Project Configuration

Currently, JSON and YAML are supported as the base file formats. Since YAML is arguably easier to read, this documentation focuses on the YAML format.

# Every file needs to contain a header, that provides kas with information
# about the context of this file.
header:
  # The `version` entry in the header describes for which configuration
  # format version this file was created for. It is used by kas to figure
  # out if it is compatible with this file. The version is an integer that
  # is increased on every format change.
  version: x
# The machine as it is written into the `local.conf` of bitbake.
machine: qemux86-64
# The distro name as it is written into the `local.conf` of bitbake.
distro: poky
repos:
  # This entry includes the repository where the config file is located
  # to the bblayers.conf:
  meta-custom:
  # Here we include a list of layers from the poky repository to the
  # bblayers.conf:
  poky:
    url: "https://git.yoctoproject.org/git/poky"
    commit: 89e6c98d92887913cadf06b2adb97f26cde4849b
    layers:
      meta:
      meta-poky:
      meta-yocto-bsp:

A minimal input file consists out of the header, machine, distro, and repos.

Additionally, you can add bblayers_conf_header and local_conf_header which are strings that are added to the head of the respective files (bblayers.conf or local.conf):

bblayers_conf_header:
  meta-custom: |
    POKY_BBLAYERS_CONF_VERSION = "2"
    BBPATH = "${TOPDIR}"
    BBFILES ?= ""
local_conf_header:
  meta-custom: |
    PATCHRESOLVE = "noop"
    CONF_VERSION = "1"
    IMAGE_FSTYPES = "tar"

meta-custom in these examples should be a unique name for this configuration entries.

We recommend that this unique name is the same as the name of the containing repository/layer to ease cross-project referencing.

In given examples we assume that your configuration file is part of a meta-custom repository/layer. This way it is possible to overwrite or append entries in files that include this configuration by naming an entry the same (overwriting) or using an unused name (appending).

Including in-tree configuration files

It’s currently possible to include kas configuration files from the same repository/layer like this:

header:
  version: x
  includes:
    - base.yml
    - bsp.yml
    - product.yml

The paths to the files in the include list are either absolute, if they start with a /, or relative.

If the path is relative and the configuration file is inside a repository, then path is relative to the repositories base directory. If the configuration file is not in a repository, then the path is relative to the parent directory of the file.

Including configuration files from other repos

It’s also possible to include configuration files from other repos like this:

header:
  version: x
  includes:
    - repo: poky
      file: kas-poky.yml
    - repo: meta-bsp-collection
      file: hw1/kas-hw-bsp1.yml
    - repo: meta-custom
      file: products/product.yml
repos:
  meta-custom:
  meta-bsp-collection:
    url: "https://www.example.com/git/meta-bsp-collection"
    commit: 3f786850e387550fdab836ed7e6dc881de23001b
    layers:
      # Additional to the layers that are added from this repository
      # in the hw1/kas-hw-bsp1.yml, we add here an additional bsp
      # meta layer:
      meta-custom-bsp:
  poky:
    url: "https://git.yoctoproject.org/git/poky"
    commit: 89e6c98d92887913cadf06b2adb97f26cde4849b
    layers:
      # If `kas-poky.yml` adds the `meta-yocto-bsp` layer and we
      # do not want it in our bblayers for this project, we can
      # overwrite it by setting:
      meta-yocto-bsp: excluded

The files are addressed relative to the git repository path.

The include mechanism collects and merges the content from top to bottom and depth first. That means that settings in one include file are overwritten by settings in a latter include file and entries from the last include file can be overwritten by the current file. While merging all the dictionaries are merged recursively while preserving the order in which the entries are added to the dictionary. This means that local_conf_header entries are added to the local.conf file in the same order in which they are defined in the different include files. The header.version property is always set to the highest version number found in the config files.

Including configuration files via the command line

When specifying the kas configuration file on the command line, additional configurations can be included ad-hoc:

$ kas build kas-base.yml:debug-image.yml:board.yml

This is equivalent to static inclusion from some kas-combined.yml like this:

header:
  version: x
  includes:
    - kas-base.yml
    - debug.image.yml
    - board.yml

Command line inclusion allows one to create configurations on-demand, without the need to write a kas configuration file for each possible combination.

All configuration files combined via the command line either have to come from the same repository or have to live outside of any versioning control. kas will refuse any other combination in order to avoid complications and configuration flaws that can easily emerge from them.

Note

Git submodules are considered to be part of the main repository. Hence, including config files from a submodule is supported. The repository root is always the root of the main repository (if under VCS) or the directory of the first kas config file otherwise.

Working with lockfiles

kas supports the use of lockfiles to pinpoint repositories to exact commit ID (e.g. SHA-1 refs for git). A lockfile hereby only overrides the commit ID defined in a kas file. When performing the checkout operation (or any other operation that performs a checkout), kas checks if a file named <filename>.lock.<ext> is found next to the currently processed kas file. If this is found, kas loads this file right after processing the current one. Note, that this applies to both files on the kas cmdline, as well as included files.

The following example shows this mechanism for a file kas/kas-isar.yml and its corresponding lockfile kas/kas-isar.lock.yml.

kas/kas-isar.yml:

# [...]
repos:
  isar:
    url: https://github.com/ilbers/isar.git
    branch: next

kas/kas-isar.lock.yml:

header:
  version: 14
overrides:
  repos:
    isar:
      commit: 0336610df8bb0adce76ef8c5a921c758efed9f45

The lock plugin provides helpers to simplify the creation and update of lockfiles. For details, see the plugins documentation: kas.plugins.lock.

Configuration reference

header: dict [required]

Header of every kas configuration file. It contains information about the context of the file.

version: integer [required]

Version of the configuration file format. See the configuration format changelog for the format history and the latest available version.

includes: list [optional]

List of configuration files to include (parsed depth-first). They are merged in order they are stated. So a latter one could overwrite settings from previous files. The current file can overwrite settings from every included file. An item in this list can have one of two types:

item: string

Path to a kas configuration file, relative to the repository root of the current file.

item: dict

If files from other repositories should be included, choose this (dict) representation.

repo: string [required]: Repository key the configuration file is located in. The repo needs to be defined in the repos dictionary as <repo-id>.
file: string [required]: Path to the configuration file relative to the repository.

build_system: string [optional]

Defines the bitbake-based build system.

Supported values: openembedded, oe, isar

Known build systems are openembedded (or oe) and isar. If set, this restricts the search of kas for the init script in the configured repositories to oe-init-build-env or isar-init-build-env, respectively. If kas-container finds this property in the top-level kas configuration file (includes are not evaluated), it will automatically select the required container image and invocation mode.

defaults: dict [optional]

Default values applied to all configuration nodes. This may help you to avoid repeating the same property assignment in multiple places if, for example, you wish to use the same branch for all repositories.

repos: dict [optional]

Default values for some repository properties. If a default value is set for a repository property it may still be overridden by setting the same property to a different value in a given repository.

branch: string [optional]

Default branch property applied to all repositories that do not override this.

tag: string [optional]

Default tag property applied to all repositories that do not override this.

patches: dict [optional]

Default patches to apply to all repositories. If a default value is set for a patch property it may still be overridden by setting the same property to a different value in a given patch.

repo: string [optional]: Sets the default repo property applied to all repository patches that do not override this.

machine: string [optional]

Value of the MACHINE variable that is written into the local.conf. Can be overwritten by the KAS_MACHINE environment variable.

Default: qemux86-64

distro: string [optional]

Value of the DISTRO variable that is written into the local.conf. Can be overwritten by the KAS_DISTRO environment variable.

Default: poky

target: string [optional] or list [optional]

Single target or a list of targets to build by bitbake. Can be overwritten by the KAS_TARGET environment variable. Space is used as a delimiter if multiple targets should be specified via the environment variable. For targets prefixed with multiconfig: or mc:, corresponding entries are added to the BBMULTICONFIG in local.conf.

Default: core-image-minimal

env: dict [optional]

Environment variables to forward and their default values (set to nulltype to only forward if set). These variables are made available to bitbake via BB_ENV_PASSTHROUGH_ADDITIONS (BB_ENV_EXTRAWHITE in older Bitbake versions) and can be overwritten by the variables of the environment in which kas is started. Either a string or nothing (null) can be assigned as value. The former one serves as a default value whereas the latter one will lead to add the variable only to BB_ENV_PASSTHROUGH_ADDITIONS and not to the environment where kas is started. Please note, that null needs to be assigned as the nulltype (e.g. MYVAR: null), not as ‘null’.

task: string [optional]

Task to build by bitbake. Can be overwritten by the KAS_TASK environment variable.

Default: build

repos: dict [optional]

Definitions of all available repos and layers. The layers are appended to the bblayers.conf sorted by the repository name first and then by the layer name.

<repo-id>: dict [optional]

Definition of a repository and the layers, that should be part of the build. If the value is None, the repository, where the current configuration file is located is defined as <repo-id> and added as a layer to the build. It is recommended that the <repo-id> is related to the containing repository/layer to ease cross-project referencing.

name: string [optional]

Defines under which name the repository is stored. If its missing the <repo-id> will be used.

url: string [optional]

Url of the repository. If this is missing, no version control operations are performed.

type: string [optional]

Type of version control repository.

Default: git

Supported values: git, hg

commit: string [optional]

Full-length commit ID (all-lowercase, no branch names, no symbolic refs, no tags) that should be used. If url was specified but no commit, branch or tag, the revision you get depends on the defaults of the version control system used.

branch: string or nothing (null) [optional]

Upstream branch that should be tracked. If commit was specified, kas checks that the branch contains the commit. If no commit was specified, the head of the upstream branch is checked out. The nothing (null) value is used to remove a possible default value.

tag: string or nothing (null) [optional]

Tag that should be checked out. If a commit was specified, kas checks that the tag points to this commit. This must not be combined with branch. The nothing (null) value is used to remove a possible default value.

path: string [optional]

Path where the repository is stored. If the url and path is missing, the repository where the current configuration file is located is defined. If the url is missing and the path defined, this entry references the directory the path points to. If the url as well as the path is defined, the path is used to overwrite the checkout directory, that defaults to kas_work_dir + repo.name. In case of a relative path name kas_work_dir is prepended.

layers: dict [optional]

List of layers to append to the bblayers.conf. If this is missing or None or an empty dictionary, the path to the repo itself is added as a layer. Additionally, . is a valid value if the repo itself should be added as a layer. This allows combinations:

repos:
  meta-foo:
    url: https://github.com/bar/meta-foo.git
    path: layers/meta-foo
    branch: master
    layers:
      .:
      contrib:

This adds both layers/meta-foo and layers/meta-foo/contrib from the meta-foo repository to bblayers.conf.

<layer-path>: enum [optional]: Adds the layer with <layer-path> that is relative to the repository root directory, to the bblayers.conf if the value of this entry is not in this list: ['disabled', 'excluded', 'n', 'no', '0', 'false']. This way it is possible to overwrite the inclusion of a layer in latter loaded configuration files.

patches: dict [optional]

Patches to apply to the repository.

<patches-id>: dict [optional]

One entry in patches with its specific and unique id. All available patch entries are applied in the order of their sorted <patches-id>.

repo: string [required]: The identifier of the repo where the path of this entry is relative to.
path: string [required]: The path to one patch file or a quilt formatted patchset directory.

overrides: dict [optional]

Overrides for specific configuration nodes. By that, only items that already exist are overridden. Note, that all entries below this key are reserved for auto-generation using kas plugins. Do not manually add entries.

repos: dict [optional]

Mapps to the top-level repos entry.

<repo-id>: dict [optional]: Mapps to the <repo-id> entry.
commit: string [optional]: Pinned commit ID which overrides the commit of the corresponding repo.

bblayers_conf_header: dict [optional]

Header to prepend to the bblayers.conf before any layers are included.

<bblayers-conf-id>: string [optional]: A string that is added to the bblayers.conf. The entry id (<bblayers-conf-id>) should be unique if lines should be added and can be the same from another included file, if this entry should be overwritten. The lines are added to bblayers.conf in alphabetic order of <bblayers-conf-id> to ensure deterministic generation of config files.

local_conf_header: dict [optional]

Header to prepend to the local.conf.

<local-conf-id>: string [optional]: A string that is added to the local.conf. It operates in the same way as the bblayers_conf_header entry.

menu_configuration: dict [optional]

Menu configuration, auto-generated by menu plugin. Each variable corresponds to a Kconfig configuration variable and can be of the types string, boolean or integer. The content of this key is typically maintained by the kas menu plugin in a .config.yaml file.

artifacts: dict [optional]

Artifacts which are expected to be present after executing the build (id / path pairs). Each key-value pair describes an identifier and a path relative to the kas build dir, whereby the path can contain wildcards like *. Unix-style globbing is applied to all paths. In case no artifact is found, the build is considered successful, if not stated otherwise by the used plugin and mode of operation.

Note

There are no further semantics attached to the identifiers (yet). Both the author and the consumer of the artifacts node need to agree on the semantics.

Example:

artifacts:
  disk-image: path/to/image.*.img
  firmware: path/to/firmware.bin
  swu: path/to/update.swu

_source_dir: string [optional]

Path to the top repo at time of invoking the plugin (auto-generated by the menu plugin). It must not be set manually and might only be defined in the top-level .config.yaml file.

_source_dir_host: string [optional]

Source directory of the config file on the host (auto-generated by kas menu plugin, when using kas-container). It provides the absolute path to the top repo outside of the container (on the host). This value is only evaluated by the kas-container script. It must not be set manually and might only be defined in the top-level .config.yaml file.

Example project configurations

The following snippets show minimal but working project configurations for both OpenEmbedded and ISAR based distributions.

OpenEmbedded

header:
  version: 14

machine: qemux86-64
distro: poky

target: zlib-native

repos:
  poky:
    url: https://git.yoctoproject.org/poky.git
    commit: fb91a49387cfb0c8d48303bb3354325ba2a05587
    layers:
      meta:
      meta-poky:

ISAR

header:
  version: 14

build_system: isar

machine: qemuamd64
distro: debian-bullseye

target: mc:qemuamd64-bullseye:cowsay

repos:
  isar:
    url: https://github.com/ilbers/isar.git
    commit: 9dc362cd7115074c0f60843e687ed89db5c9339a
    layers:
      meta:
      meta-isar: