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make-ext4-fs: Allows populating with custom files

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This will allow adding /boot files to the rootfs.
This commit is contained in:
Samuel Dionne-Riel 2019-06-01 21:06:03 -04:00
parent 6e9e78b618
commit a0aff40f65
1 changed files with 20 additions and 5 deletions
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25
nixos/lib/make-ext4-fs.nix
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@ -1,9 +1,14 @@
# Builds an ext4 image containing a populated /nix/store with the closure
# of store paths passed in the storePaths parameter. The generated image
# is sized to only fit its contents, with the expectation that a script
# resizes the filesystem at boot time.
# of store paths passed in the storePaths parameter, in addition to the
# contents of a directory that can be populated with commands. The
# generated image is sized to only fit its contents, with the expectation
# that a script resizes the filesystem at boot time.
{ pkgs
# List of derivations to be included
, storePaths
# Shell commands to populate the ./files directory.
# All files in that directory are copied to the root of the FS.
, populateImageCommands ? ""
, volumeLabel
, uuid ? "44444444-4444-4444-8888-888888888888"
, e2fsprogs
@ -23,13 +28,17 @@ pkgs.stdenv.mkDerivation {
buildCommand =
''
(
mkdir -p ./files
${populateImageCommands}
)
# Add the closures of the top-level store objects.
storePaths=$(cat ${sdClosureInfo}/store-paths)
# Make a crude approximation of the size of the target image.
# If the script starts failing, increase the fudge factors here.
numInodes=$(find $storePaths | wc -l)
numDataBlocks=$(du -c -B 4096 --apparent-size $storePaths | awk '$2 == "total" { print int($1 * 1.03) }')
numInodes=$(find $storePaths ./files | wc -l)
numDataBlocks=$(du -s -c -B 4096 --apparent-size $storePaths ./files | tail -1 | awk '{ print int($1 * 1.03) }')
bytes=$((2 * 4096 * $numInodes + 4096 * $numDataBlocks))
echo "Creating an EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks)"
@ -47,6 +56,12 @@ pkgs.stdenv.mkDerivation {
echo "copying store paths to image..."
cptofs -t ext4 -i $out $storePaths /nix/store/
(
echo "copying files to image..."
cd ./files
cptofs -t ext4 -i $out ./* /
)
# I have ended up with corrupted images sometimes, I suspect that happens when the build machine's disk gets full during the build.
if ! fsck.ext4 -n -f $out; then
echo "--- Fsck failed for EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks) ---"