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image builder: integrate impermanence so that we create such things as /var/log

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untested
This commit is contained in:
colin 2022-08-01 14:37:19 -07:00
parent 8ae0d77938
commit 1a9dfe22ba
2 changed files with 10 additions and 11 deletions
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20
modules/image.nix
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@ -12,6 +12,12 @@ in
default = [];
type = types.listOf types.package;
};
# extra (empty) directories to create in the rootfs.
# for example, /var/log might be required by the boot process, so ensure it exists.
sane.image.extraDirectories = mkOption {
default = [];
type = types.listOf types.str;
};
# the GPT header is fixed to Logical Block Address 1,
# but we can actually put the partition entries anywhere.
@ -46,6 +52,7 @@ in
(builtins.substring 0 (builtins.stringLength sub) super) == sub
);
# return the (string) path to get from `stem` to `path`
# XXX: not sure how this behaves if the path doesn't contain the stem.
relPath = stem: path: (
builtins.head (builtins.match "^${stem}(.+)" path)
);
@ -56,14 +63,6 @@ in
# resolves to e.g. "nix/store", "/store" or ""
storeRelPath = relPath nixFs.mountPoint "/nix/store";
# return a list of all the `device` values -- one for each fileSystems."$x"
devices = builtins.attrValues (builtins.mapAttrs (mount: entry: entry.device) fileSystems);
# filter the devices to just those which sit under nixFs
subNixMounts = builtins.filter (a: startsWith (builtins.toString a) nixFs.mountPoint) devices;
# e.g. ["/nix/persist/var"] -> ["/persist/var"] if nixFs sits at /nix
subNixRelMounts = builtins.map (m: relPath nixFs.mountPoint m) subNixMounts;
makeSubNixMounts = builtins.toString (builtins.map (m: "mkdir -p ./${m};") subNixRelMounts);
uuidFromFs = fs: builtins.head (builtins.match "/dev/disk/by-uuid/(.+)" fs.device);
vfatUuidFromFs = fs: builtins.replaceStrings ["-"] [""] (uuidFromFs fs);
@ -113,11 +112,10 @@ in
populateCommands =
let
closureInfo = buildPackages.closureInfo { rootPaths = config.system.build.toplevel; };
extraRelPaths = builtins.map (p: relPath nixFs.mountPoint m) cfg.extraDirectories;
in
''
mkdir -p ./${storeRelPath}
# TODO: we should create the dirs required for boot (/var/log?). the rest are populated automatically.
# $(makeSubNixMounts)
mkdir -p ./${storeRelPath} ${extraRelPaths}
echo "Copying system closure..."
while IFS= read -r path; do
echo " Copying $path"

1
modules/impermanence.nix
View File

@ -36,6 +36,7 @@ in
map-sys-dirs = map-dirs { user = "root"; group = "root"; mode = "0755"; directory = ""; };
map-service-dirs = map-dirs { user = "root"; group = "root"; mode = "0755"; directory = ""; };
in mkIf cfg.enable {
sane.image.extraDirectories = [ "/nix/persist/var/log" ];
environment.persistence."/nix/persist" = {
directories = (map-home-dirs ([
# cache is probably too big to fit on the tmpfs