29027fd1e1
Using pkgs.lib on the spine of module evaluation is problematic because the pkgs argument depends on the result of module evaluation. To prevent an infinite recursion, pkgs and some of the modules are evaluated twice, which is inefficient. Using ‘with lib’ prevents this problem.
102 lines
2.9 KiB
Nix
102 lines
2.9 KiB
Nix
{ config, lib, pkgs, modules, ... }:
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with lib;
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let
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# Location of the repository on the harddrive
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nixosPath = toString ../..;
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# Check if the path is from the NixOS repository
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isNixOSFile = path:
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let s = toString path; in
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removePrefix nixosPath s != s;
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# Copy modules given as extra configuration files. Unfortunately, we
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# cannot serialized attribute set given in the list of modules (that's why
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# you should use files).
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moduleFiles =
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# FIXME: use typeOf (Nix 1.6.1).
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filter (x: !isAttrs x && !builtins.isFunction x) modules;
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# Partition module files because between NixOS and non-NixOS files. NixOS
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# files may change if the repository is updated.
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partitionedModuleFiles =
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let p = partition isNixOSFile moduleFiles; in
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{ nixos = p.right; others = p.wrong; };
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# Path transformed to be valid on the installation device. Thus the
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# device configuration could be rebuild.
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relocatedModuleFiles =
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let
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relocateNixOS = path:
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"<nixos" + removePrefix nixosPath (toString path) + ">";
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relocateOthers = null;
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in
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{ nixos = map relocateNixOS partitionedModuleFiles.nixos;
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others = []; # TODO: copy the modules to the install-device repository.
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};
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# A dummy /etc/nixos/configuration.nix in the booted CD that
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# rebuilds the CD's configuration (and allows the configuration to
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# be modified, of course, providing a true live CD). Problem is
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# that we don't really know how the CD was built - the Nix
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# expression language doesn't allow us to query the expression being
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# evaluated. So we'll just hope for the best.
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configClone = pkgs.writeText "configuration.nix"
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''
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{ config, pkgs, ... }:
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{
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imports = [ ${toString config.installer.cloneConfigIncludes} ];
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}
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'';
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in
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{
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options = {
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installer.cloneConfig = mkOption {
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default = true;
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description = ''
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Try to clone the installation-device configuration by re-using it's
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profile from the list of imported modules.
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'';
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};
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installer.cloneConfigIncludes = mkOption {
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default = [];
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example = [ "./nixos/modules/hardware/network/rt73.nix" ];
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description = ''
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List of modules used to re-build this installation device profile.
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'';
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};
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};
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config = {
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installer.cloneConfigIncludes =
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relocatedModuleFiles.nixos ++ relocatedModuleFiles.others;
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boot.postBootCommands =
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''
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# Provide a mount point for nixos-install.
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mkdir -p /mnt
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${optionalString config.installer.cloneConfig ''
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# Provide a configuration for the CD/DVD itself, to allow users
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# to run nixos-rebuild to change the configuration of the
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# running system on the CD/DVD.
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if ! [ -e /etc/nixos/configuration.nix ]; then
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cp ${configClone} /etc/nixos/configuration.nix
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fi
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''}
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'';
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};
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}
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