Using Buildah to build containers for Docker and Podman

One of my colleagues pointed me to an article on using Buildah to create container images: How rootless Buildah works: Building containers in unprivileged environments.

I decided to test it out! In this case, I just wanted to build a container using the shell script method described in the article, rather than using a Dockerfile. Although the rootless aspect is interesting to me, I believe that requires newer versions of Buildah than what is available by default on CentOS 7. A project for another day!

First, I needed a test case. I decided to use my NLTK chatbot container image, which can be found at:

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Docker versus Podman and iptables

I have recently been learning about podman, a tool for running containers that has a command syntax that matches Docker, but that does not require a Docker daemon and which does not require root privileges.

I ran into some unexpected problems publishing ports with Podman, which had to do with my default DROP policy on the iptables FORWARD chain. Below I will demonstrate some of the differences between Docker and Podman in terms of iptables changes, and provide a workaround for Podman.
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