Luet – Resources

Docs: ARM images

Mon, 01 Jan 0001 00:00:00 +0000

Warning

This article is outdated. Please refer to the “Hello World” tutorial instead.

Here we show an example on how to build “burnable” SD images for Raspberry Pi with Luet. This approach lets you describe and version OTA upgrades for your embedded devices, delivering upgrades as layer upgrades on the Pi.

The other good side of the medal is that you can build a Luet package repository with multiple distributions (e.g. Raspbian, OpenSUSE, Gentoo, … ) and switch among them in runtime. In the above example Raspbian and Funtoo (at the time of writing) are available.

Prerequisites

You have to run the following steps inside an ARM board to produce arm-compatible binaries. Any distribution with Docker will work. Note that the same steps could be done in a cross-compilation approach, or with qemu-binfmt in a amd64 host.

You will also need in your host:

Docker
Luet installed (+container-diff) in /usr/bin/luet (arm build)
make

Build the packages

Clone the repository https://github.com/Luet-lab/luet-embedded

$> git clone https://github.com/Luet-lab/luet-embedded
$> cd luet-embedded
$> sudo make build-all
...

If a rebuild is needed, just do sudo make rebuild-all after applying the changes.

Create the repository

$> sudo make create-repo
...

Serve the repo locally

$> make serve-repo
...

Create the flashable image

Funtoo based system

$> sudo LUET_PACKAGES='distro/funtoo-1.4 distro/raspbian-boot-0.20191208 system/luet-develop-0.5' make image
...

Raspbian based system

$> sudo LUET_PACKAGES='distro/raspbian-0.20191208 distro/raspbian-boot-0.20191208 system/luet-develop-0.5' make image
...

At the end of the process, a file luet_os.img, ready to be flashed to an SD card, should be present in the current directory.

Add packages

In order to build and add packages to the exiting repository, simply add or edit the specfiles under the distro folder. When doing make rebuild-all the packages will be automatically compiled and made available to the local repository.

Docs: Building

Mon, 01 Jan 0001 00:00:00 +0000

Simple package build

Creating and building a simple package:

$> mkdir package

$> cat <<EOF > package/build.yaml
image: busybox
steps:
- echo "foo" > /foo
EOF

$> cat <<EOF > package/definition.yaml
name: "foo"
version: "0.1"
EOF

$> luet build --all

📦  Selecting  foo 0.1
📦  Compiling foo version 0.1 .... ☕
🐋  Downloading image luet/cache-foo-bar-0.1-builder
🐋  Downloading image luet/cache-foo-bar-0.1
📦   foo Generating 🐋  definition for builder image from busybox
🐋  Building image luet/cache-foo-bar-0.1-builder
🐋  Building image luet/cache-foo-bar-0.1-builder done
 Sending build context to Docker daemon  4.096kB
 ...

Build packages

In order to build a specific version, a full package definition (triple of category, name and version) has to be specified. In this example we will also enable package compression (gzip).

$> mkdir package

$> cat <<EOF > package/build.yaml
image: busybox
steps:
- echo "foo" > /foo
EOF

$> cat <<EOF > package/definition.yaml
name: "foo"
version: "0.1"
category: "bar"
EOF

$> luet build bar/foo-0.1 --compression gzip

📦  Selecting  foo 0.1
📦  Compiling foo version 0.1 .... ☕
🐋  Downloading image luet/cache-foo-bar-0.1-builder
🐋  Downloading image luet/cache-foo-bar-0.1
📦   foo Generating 🐋  definition for builder image from busybox
🐋  Building image luet/cache-foo-bar-0.1-builder
🐋  Building image luet/cache-foo-bar-0.1-builder done
 Sending build context to Docker daemon  4.096kB
 ...

Docs: Frequently Asked Questions

Mon, 01 Jan 0001 00:00:00 +0000

Can’t build packages

There might be several reasons why packages fails to build, for example, if your build fails like this:

$ luet build ...

 INFO   Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
  ERROR    Error: Failed compiling development/toolchain-go-0.6: failed building package image: Could not push image: quay.io/mocaccino/micro-toolchain:latest toolchain-go-development-0.6-builder.dockerfile: Could not build image: quay.io/mocaccino/micro-toolchain:latest toolchain-go-development-0.6-builder.dockerfile: Failed running command: : exit status 1
  ERROR    Bailing out

means the user you are running the build command can’t either connect to docker or docker is not started.

Check if the user you are running the build is in the docker group, or if the docker daemon is started.

Luet by default if run with multiple packages summarize errors and can be difficult to navigate to logs, but if you think you might have found a bug, run the build with --debug before opening an issue.

Why the name `luet`?

Well, I have the idea that programs should be small, so they are not difficult to type and easy to remember, and easy to stick in. luet is really a combination of the first letters of my fiancee name (Lucia) and my name (Ettore) lu+et = luet! and besides, happen to be also a small bridge in Italy ;)

Docs: Images from scratch

Mon, 01 Jan 0001 00:00:00 +0000

The Docker image quay.io/luet/base is a scratch Docker image always kept up-to-date with the latest luet version. That image can be used to bootstrap new images with Luet repositories with the packages you want, from the repositories you prefer.

For example we can mount a config file, and later on install a package:

cat <<EOF > $PWD/luet.yaml  
repositories: 
  - name: "micro-stable"
    enable: true
    cached: true
    priority: 1
    type: "http"
    urls: 
    - "https://get.mocaccino.org/mocaccino-micro-stable"
EOF

docker rm luet-runtime-test || true
docker run --name luet-runtime-test \
       -ti -v /tmp:/tmp \
       -v $PWD/luet.yaml:/etc/luet/luet.yaml:ro \
       quay.io/luet/base install shells/bash
 
docker commit luet-runtime-test luet-runtime-test-image

# Try your new image!

docker run -ti --entrypoint /bin/bash --rm luet-runtime-test-image

In this way we will create a new image, with only luet and bash, and nothing else from a scratch image.

Docs: References

Mon, 01 Jan 0001 00:00:00 +0000

References

Here is a list of references to projects that are related to Luet (open up a PR to add yours to the list!):

Description	URL
Official Luet repository	https://github.com/Luet-lab/luet-repo
Example repository to host package browser websites on gh-pages. It uses the package-browser extension to generate HTML pages from a list of luet repositories	https://github.com/Luet-lab/package-browser-sample
LineageOS builds with luet	https://github.com/mudler/android-builds
Example repository template to build packages on github actions and push packages on a container registry	https://github.com/Luet-lab/github-repository
Immutable container OS toolkit	https://github.com/rancher-sandbox/cOS-toolkit
mocaccinoOS desktop	https://github.com/mocaccinoOS/desktop
mocaccinoOS extra	https://github.com/mocaccinoOS/mocaccino-extra
agregOS built with luet/mocaccino	https://interne.agreg.org/agregOS/

Luet – Resources

Docs: ARM images

Warning

Prerequisites

Build the packages

Create the repository

Serve the repo locally

Create the flashable image

Funtoo based system

Raspbian based system

Add packages

Docs: Building

Simple package build

Build packages

Docs: Frequently Asked Questions

Can’t build packages

Why the name luet?

Docs: Images from scratch

Docs: References

References

Why the name `luet`?