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Docker has two main building blocks: Docker CLI and Docker Daemon.
Docker uses its Docker Engine REST API to interact with the Docker daemon, accessed via HTTP protocol.
Docker CLI:
It is the Docker command line client for interacting with the Docker daemon.
It is what you use when you run any Docker command.
All container tools like Docker come with an image-based deployment model.
This model simplifies sharing an software or set of services across multiple environments.
Additionally, Docker helps automate the deployment of applications within a container environment.
It was developed by Red Hat and originally intended for its enterprise Linux 8.
It is used for container management and acts as the official successor to Docker.
It manages the entire container ecosystem using thelibpod library.
The libpod library supports multiple methods to upload images securely, including trust and image verification.
In very small and manageable environments, Podman can even serve as a precursor to Kubernetes.
Ambitious container users can already enjoy the next level with the pods.
The construction and operation of a Kubernetes cluster are no longer necessary.
In the simplest case, newly designed pods can be tested and improved in individual operations.
Even a subsequent transfer to Kubernetes is possible.
The commandpodman generate kubesupplies the corresponding configuration files.
These then serve one-to-one as input for the Kubernetes tool kubectl.
Podman vs Docker: Differences
Docker has quickly established itself as the hobbyhorse for managing containers.
Moreover, Docker isno longer supportedas a container for Kubernetes.
The first distinction is apparent when you first use it.
So there is no background process, and the utility is only executed when needed.
Podman does not require a background process due to the architecture, which differs fundamentally from Docker.
Each container runs as a child process of Podman.
A user namespace is created on first use when Podman is run with normal user privileges.
Accordingly, the Podman container only has the rights that the executing user has.
Interesting additions to Podman include the mount/unmount command and systemd integration.
In contrast, Docker has to overwrite the firewall rules to enable inter-container communication.
Its better to use Docker as it handles networking much better.
At its simplest, a$ alias docker=podmancommand most of the time works.
Of course, this assumes that the appropriate software is installed on the system.
Windows or macOS are not among the supported operating systems.
The alias approach works because many Docker commands have a Podman equivalent.
But there are also exceptions as some Docker commands have no counterpart in the Podman world.
Similarly, some commands behave differently in Docker than in the Podman universe.
At the moment, this only affects the handling of volumes that have already been set up.
The switch is a bit more difficult when graphical tools such as Docker Desktop are in use.
It should particularly affect those developers who work with Windows or macOS.
However, there is the podman-compose project.
Written in Python, the software serves as a replacement for Docker compose.
Final Words
The replacement of Docker by Podman can be considered almost done.
For users and administrators, most aspects of this change are easy.
Many Docker features have identical equivalents in Podman.
