SkiffOS is a lightweight operating system for any Linux-compatible computer, ranging from RPi, Odroid, NVIDIA Jetson, to Desktop PCs, Laptops (i.e. Apple MacBook), Phones (PinePhone), Containers, or Cloud VMs. It is:
- Adoptable: any userspace can be imported/exported to/from container images.
- Familiar: uses simple Makefile and KConfig language for configuration.
- Flexible: supports all major OS distributions inside containers.
- Portable: containers can be moved between machines of similar CPU type.
- Reliable: changes inside user environments cannot break the host boot-up.
- Reproducible: a given Skiff Git tree will always produce identical output.
Uses Buildroot to produce a minimal "single-file" host OS as a standardized base cross-platform operating system "shim" for hosting containers. Most Linux platforms have widely varying requirements for kernel, firmware, and additional hardware support packages. The immutable SkiffOS host system contains everything needed to support the hardware, cleanly separated from the applications.
The SKIFF_CONFIG comma-separated environment variable selects which
configuration layers should be merged together to configure the build.
$ make # lists all available layers
$ export SKIFF_CONFIG=pi/4,skiff/core
$ make configure # configure the system
$ make compile # build the systemAfter you run make configure Skiff will remember what you selected in
SKIFF_CONFIG. The compile command instructs Skiff to build the system.
Adjustments can be made to configuration layers, and make compile can be
called again to re-pack the system image without re-building everything.
You can add your SSH public key to the target image by adding it to
overrides/root_overlay/etc/skiff/authorized_keys/my-key.pub, or by adding it
to your own custom configuration package.
The example above uses pi/4, which can be replaced with any of the hardware
support packages listed in the Supported Systems table.
Once the build is complete, it's time to flash the system to a SD card. You will
need to switch to sudo bash for this on most systems.
$ sudo bash # switch to root
$ blkid # look for your SD card's device file
$ export PI_SD=/dev/sdz # make sure this is right!
$ make cmd/pi/common/format # tell skiff to format the device
$ make cmd/pi/common/install # tell skiff to install the osThe device needs to be formatted only one time, after which, the install command can be used to update the SkiffOS images without clearing the persistent state. The persist partition is not touched in this step, so anything you save there, including Docker state and system configuration, will not be modified.
There are many other utility commands made available by Buildroot, which can be
listed using make br/help, some examples:
$ make br/menuconfig # optionally explore Buildroot config
$ make br/sdk # build relocatable SDK for target
$ make br/graph-size # graph the target packages sizesConnect using SSH to root@my-ip-address to access the SkiffOS system, and
connect to core@my-ip-address to access the "Core" system container. The
mapping between users and containers can be edited in the
/mnt/persist/skiff/core/config.yaml file.
The system can then be upgraded over-the-air (OTA) using the rsync script:
$ ./scripts/push_image.bash root@my-ip-addressThe SkiffOS upgrade (or downgrade) will take effect on next reboot.
SkiffOS is based on Buildroot, which can compile operating systems for any Linux-compatible machine.
Here are the boards/systems currently supported:
| Board | Config Package | Bootloader | Kernel | Notes |
|---|---|---|---|---|
| Docker Img | virt/docker | N/A | N/A | Run in Docker |
| Qemu | virt/qemu | N/A | ✔ 5.14.15 | Run in QEmu |
| WSL on Windows | virt/wsl | N/A | ✔ msft-5.4.72 | Run in WSL2 |
| Apple Macbook | apple/macbook | ✔ rEFInd | ✔ 5.14.15 | ✔ Tested |
| BananaPi M1 | bananapi/m1 | ✔ U-Boot 2020.10 | ✔ 5.14.15 | ⚠ Obsolete |
| BananaPi M1+/Pro | bananapi/m1plus | ✔ U-Boot 2020.10 | ✔ 5.14.15 | ⚠ Obsolete |
| BananaPi M2+ | bananapi/m2plus | ✔ U-Boot 2020.10 | ✔ 5.14.15 | |
| BananaPi M3 | bananapi/m3 | ✔ U-Boot 2020.10 | ✔ 5.14.15 | ✔ Tested |
| Intel x86/64 | intel/x64 | ✔ Grub | ✔ 5.14.15 | ✔ Tested |
| NVIDIA Jetson Nano | jetson/nano | ✔ U-Boot | ✔ 4.9.140 | ✔ Tested |
| NVIDIA Jetson TX2 | jetson/tx2 | ✔ U-Boot | ✔ 4.9.140 | ✔ Tested |
| Odroid C2 | odroid/c2 | ✔ U-Boot 2020.10 | ✔ tb-5.13.15 | ⚠ Obsolete |
| Odroid C4 | odroid/c4 | ✔ U-Boot 2021.01 | ✔ tb-5.13.15 | ✔ Tested |
| Odroid U | odroid/u | ✔ U-Boot 2016.03 | ✔ tb-5.13.15 | ⚠ Obsolete |
| Odroid HC1 | odroid/xu | ✔ U-Boot 2019.04 | ✔ tb-5.13.15 | ✔ Tested |
| Odroid HC2 | odroid/xu | ✔ U-Boot 2019.04 | ✔ tb-5.13.15 | ✔ Tested |
| Odroid XU3 | odroid/xu | ✔ U-Boot 2019.04 | ✔ tb-5.13.15 | ⚠ Obsolete |
| Odroid XU4 | odroid/xu | ✔ U-Boot 2019.04 | ✔ tb-5.13.15 | ✔ Tested |
| OrangePi Lite | orangepi/lite | ✔ U-Boot 2018.05 | ✔ 5.14.15 | |
| OrangePi Zero | orangepi/zero | ✔ U-Boot 2018.07 | ✔ 5.14.15 | |
| PcDuino 3 | pcduino/3 | ✔ U-Boot 2019.07 | ✔ 5.14.15 | |
| PcEngines APU2 | pcengines/apu2 | ✔ CoreBoot | ✔ 5.14.15 | |
| Pi 0 | pi/0 | N/A | ✔ rpi-5.10.73 | ✔ Tested |
| Pi 1 | pi/1 | N/A | ✔ rpi-5.10.73 | |
| Pi 3 + 1, 2 | pi/3 | N/A | ✔ rpi-5.10.73 | ✔ Tested |
| Pi 4 | pi/4 | N/A | ✔ rpi-5.10.73 | ✔ Tested |
| Pi 4 (32bit mode) | pi/4x32 | N/A | ✔ rpi-5.10.73 | ✔ Tested |
| Pine64 H64 | pine64/h64 | ✔ U-Boot | ✔ pine64-5.8.0 | ✔ Tested |
| PineBook Pro | pine64/book | ✔ U-Boot (bin) | ✔ ayufan-5.13.0 | ✔ Tested |
| PinePhone | pine64/phone | ✔ U-Boot (bin) | ✔ megi-5.14.10 | ✔ Tested |
| RockPro64 | pine64/rockpro64 | ✔ U-Boot (bin) | ✔ ayufan-5.13.0 | ✔ Tested |
| USBArmory Mk2 | usbarmory/mk2 | ✔ U-Boot 2020.10 | ✔ 5.14.15 | ✔ Tested |
All targets marked "tested" use automated end-to-end testing on real hardware. Targets marked "Obsolete" are discontinued by their manufacturer but still have a corresponding SkiffOS configuration and should still work.
Adding support for a board involves creating a Skiff configuration package for the board, as described above. If you have a device that is not yet supported by SkiffOS, please open an issue.
The Skiff Core subsystem, enabled with the skiff/core layer or by selecting
any of the core environment packages, automatically configures mappings between
users and containerized environments. It maps incoming SSH sessions accordingly:
- Configured using a YAML configuration file
skiff-core.yaml. - The container image is either pulled or built from scratch.
- systemd and/or other init systems operate as PID 1 inside the container.
This allows virtually any workflow to be migrated to Skiff. The config file structure is flexible, and allows for any number of containers, users, and images to be defined and built.
Any existing GNU/Linux system with compatibility with the running kernel version
can be loaded as a Docker image with the docker import command.
All core configurations work with all target platforms:
| Distribution | Config Package | Notes |
|---|---|---|
| Alpine Linux | core/alpine | OpenRC |
| Debian Bullseye | core/debian | |
| DietPi | core/dietpi | DietPi applications tool |
| Gentoo | core/gentoo | Based on latest stage3 |
| NASA cFS Framework | core/nasa_cfs | Flight software framework |
| NASA Fprime Framework | core/nasa_fprime | Flight software framework |
| NixOS | core/nixos | |
| NixOS for PinePhone | core/pinephone_nixos | |
| NixOS with XFCE | core/nixos_xfce | |
| Ubuntu | skiff/core | With minimal desktop GUI |
| PineBook Manjaro KDE | core/pinebook_manjaro_kde | KDE Variant |
| PinePhone KDE Neon | core/pinephone_neon | Ubuntu-based KDE Neon |
| PinePhone Manjaro KDE | core/pinephone_manjaro_kde | KDE Variant |
| PinePhone Manjaro Lomiri | core/pinephone_manjaro_lomiri | Lomiri variant |
| PinePhone Manjaro Phosh | core/pinephone_manjaro_phosh | Phosh variant |
| PinePhone UBTouch | core/pinephone_ubtouch | Ubuntu touch |
The default configuration creates a user named "core" mapped into a container,
but this can be easily configured in the skiff-core.yaml configuration file:
containers:
core:
image: skiffos/skiff-core-gentoo:latest
[...]
users:
core:
container: core
containerUser: core
[...]To customize the core configuration after booting into SkiffOS, edit the file at
/mnt/persist/skiff/core/config.yaml and run systemctl restart skiff-core to
apply.
There are three release channels: next, master, and stable.
Skiff can be upgraded or downgraded (rolled back) independently from the persistent storage partition. This allows for easy OTA, and significant improvements in confidence when upgrading system components.
Skiff supports modular configuration packages. A configuration directory contains kernel configs, buildroot configs, system overlays, etc.
These packages are denoted as namespace/name. For example, an ODROID XU4
configuration would be odroid/xu.
Configuration package directories should have a depth of 2, where the first directory is the category name and the second is the package name.
A configuration package is laid out into the following directories:
├── cflags: compiler flags in files
├── buildroot: buildroot configuration fragments
├── buildroot_ext: buildroot extensions (extra packages)
├── buildroot_patches: extra Buildroot global patches
│ ├── <packagename>: patch files for Buildroot <packagename>
│ └── <packagename>/<version>: patches for package version
├── extensions: extra commands to add to the build system
│ └── Makefile
├── hooks: scripts hooking pre/post build steps
│ ├── post.sh
│ └── pre.sh
├── kernel: kernel configuration fragments
├── kernel_patches: kernel .patch files
├── root_overlay: root overlay files
├── metadata: metadata files
│ ├── commands
│ ├── dependencies
│ ├── description
│ └── unlisted
├── resources: files used by the configuration package
├── scripts: any scripts used by the extensions
├── uboot: u-boot configuration fragments
└── uboot_patches: u-boot .patch files
All files are optional.
You can set the following env variables to control this process:
SKIFF_CONFIG_PATH_ODROID_XU: Set the path for the ODROID_XU config package. You can set this to add new packages or override old ones.SKIFF_EXTRA_CONFIGS_PATH: Colon separated list of paths to look for config packages.SKIFF_CONFIG: Name of skiff config to use, or comma separated list to overlay, with the later options taking precedence
These packages will be available in the Skiff system.
It's often useful to be able to adjust the buildroot, kernel, or other configurations locally during development without actually creating a new configuration layer. This can be easily done with the overrides system.
The overrides directory, as well as the
overrides/workspaces/$SKIFF_WORKSPACE directory, are automatically used as
additional Skiff configuration packages. You can follow the Skiff configuration
package format as defined below to override any of the settings in Buildroot or
the Linux kernel, add extra Buildroot packages, add build hooks, etc.
Workspaces allow you to configure and compile multiple systems at a time.
Set SKIFF_WORKSPACE to the name of the workspace you want to use. The
Buildroot setup will be constructed in workspaces/$SKIFF_WORKSPACE. You can
also place configuration files in overrides/workspaces/$SKIFF_WORKSPACE/ to
override settings for that particular workspace locally.
The virt/ packages are designed for running Skiff in various virtualized environments.
Here is a minimal working example of running Skiff in Qemu:
$ SKIFF_CONFIG=virt/qemu make configure compile
$ make cmd/virt/qemu/runHere is a minimal working example of running Skiff in Docker:
$ SKIFF_CONFIG=virt/docker,skiff/core make configure compile
$ make cmd/virt/docker/buildimage
$ make cmd/virt/docker/run
# inside container
$ su - coreThe build command compiles the image, and run executes it.
You can execute a shell inside the container with:
$ make cmd/virt/docker/exec
# alternatively
$ docker exec -it skiff shAlternatively, run the latest demo release on Docker Hub:
docker run -t -d --name=skiff \
--privileged \
--cap-add=NET_ADMIN \
--security-opt seccomp=unconfined \
--stop-signal=SIGRTMIN+3 \
-v /sys/fs/cgroup:/sys/fs/cgroup:ro \
-v $(pwd)/skiff-persist:/mnt/persist \
skiffos/skiffos:latest
SkiffOS includes a systemd-based configuration and a standard partition layout, with boot files separated from the persistent data, on default. This can be disabled, overridden, and/or customized by other configuration packages.
Skiff uses NetworkManager to manage network connections.
Network configurations are loaded from /etc/NetworkManager/system-connections
and from skiff/connections on the persist partition.
The configuration file format for these connections is documented here with examples.
You can use nmcli on the device to manage NetworkManager, and any connection
definitions written by nmcli device wifi connect or similar will automatically
be written to the persist partition and persisted to future boots.
You can set the hostname by placing the desired hostname in the skiff/hostname
file on the persist partition. You could also set this in one of your config
packages by writing the desired hostname to /etc/hostname.
The system on boot will generate the authorized_keys file for root.
It takes SSH public key files (*.pub) from these locations:
/etc/skiff/authorized_keysfrom inside the imageskiff/keysfrom inside the persist partition
To mount a Linux disk, for example an ext4 partition, to a path inside a
Docker container, you can use the Docker Volumes feature:
# Determine the UUID of your volume
# Look for your disk & get the UUID
blkid
# Create "my-volume" with the UUID.
# Replace with your UUID from the previous command.
docker volume create --driver=local --opt type=ext4 --opt device=/dev/disk/by-uuid/d21c6d3a-461e-4d7d-8732-40e56e8f184a my-volume
# Run a container with the drive mounted to a path.
docker run -v my-volume:/my-volume --rm -it alpine shThe volumes and containers state is stored in the "persist" partition and will remain between reboots, while the SkiffOS host system is ephemeral.
You can build Skiff inside Docker if you encounter any incompatibility with your build host operating system.
If you encounter issues or questions at any point when using Skiff, please file a GitHub issue and/or Join Discord.