native tool that is designed to make it easy to find, run, build, share, and deploy applications by using Open Containers Initiative (OCI) containers and container images. Podman provides a command-line interface (CLI) similar to Docker. Podman, like other common container engines (Docker, CRI-O, containerd), relies on an OCI-compliant container runtime (runc, crun, runv) to interface with the operating system and create the running containers. This makes the running containers that are created by Podman almost indistinguishable from those created by any other common container engine.

Containers under the control of Podman can either be run by root or by a nonprivileged user. Podman manages the entire container ecosystem that includes pods, containers, container images, and container volumes by using the libpod library. Podman specializes in all of the commands and functions that help you to maintain and modify OCI container images, such as pulling and tagging. It allows you to create, run, and maintain those containers and container images in a production environment.

Podman (Pod Manager) is a fully featured container engine that is a simple daemonless tool. Podman provides a CLI comparable to Docker that eases the transition from other container engines and allows the management of pods, containers, and images. Most Podman commands can be run as a regular user, without requiring extra privileges.

Podman uses Buildah internally to create container images. Both tools share image (not container) storage, hence each can use or manipulate images (but not containers) created by the other.

For more information, see A launch icon to indicate a link opens a new tab or window. What is Podman?

An introduction to Docker

Docker is an open source platform for building, deploying, and managing containerized applications. In this documentation, the quick start tutorials use Docker Desktop to run the z/OS Connect Designer image.

What is Docker?
If you are new to Docker, the IBM Cloud Education article A launch icon to indicate a link opens a new tab or window. What is Docker? explains why it has become so widely adopted. The section A launch icon to indicate a link opens a new tab or window. Docker tools and terms is of special interest to z/OS Connect users.

IBM z/OS Connect as a containerized application

Figure 1 illustrates the structure of a IBM z/OS Connect container image. The layers of a container image can be customized to suit your requirements.
Figure 1. A typical container image
A typical container image
What is a layer?
  • Each layer is an image itself that stores the changes compared to the image it is based on.
  • Layers exist to save on computational effort and time when building images.
  • Layers are used to avoid transferring existing information and skip the build steps that have not changed.
For more information, see A launch icon to indicate a link opens a new tab or window. Images and layers in the Docker documentation.