Empaquetado de Configuración por Producto

In the Fedora.next world, we have a set of curated Fedora Products as well as the availability of classic Fedora. Historically, we have maintained a single set of configuration defaults for all Fedora installs, but different target use-cases have different needs. The goal of this document is to set out the guidelines for creating per-Product configuration defaults.

Queremos garantizar que todos los paquetes tengan valores predeterminados razonables para cualquier Producto en el que estén instalados, y al mismo tiempo evitar situaciones donde los usuarios tengan algunos paquetes instalados con los valores predeterminados de un Producto y algunos paquetes con los de otro.

Requisitos

  • All packages MUST have a global default configuration. This configuration will be used whenever a Product-specific default configuration is not required. (For example, if a non-Product install is in use or only Fedora Cloud has a custom configuration and Fedora Workstation was installed).

  • Any package that requires a per-product default configuration MUST provide all alternate configuration files in the same package.

  • Any package that requires a configuration that differs between Products MUST obtain permission from that Product’s Working Group before packaging it.

Configuración Predeterminada Global

  • The global default configuration MUST be provided by the package that requires it.

  • The global default configuration MUST be named based on the package’s normal naming scheme, with the main part of the name being suffixed by -default. For example, if the package normally uses foo.conf, then the global default configuration MUST be named foo-default.conf.

Per-Product Default Configuration

  • For each Product requiring a unique default configuration, the packager MUST provide a copy of the default configuration file, modified as appropriate for the specific product.

  • The product-specific configuration file MUST be named based on the package’s normal naming scheme, with the main part of the name being suffixed by a dash followed by the name of the product. For example, if the package normally uses foo.conf, then the Server version MUST be named foo-server.conf.

  • If the configuration will be symlinked in place, the product-specific configuration file MUST be located in an appropriate part of the /etc hierarchy. The divergent config file MUST be specified as %config(noreplace) in %files as per the usual /etc packaging guidelines.

  • If the configuration will be copied in place, the product-specific configuration file MUST be located in an appropriate part of the /usr/share hierarchy. The divergent config file MUST be specified as a normal file in the %files section.

Applying Configuration

In order to apply the configuration, the packager MUST implement a mechanism in the %posttrans section of the specfile that behaves as follows:

  • It MUST first check whether the final config file already exists. If so, the script MUST make no changes.

    %posttrans
    if [ ! -e %{_sysconfdir}/foo/foo.conf ]; then
        ...
    fi
  • Then it MUST use the value of the Fedora VARIANT_ID to symlink or copy one of the divergent config files (or the default) to the final config file location. It will get this value by importing the contents of /etc/os-release as shell values. Known values of this field at the time of this writing are "atomichost", "cloud", "server" and "workstation". For more detail, see the os-release(5) man page.

    . /etc/os-release || :
    case "$VARIANT_ID" in
        server)
            ln -sf foo-server.conf %{_sysconfdir}/foo/foo.conf || :
            ;;
        *)
            ln -sf foo-default.conf %{_sysconfdir}/foo/foo.conf || :
            ;;
        esac
  • Lastly, the final config file location MUST be listed in the %files section with %ghost:

    %ghost %config(noreplace) %{_sysconfdir}/foo/foo.conf
  • For tracking purposes, the package providing the various configuration files MUST also contain a virtual Provides: for each variant configuration that may be applied:

    Provides: variant_config(Atomic.host)
    Provides: variant_config(Cloud)
    Provides: variant_config(Server)
    Provides: variant_config(Workstation)

Ejemplo (firewalld)

We will assume for the sake of demonstration that firewalld will need a custom configuration for Fedora Server and Fedora Workstation, but that Fedora Cloud will not require any changes from the global default.

...
Provides: variant_config(Server)
Provides: variant_config(Workstation)
...

%posttrans
# If we don't yet have a symlink or existing file for firewalld.conf,
# create it. Note: this will intentionally reset the policykit policy
# at the same time, so they are in sync.
if [ ! -e %{_sysconfdir}/firewalld/firewalld.conf ]; then
    # Import /etc/os-release to get the variant definition
    . /etc/os-release || :

    case "$VARIANT_ID" in
        server)
            ln -sf firewalld-server.conf %{_sysconfdir}/firewalld/firewalld.conf || :
            ln -sf org.fedoraproject.FirewallD1.server.policy \
                %{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.policy || :
            ;;
        workstation)
            ln -sf firewalld-workstation.conf %{_sysconfdir}/firewalld/firewalld.conf || :
            ln -sf org.fedoraproject.FirewallD1.desktop.policy \
                %{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.policy || :
            ;;
        *)
            ln -sf firewalld-default.conf %{_sysconfdir}/firewalld/firewalld.conf || :
            # La normativa de cortafuegos predeterminada será la misma que la del servidor.
            ln -sf org.fedoraproject.FirewallD1.server.policy \
                %{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.policy || :
            ;;
        esac
fi

…

%files -f %{name}.lang
…
%attr(0750,root,root) %dir %{_sysconfdir}/firewalld
%ghost %config(noreplace) %{_sysconfdir}/firewalld/firewalld.conf
%config(noreplace) %{_sysconfdir}/firewalld/firewalld-default.conf
%config(noreplace) %{_sysconfdir}/firewalld/firewalld-server.conf
%config(noreplace) %{_sysconfdir}/firewalld/firewalld-workstation.conf
…
%ghost %{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.policy
%{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.desktop.policy
%{_datadir}/polkit-1/actions/org.fedoraproject.FirewallD1.server.policy