The RootFS configuration.yml file

This file resides in the in the root directory of the rootfs-Repository. The file is written in YAML-Syntax. The --- in the first line of the file is necessary syntax which indicates YAML-files, and must not be removed.

To demonstrate a minimal working example this guide provides a slimmed down version of the systemd-rootfs specification taken from the actual setup at the HTWG.

Global Flags Section

The global-Section configures the settings for global USE-Flags and keywords, which apply for every installed package. If you find yourself putting the same keywords or USE-flags for every package, this is the place to put them instead.

---
global:
    use:
        +: "python"
        -: "X doc"

The USE-flags X and doc are disabled system-wide, causing all affected packages to build without X-support and without the installation of additional documentation. The python-flag will be enabled for every package that supports it. For example, this might cause packages to be built with bindings for Python activated.

Package-List and Package-Flags Section

The global section is followed by the package list. It is a YAML-dictionary which defines the packages that are to be installed in the RootFS. The syntax for every package is the same as for the global system.

packages:
    sys-apps/util-linux:
        use:
            -: "systemd"
    virtual/udev:
        kw:
            +: "~amd64 ~x86"
    sys-apps/systemd:
        kw:
            +: "~amd64 ~x86"
        use: 
            +: "importd gcrypt curl lz4 lzma"
    app-editors/vim: {}

The example shows the packages sys-apps/util-linux, virtual/udev, sys-apps/systemd and app-editors/vim to be installed, with different configuration. The brackets after the vim-line define an empty dictionary, which cause the package to be installed with the default options. Remember, that the default options are also influenced by the global-Section.

Pre/Post-Install Commands Section

In order to not be limited to installing packages, or sometimes to work around problems that occur during package installation, you can also specifi commands that are run before and after the package installation. Both are specified as a list of strings, which could look like in the following example.

pre_install_commands:
    - "emerge --sync"
    - "chown -R portage:portage /usr/portage"

post_install_commands:
    - "echo Europe/Berlin > /etc/timezone"
    - "emerge --config timezone-data"
    - "mv /sbin/init /sbin/init-openrc"
    - "ln -sf /usr/lib/systemd/systemd /sbin/init"

You can specify any command here. They will be run as root in sequential order in the target RootFS. The changes you make with your commands are not persistent to your next build job and will therefore only take effect for the current build.