Talos Linux Overlays

This repo servers a central place for the list of all official Talos Linux overlays. Overlays are a way to extend the installation procedure of Talos to support SBC's.

Using Overlays

Overlays referenced in this repo are published as container images. These images can be added to the the Talos Linux boot asset to produce a final boot asset containing that supports the specific overlay implementation.

The overlays image is composed of a overlays.yaml file that provides the list of published overlays and the corresponding container image.

In order to find a container reference for an overlay you can use the following commands:

crane export ghcr.io/siderolabs/extensions:v<talos-version> | tar x -O overlays.yaml | yq '.overlays[] | select(.name == "<overlay-name>") | .image + "@" + .digest'

Please always use the pinned digest when referencing an overlay image.

All overlays and the overlay catalogue image are signed with Google Accounts OIDC issuer matching @siderolabs.com domain, so the image signatures can be verified, for example:

cosign verify --certificate-identity-regexp '@siderolabs\.com$' --certificate-oidc-issuer https://accounts.google.com ghcr.io/siderolabs/overlays:v1.7.0
cosign verify --certificate-identity-regexp '@siderolabs\.com$' --certificate-oidc-issuer https://accounts.google.com ghcr.io/siderolabs/sbc-raspberry-pi:v0.1.0

The list of available overlays can be found in the Overlays Catalog section below.

Overlays Catalog

Overlay Name	Board	Repository
rpi_generic	Raspberry Pi 4/Compute Module 4	sbc-raspberrypi
nanopi-r4s	NanoPi R4S	sbc-rockchip
nanopi-r5s	NanoPi R5S	sbc-rockchip
rock64	Pine64 Rock64	sbc-rockchip
rockpi4	Rock Pi 4A,Rock Pi 4B	sbc-rockchip
rockpi4c	Rock Pi 4C	sbc-rockchip
rock4cplus	Radxa ROCK 4C+	sbc-rockchip
rock4se	Radxa ROCK 4SE	sbc-rockchip
helios64	Kobol Helios64	sbc-rockchip
jetson_nano	Jetson Nano	sbc-jetson
bananapi_m64	BananaPi M64	sbc-allwinner
libretech_all_h3_cc_h5	LibreTech H3 CC H5	sbc-allwinner
pine64	Pine64 A64	sbc-allwinner

Building Overlays

A new overlay can be created using the SBC Template repository as a starting point and replacing all references of board with your SBC name.

Then followed by running make rekres to automatically generate/update all the required files. Then the user can run make help on instructions on how to setting up docker buildx.

Note: Run make rekres after any changes to the .kres.yaml file or before committing any changes.

It is highly recommended to take a look at an existing overlays from the catalog as a template for building your own.

Folder Structure

An overlay container image should have the following folder structure:

.
├── artifacts
│   └── arm64
│       ├── dtb
│       │   └── rpi_4
│       ├── firmware
│       │   └── rpi4
│       │       └── firmware_20240302.bin
│       └── u-boot
│           └── rpi4.uboot.img
├── installers
│   └── rpi_generic
└── profiles
    ├── rpi_4.yaml
    └── rpi_5.yaml

12 directories, 3 files

An overlay can provide multiple installers and profiles for a group of SBC's.

The artifacts folder contains the files that will be copied to the Talos boot and installer assets. This is an optional folder, if the overlay does not require any artifacts to be copied to the boot asset, it can be omitted.

The installers folder contains statically linked binaries named after the profile names. If an overlay provides only a single profile it can be named default.

The profiles folder contains the list of profiles that the overlay supports. Talos Imager will register profiles based on the file names in this folder.

Installer implementation

The installer is a statically linked binary that is responsible for providing the logic Talos Imager will consume to generate a boot asset.

Installer can be any statically linked binary and has to be provided for both amd64 and arm64 architectures.

Sidero Labs will provide an official Go wrapper to handle the communication between the installer and Talos Imager.

Sidero Labs provides an adapter package than can used as the entrypoint of the Go program.

The Go code should implement the overlay.Installer interface.

An example of a simple installer can be found in the sbc-template.

Refer to using Custom installers for more information on how to use custom installers.

Custom Installers

Custom Installers can be written in any language as long as they follow the conditions below:

• The binary has to accept stdin as yaml input and output yaml to stdout.
• The binary should exit with a non-zero status code if an error occurs.
• The binary should implement install and get-options as argv[1].

get-options accepts a yaml input of arbitrary extraOptions passed from the imager and should output a yaml to stdout conforming to the overlay.Options.

install accepts a yaml input conforming to overlay.InstallOptions and outputs an empty yaml to stdout.

The installer get-options and install commands can use the provided inputs to perform any necessary operations to install the overlay on the target device.

Profiles

Profiles define the output image format and base metal image size for an overlay. This would rarely change and the default profile generated from sbc-template should be sufficient for most cases.