engine

rfswift –engine

Select the container engine used by RF Swift.

Synopsis

rfswift --engine ENGINE [command] [options]

The --engine flag is a global flag that overrides RF Swift’s auto-detection and forces a specific container engine for the current command. It must be placed before any subcommand.

Options

Auto-Detection Behavior

When --engine is not specified, RF Swift automatically detects the available container engine at startup using the following priority:

1. Is Podman installed?        → check podman binary + fallback paths
2. Is Docker installed?        → check docker binary
3. Is podman-docker shim active? → detect via `docker --version` containing "podman"
4. Is Docker daemon running?   → verify daemon connectivity

# Force Docker
rfswift --engine docker run -i sdr_full -n my_container

# Force Podman
rfswift --engine podman run -i sdr_full -n my_container

rfswift run -i sdr_full -n my_container
# → uses Docker

rfswift run -i sdr_full -n my_container
# → uses Podman

❌ No container engine found. Please install Docker or Podman.
 Run ./install.sh or visit https://rfswift.io/docs/getting-started/

Examples

Force Docker

# Pull image with Docker
rfswift --engine docker images pull -i sdr_full

# Run container with Docker
rfswift --engine docker run -i sdr_full -n my_sdr

# List containers managed by Docker
rfswift --engine docker last

Force Podman

# Pull image with Podman
rfswift --engine podman images pull -i sdr_full

# Run rootless container with Podman
rfswift --engine podman run -i sdr_full -n rootless_sdr

# List containers managed by Podman
rfswift --engine podman last

Mixed Workflows

If both engines are installed, you can maintain separate environments:

# Docker for privileged hardware work
rfswift --engine docker run -i sdr_full -n docker_sdr \
  -u 1 \
  -s /dev/bus/usb:/dev/bus/usb

# Podman for rootless analysis
rfswift --engine podman run -i reversing -n podman_analysis \
  -u 0 \
  -t none \
  -b ~/samples:/root/samples:ro

Engine Comparison

Podman-Specific Notes

Rootless Configuration

Podman runs rootless by default. Ensure your system is configured:

# Check subordinate UID/GID ranges
grep $USER /etc/subuid /etc/subgid

# If empty, configure them
sudo usermod --add-subuids 100000-165535 $USER
sudo usermod --add-subgids 100000-165535 $USER

# Enable lingering (containers survive logout)
sudo loginctl enable-linger $USER

# Enable Podman socket (Docker API compatibility)
systemctl --user enable --now podman.socket

Image Registry

Podman may prompt for a registry when using short image names:

# Full name (no prompt)
rfswift --engine podman images pull -i docker.io/penthertz/rfswift:sdr_full

# Short name (may prompt for registry selection)
rfswift --engine podman images pull -i sdr_full

To avoid prompts, configure default registries in /etc/containers/registries.conf:

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

Privileged Mode Differences

In rootless Podman, -u 1 (privileged) grants privileges within the user namespace, which is still more restricted than Docker’s privileged mode:

# Docker privileged = full host root access
rfswift --engine docker run -i sdr_full -n docker_priv -u 1

# Podman privileged = root within user namespace (safer)
rfswift --engine podman run -i sdr_full -n podman_priv -u 1

Cgroup Compatibility

RF Swift auto-detects cgroup v1 and v2 and configures device access rules accordingly. No manual configuration is needed.

Docker-Specific Notes

Daemon Requirement

Docker requires its daemon to be running:

# Check daemon status
sudo systemctl status docker

# Start if stopped
sudo systemctl start docker

# Enable at boot
sudo systemctl enable docker

Group Membership

To run Docker without sudo:

sudo usermod -aG docker $USER
newgrp docker

Troubleshooting

Engine Not Found

Error: No container engine found

Solution:

# Install via RF Swift installer
curl -fsSL "https://get.rfswift.io/" | sh

# Or install manually
sudo apt install podman     # Debian/Ubuntu
sudo dnf install podman     # Fedora
curl -fsSL https://get.docker.com | sudo sh  # Docker

Wrong Engine Detected

Problem: RF Swift picks Docker when you want Podman (or vice versa)

Solution:

# Explicit override
rfswift --engine podman run -i sdr_full -n my_container

podman-docker Shim Detected as Docker

Problem: podman-docker package makes docker command available but it’s actually Podman

Solution: RF Swift handles this automatically. It checks docker --version output for the word “podman” and correctly identifies the engine. No action needed.

Containers Not Visible Across Engines

Problem: Created a container with Docker but can’t see it with Podman

Solution: This is expected behavior. Each engine manages its own containers and images independently. Use the same --engine flag you used to create the container:

# If created with Docker
rfswift --engine docker exec -c my_container

# If created with Podman
rfswift --engine podman exec -c my_container

Related

• run - Create and run containers
• exec - Enter existing containers
• images - Manage container images
• Getting Started - Installation and engine setup
• Container Engine Support - Requirements and platform support