Installation on Linux via Podman

Overview

This guide covers the installation of CAST Imaging on Linux using Podman . It is intended for:

Podman running on Linux operating systems
new installations (for updates to existing installations, see In-place component update)

The installation package com.castsoftware.imaging.all.docker includes an installation script and configuration files. All images are pulled direct from https://hub.docker.com during the installation. Alternatively you can alternatively configure the installer to function in “offline mode”.

The general installation process for CAST Imaging for Podman on Linux is identical to the installation process for Docker on Linux (see Installation on Linux via Docker). Please familiarize yourself with those instructions before proceeding.

Requirements

Obtain the installation media

See Obtain the installation media.

Podman installation

CAST assumes that Podman is already installed on your target Linux machine(s): see https://podman.io/docs/installation#installing-on-linux .

Installation steps

Step 1 - Install podman-docker

podman-docker is a compatibility package that allows you to use Podman as a drop-in replacement for Docker: it creates a symbolic link from the docker command to podman. This means when you type docker run, docker build, or any other Docker command, you’re actually running Podman instead. This is required since the CAST Imaging installation script uses docker commands. You can install it as follows:

# Fedora/RHEL
$ sudo dnf install podman-docker

# Debian/Ubuntu
$ sudo apt install podman-docker

Check that the package has been correctly installed using a Docker command such as:

$ docker --version

You should see a response similar to:

Emulate Docker CLI using podman

Step 2 - Install a compose provider

CAST Imaging’s installer relies on docker compose to read and start containers and setup the required networks, volumes and file shares. Choose one of the following options:

Option A: Install podman-compose (recommended)

Available through some package managers, or install via Python 3 and pip.
See the official documentation .
Ensure it’s installed globally to make it available to all users (including root)
Check it’s installed using the following command:

$ which podman-compose

Option B: Install legacy standalone docker-compose

This is the legacy 1.x release and is available in most package managers, for example:

# Fedora/RHEL
$ sudo dnf install docker-compose

# Debian/Ubuntu
$ sudo apt install docker-compose

Step 3 - Update registries.conf

Configure Podman to use Docker Hub as the default container registry. Create (if it does not exist) or update the following file:

$HOME/.config/containers/registries.conf

Add the following line to the file:

unqualified-search-registries = ["docker.io"].

Why is this needed: Podman does not default to Docker Hub (where CAST Imaging images are stored) and expects fully qualified image names (e.g.: registry.com/namespace/imagename). This setting allows Podman to default to Docker’s container registry.

Step 4 - Update containers.conf

Configure Podman to recognize your compose provider installed previously. First Find your compose path (either podman-compose or docker-compose) using:

$ which podman-compose
# or
$ which docker-compose

Edit the containers.conf file using a text editor such as vi or nano(adapt the path to match your chosen compose provider):

/usr/share/containers/containers.conf

Update the compose_providers property to point to the relevant provider executable (the example below shows podman-compose):

compose_providers=["/usr/local/bin/podman-compose"]

Step 5 - Create a docker-compose wrapper

Create a wrapper script named docker-compose in:

$ sudo nano /usr/local/bin/docker-compose

Add the following content:

#!/bin/sh
podman compose "$@"

Make it executable:

chmod +x /usr/local/bin/docker-compose

Step 6 - Install CAST Imaging

Follow the instructions provided in Installation on Linux via Docker to complete the installation for Podman. Ensure you run the installation with the dedicated Podman installation script:

cast-imaging-install-podman.sh