fee76f189c
I wrote this up when I was playing with a btrfs sd card, and figured that it would be useful for others.
46 lines
1.3 KiB
Nix
46 lines
1.3 KiB
Nix
# Builds an btrfs image containing a populated /nix/store with the closure
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# of store paths passed in the storePaths parameter, in addition to the
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# contents of a directory that can be populated with commands. The
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# generated image is sized to only fit its contents, with the expectation
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# that a script resizes the filesystem at boot time.
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{ pkgs
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, lib
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# List of derivations to be included
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, storePaths
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# Shell commands to populate the ./files directory.
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# All files in that directory are copied to the root of the FS.
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, populateImageCommands ? ""
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, volumeLabel
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, uuid ? "44444444-4444-4444-8888-888888888888"
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, btrfs-progs
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}:
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let
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sdClosureInfo = pkgs.buildPackages.closureInfo { rootPaths = storePaths; };
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in
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pkgs.stdenv.mkDerivation {
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name = "btrfs-fs.img";
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nativeBuildInputs = [ btrfs-progs ];
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buildCommand =
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''
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set -x
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(
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mkdir -p ./files
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${populateImageCommands}
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)
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mkdir -p ./files/nix/store
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cp ${sdClosureInfo}/registration ./files/nix-path-registration
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# Add the closures of the top-level store objects.
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for p in $(cat ${sdClosureInfo}/store-paths); do
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echo cp -r $p "./files/nix/store"
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done
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touch $out
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mkfs.btrfs -L ${volumeLabel} -U ${uuid} -r ./files --shrink $out
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'';
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}
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