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try trap

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RingOfStorms (Joshua Bell) 2025-12-16 11:22:35 -06:00
parent 29e83501bf
commit 48946c2a1e
2 changed files with 36 additions and 19 deletions
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49
hosts/i001/hardware-mounts.nix
View file

@ -225,7 +225,7 @@ lib.mkMerge [
# TODO rotate root
}
# Reset root for erase your darlings/impermanence/preservation
(lib.mkIf false {
(lib.mkIf true {
boot.initrd.systemd.services.bcachefs-reset-root = {
description = "Reset bcachefs root subvolume before pivot";
@ -261,45 +261,56 @@ lib.mkMerge [
};
script = ''
# 1. Safety check: Try to see if we can read the device.
# If the unlock script failed (or user hasn't typed password yet), this mount will fail.
# We should probably exit non-zero to stop the boot or loop here?
# Actually, if we fail here, the boot continues to sysroot.mount, which will prompt for password,
# BUT we will have skipped the reset. This is a trade-off.
# 1. Enable Debugging
# This will print every command to the journal so you can see exactly where it fails
# View logs with: journalctl -u bcachefs-reset-root -b
set -x
# 2. Define Cleanup Trap
# This guarantees unmount runs even if the script crashes or fails halfway
cleanup() {
if mountpoint -q /primary_tmp; then
echo "Cleaning up: Unmounting /primary_tmp"
umount /primary_tmp
fi
}
trap cleanup EXIT
mkdir -p /primary_tmp
# Try mounting. If locked, this fails.
# 3. Mount
# If this fails, we exit 0 to allow the boot to proceed (skipping reset)
if ! mount "${PRIMARY}" /primary_tmp; then
echo "bcachefs-reset-root: Failed to mount ${PRIMARY}. Drive might be locked."
echo "Skipping root reset."
echo "Failed to mount ${PRIMARY}. Drive locked or unavailable."
exit 0
fi
# 2. Perform the Snapshot & Reset
# 4. Reset Logic
if [[ -e /primary_tmp/@root ]]; then
# Ensure parent dirs exist
mkdir -p /primary_tmp/@snapshots/old_roots
# Format: YYYY-MM-DD_HH:MM:SS
timestamp=$(date --date="@$(stat -c %Y /primary_tmp/@root)" "+%Y-%m-%-d_%H:%M:%S")
# Use safe date format (underscores instead of colons) to avoid filesystem quirks
timestamp=$(date --date="@$(stat -c %Y /primary_tmp/@root)" "+%Y-%m-%d_%H-%M-%S")
echo "Snapshotting old root to @snapshots/old_roots/$timestamp"
echo "Snapshotting @root to @snapshots/old_roots/$timestamp"
bcachefs subvolume snapshot /primary_tmp/@root "/primary_tmp/@snapshots/old_roots/$timestamp"
echo "Deleting current @root"
bcachefs subvolume delete /primary_tmp/@root
# Cleanup old snapshots (>30 days)
echo "Cleaning up old snapshots..."
find /primary_tmp/@snapshots/old_roots/ -maxdepth 1 -mtime +30 -print0 | xargs -0 -r -I {} sh -c 'echo "Deleting {}"; bcachefs subvolume delete "{}"'
# We use 'find' with -print0 and 'xargs -0 -r' to handle filenames safely
echo "Pruning old snapshots..."
find /primary_tmp/@snapshots/old_roots/ -maxdepth 1 -mtime +30 -print0 | \
xargs -0 -r -I {} sh -c 'echo "Deleting {}"; bcachefs subvolume delete "{}"'
fi
# 3. Create fresh root
echo "Creating fresh @root subvolume"
# 5. Create Fresh Root
echo "Creating empty @root subvolume"
bcachefs subvolume create /primary_tmp/@root
# 4. Cleanup
umount /primary_tmp
# Trap will handle the unmount automatically on exit
'';
};
})

6
utilities/nixos-installers/install_bcachefs.md
View file

@ -94,6 +94,12 @@ nixos-install --flake "git+https://git.joshuabell.xyz/ringofstorms/dotfiles?dir=
# nh os switch "git+https://git.joshuabell.xyz/ringofstorms/dotfiles?dir=hosts/i001#i001"
```
```sh
cd ~/.config
git clone https://git.joshuabell.xyz/ringofstorms/dotfiles nixos-config
cd ~/.config/nixos-config/hosts/i001
```
or from host machine? TODO haven't tried this fully
```sh