🦭 Podman Basics

# Install on RHEL 8/9, Rocky, AlmaLinux
sudo dnf install -y podman

# Install on Ubuntu/Debian
sudo apt install -y podman

# Verify installation
podman --version
podman info | head -20

# Run your first container — hello world
podman run hello-world

# Run an interactive bash session in a container
podman run -it --rm fedora:latest bash

# Run an nginx web server in the background
podman run -d --name webserver -p 8080:80 nginx:latest

# Verify it is running
podman ps
curl http://localhost:8080

# Search for an image
podman search nginx
podman search --filter=is-official nginx

# Pull an image without running it
podman pull nginx:latest
podman pull fedora:39
podman pull quay.io/centos/centos:stream9

# List local images
podman images

# Inspect an image
podman inspect nginx:latest
podman inspect --format '{{.Os}} {{.Architecture}}' nginx:latest

# Show image history (layers)
podman history nginx:latest

# Remove an image
podman rmi nginx:latest

# Remove all unused images
podman image prune

# Remove ALL images
podman rmi -a

# List running containers
podman ps

# List ALL containers including stopped
podman ps -a

# Stop a container gracefully (SIGTERM)
podman stop webserver

# Start a stopped container
podman start webserver

# Restart a container
podman restart webserver

# Kill a container immediately (SIGKILL)
podman kill webserver

# Remove a stopped container
podman rm webserver

# Remove a running container (force)
podman rm -f webserver

# Remove all stopped containers
podman container prune

# Rename a container
podman rename webserver nginx-prod

# Execute a command in a running container
podman exec webserver nginx -t     # test nginx config
podman exec webserver cat /etc/nginx/nginx.conf

# Get an interactive shell in a running container
podman exec -it webserver bash
podman exec -it webserver sh       # if bash not available

# View container logs
podman logs webserver
podman logs -f webserver           # follow (like tail -f)
podman logs --tail 50 webserver    # last 50 lines
podman logs --since 1h webserver   # last hour

# Show container resource usage
podman stats
podman stats webserver

# Show running processes inside container
podman top webserver

# Copy files to/from container
podman cp webserver:/etc/nginx/nginx.conf ./nginx.conf
podman cp ./myconfig.conf webserver:/etc/nginx/conf.d/

# Run container with a named volume (persists across container restarts)
podman run -d \
    --name db \
    -v pgdata:/var/lib/postgresql/data \
    -e POSTGRES_PASSWORD=secret \
    postgres:15

# Run with a bind mount (map a host directory into the container)
podman run -d \
    --name webserver \
    -v /var/www/html:/usr/share/nginx/html:ro \
    -p 8080:80 \
    nginx:latest

# The :ro makes the mount read-only inside the container
# :z or :Z fixes SELinux context on bind mounts (important on RHEL!)
podman run -d \
    -v /mydata:/data:z \
    myapp:latest

# Manage named volumes
podman volume create mydata
podman volume ls
podman volume inspect mydata
podman volume rm mydata
podman volume prune    # remove unused volumes

Podman uses Containerfile (identical format to Dockerfile):

# Example Containerfile for a simple web app
cat > Containerfile << 'EOF'
FROM fedora:39

LABEL maintainer="Craig <craig@binghamton.edu>"
LABEL description="Simple Python web app"

RUN dnf install -y python3 python3-pip && \
    dnf clean all

WORKDIR /app

COPY requirements.txt .
RUN pip3 install -r requirements.txt

COPY . .

EXPOSE 5000

CMD ["python3", "app.py"]
EOF

# Build the image
podman build -t myapp:1.0 .
podman build -t myapp:latest -f Containerfile .

# Build with no cache (force fresh build)
podman build --no-cache -t myapp:latest .

# Tag an image
podman tag myapp:latest myapp:1.0
podman tag myapp:latest quay.io/myuser/myapp:latest

# Push to a registry
podman login quay.io
podman push quay.io/myuser/myapp:latest

Podman's killer feature for sysadmins — generate a systemd unit file from a running container:

# Start the container first
podman run -d \
    --name nginx-prod \
    --restart always \
    -p 80:80 \
    -v /var/www/html:/usr/share/nginx/html:z \
    nginx:latest

# Generate a systemd unit file
podman generate systemd --name nginx-prod --files --new

# This creates: container-nginx-prod.service

# Install as a system service (root)
sudo cp container-nginx-prod.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now container-nginx-prod

# Install as a user service (rootless)
mkdir -p ~/.config/systemd/user/
cp container-nginx-prod.service ~/.config/systemd/user/
systemctl --user daemon-reload
systemctl --user enable --now container-nginx-prod

# Enable lingering so user services survive logout
loginctl enable-linger $USER

# Manage like any systemd service
sudo systemctl status container-nginx-prod
sudo systemctl restart container-nginx-prod
sudo journalctl -u container-nginx-prod -f

Podman is designed as a drop-in Docker replacement. Most commands are identical:

# If you have muscle memory for docker commands:
alias docker=podman

# Or install the docker-compatibility package
sudo dnf install -y podman-docker