Why Choose Podman Over Docker? A Complete Guide to Daemon‑less Container Management

What is Podman?

Podman is an open‑source container runtime that works on most Linux platforms. It offers Docker‑compatible functionality but runs without a daemon and can operate without root privileges.

Podman can manage any OCI‑compliant container or image and provides a Docker‑compatible command‑line interface.

Podman website: https://podman.io/

Key Differences Between Podman and Docker

Docker requires a daemon and root privileges, which introduces security risks.

Podman runs without a daemon and does not need root, making its architecture more logical.

Docker uses multiple daemons (dockerd, containerd, containerd‑shim, runc) to implement OCI.

Podman directly calls the OCI runtime (runc) via a common process (conmon), eliminating the need for a root‑owned daemon.

In Podman, the common process is analogous to Docker's containerd‑shim.

The diagram illustrates that Podman does not require a daemon, while Docker’s containerd‑shim and Podman’s common are placed at the same container layer.

Podman vs Docker Usage Differences

Podman aims for Docker compatibility, so most commands are similar. Differences appear in process models and debugging; for example, Podman does not have the multiple daemon processes Docker uses.

From a user perspective, Podman commands cover container runtime (run/start/kill/ps/inspect) and local image management (images/rmi/build, login/pull/push). An alias can map Docker to Podman: alias docker=podman This allows seamless use of Docker commands with Podman.

Common Podman Commands

Containers

podman run           # Create and start a container
podman start         # Start a container
podman ps            # List containers
podman stop          # Stop a container
podman restart       # Restart a container
podman attach        # Attach to a container
podman exec          # Execute a command in a container
podman export        # Export a container
podman import        # Import a container snapshot
podman rm            # Remove a container
podman logs          # View container logs

Images

podman search        # Search images
podman pull          # Pull an image
podman images        # List images
podman rmi           # Remove an image
podman save          # Export an image
podman load          # Import an image
podman build         # Build an image
podman tag           # Tag an image

Deployment

# Install Podman
yum -y install podman

Podman Accelerators

Version 7 accelerator configuration (registries.conf):

# vim /etc/containers/registries.conf
registries = ["docker.io"]
[[docker.io]]
location = "j3m2itm3.mirror.aliyuncs.com"

Version 8 accelerator configuration:

unqualified-search-registries = ["docker.io"]
[[registry]]
prefix = "docker.io"
location = "j3m2itm3.mirror.aliyuncs.com"

Using Podman

Running a container:

# podman run -d --name httpd docker.io/library/httpd
# podman images

Listing running containers:

# podman ps

Note: Adding -a to ps shows all containers.

Inspecting a container:

# podman inspect -l | grep IPAddress

Viewing logs:

# podman logs --latest

Viewing resource usage:

# podman top httpd

Stopping a container:

# podman stop --latest

Removing a container:

# podman rm --latest

Uploading Images

Build and push an image to Docker Hub:

# podman build -t nginx .
# podman tag docker.io/library/nginx:latest docker.io/1314444/test:latest
# podman login docker.io
Username: 1314444
Password: ********
Login Succeeded!
# podman push docker.io/1314444/test:latest

Configuring Aliases

# echo "alias docker=podman" >> ~/.bashrc
source ~/.bashrc

User Operations (Rootless Mode)

Install crun for cgroup V2 support and edit /usr/share/containers/containers.conf to set runtime = "crun". Then run containers as a non‑root user.

Installing slirp4netns and fuse‑overlayfs

# yum -y install slirp4netns
# yum -y install fuse-overlayfs
# vi /etc/containers/storage.conf
mount_program = "/usr/bin/fuse-overlayfs"

/etc/subuid and /etc/subgid Configuration

Rootless users need UID/GID ranges defined in these files. Example:

# useradd zz
# echo "zz:100000:65536" >> /etc/subuid
# echo "zz:100000:65536" >> /etc/subgid

Configuration Files

The three main configuration files are containers.conf, storage.conf, and registries.conf. They can be placed in /etc/containers, /usr/share/containers, or the user’s ~/.config/containers directory, with later locations overriding earlier ones.

Volumes

When a container runs as root, files created inside the container appear as root on the host. Using --userns=keep-id preserves the host user’s UID/GID inside the container.

# podman run -it --name test -v "$(pwd)":/data --userns=keep-id docker.io/library/busybox /bin/sh

Rootless users can map ports >= 1024 by default; to allow lower ports, set net.ipv4.ip_unprivileged_port_start in /etc/sysctl.conf and reload sysctl.

Overall, Podman provides a Docker‑compatible, daemon‑less, rootless container experience with flexible configuration and image management.