Kas (yocto helper tool)

Kas is a python-based tool for automating yocto-based builds.

It relies on a YAML configuration file that describes what meta-layers need to be downloaded (the repos section), what’s the default image for the build and what should be included in the conf/local.conf file (the local_conf_header section). The conf/bblayers.conf file is automatically populated, based on the repos section.

Installing kas.
⚠️Note: If you already have kas installed, this command will do nothing (even if the upstream version is newer than the local version).
```
pip3 install kas
```
Upgrading kas.
```
pip3 install --upgrade kas
```
Clone (if needed), set up (if needed) and start a build, using parameters from a file named description.yml.
⚠️Note: If the configuration file specifies a branch that has been updated upstream, and the locally-cloned repository is stale, the local clone will not be updated.
```
kas build description.yml
```
Clone (if needed), set up (if needed) and start a build, but update the local clones of the repositories.
```
kas build --update description.yml
```
Start a build, while overriding the default target package.
```
kas build description.yml --target virtual/kernel
```
Start a build, while overriding the default task.
The default task is do_build, as defined by BB_DEFAULT_TASK.
```
kas build description.yml --task do_clean
```
Start a build, and pass an argument (e.g. --continue, to continue building even after encountering errors) directly to bitbake. This kind of arguments must be at the end of the command, end prefixed by a double dash. The official documentation names them extra_bitbake_args.
```
kas build description.yml -- --continue
```
Clone the repositories.
```
kas checkout description.yml
```
Set everything up and start a shell for yocto-based commands.
The shell will be started with source ./poky/oe-init-build-env ./build.
```
kas shell description.yml
```

Making a YAML file

Sample description.yml file.

header:
  version: 11

machine: raspberrypi4-64
distro: poky
target: core-image-minimal

repos:
  poky:
    url: https://git.yoctoproject.org/git/poky
    refspec: dunfell
    layers:
      meta:
      meta-poky:

  meta-openembedded:
    url: http://git.openembedded.org/meta-openembedded
    refspec: dunfell
    path: poky/meta-openembedded
    layers:
      meta-oe:
      meta-python:

  meta-raspberrypi:
    url: https://github.com/agherzan/meta-raspberrypi/
    path: poky/meta-raspberrypi
    refspec: dunfell

local_conf_header:
  standard: |
    CONF_VERSION = "1"
    PACKAGE_CLASSES = "package_rpm"
    SDKMACHINE = "x86_64"
    USER_CLASSES = "buildstats image-mklibs image-prelink"
    PATCHRESOLVE = "noop"

  debug-tweaks: |
    EXTRA_IMAGE_FEATURES = "debug-tweaks ssh-server-dropbear package-management"

  diskmon: |
    BB_DISKMON_DIRS = "\
        STOPTASKS,${TMPDIR},1G,100K \
        STOPTASKS,${DL_DIR},1G,100K \
        STOPTASKS,${SSTATE_DIR},1G,100K \
        STOPTASKS,/tmp,100M,100K \
        ABORT,${TMPDIR},100M,1K \
        ABORT,${DL_DIR},100M,1K \
        ABORT,${SSTATE_DIR},100M,1K \
        ABORT,/tmp,10M,1K"

The refspec parameter can point to either a git branch, tag or commit hash.
The layers parameter is optional, and is used only if the repository contains multiple meta-layers.
The path parameter is optional, and is used to specify where (relative to the current directory) the repository will be cloned.
The fragments under the local_conf_header section can have any name. All these fragments will be concatenated and placed in the configuration file.