snap and mount separation

This commit is contained in:
Joseph Hanson 2025-01-04 19:17:53 -06:00
parent b181efdb41
commit 4f5c090534
4 changed files with 120 additions and 130 deletions

View file

@ -18,7 +18,48 @@ let
];
text = ''
${builtins.readFile ./snap-and-mount.sh} "${cfg.mountPath}" "${cfg.zfsDataset}" "${cfg.snapshotName}"
# Import our functions
${builtins.readFile ./functions.sh}
BACKUP_DIRECTORY="${cfg.mountPath}"
ZFS_DATASET="${cfg.zfsDataset}"
SNAPSHOT_NAME="${cfg.snapshotName}"
if [ "$(id -u)" -ne 0 ]; then
echo "Error: This script must be run as root."
exit 1
fi
# Main logic
zfs_backup_cleanup "$BACKUP_DIRECTORY"
echo "Previous snapshot:"
zfs list -t snapshot | grep "$ZFS_DATASET@$SNAPSHOT_NAME" || true
echo "Attempting to destroy existing snapshot..."
if zfs destroy -r "$ZFS_DATASET@$SNAPSHOT_NAME"; then
echo "Successfully destroyed old snapshot"
else
echo "Failed to destroy existing snapshot"
exit 1
fi
# Create new snapshot
if ! zfs snapshot -r "$ZFS_DATASET@$SNAPSHOT_NAME"; then
echo "Failed to create snapshot"
exit 1
fi
echo "New snapshot created:"
zfs list -t snapshot | grep "$ZFS_DATASET@$SNAPSHOT_NAME"
if ! mount_dataset; then
echo "Failed to mount snapshot"
exit 1
fi
echo "Successfully created and mounted snapshot at $BACKUP_DIRECTORY"
mount | grep "$BACKUP_DIRECTORY"
'';
};
in

View file

@ -0,0 +1,68 @@
#!/usr/bin/env bash
# functions sourced from: https://github.com/Jip-Hop/zfs-backup-snapshots
function mount_dataset() {
mkdir -p "$BACKUP_DIRECTORY"
mapfile -t fs < <(zfs list "$ZFS_DATASET" -r -H -o name,mountpoint | grep -E "(legacy)$|(none)$" -v | awk '{print gsub("/","/", $2), $1}' | sort -n | cut -d' ' -f2-)
for fs in "${fs[@]}"; do
mount_latest_snap "${fs}" "${BACKUP_DIRECTORY}"
done
return 0
}
function zfs_backup_cleanup() {
mapfile -t fs < <(tac /etc/mtab | cut -d " " -f 2 | grep "${1}")
for i in "${fs[@]}"; do
echo "Unmounting $i"
umount "$i"
done
find "${1}" -type d -empty -delete 2>/dev/null || true
}
function zfs_latest_snap() {
snapshot=$(zfs list -H -t snapshot -o name -S creation -d1 "${1}" | head -1 | cut -d '@' -f 2)
if [[ -z $snapshot ]]; then
echo "No snapshot exists for ${1}, it will not be backed up."
return 1
fi
echo "$snapshot"
}
function zfs_snapshot_mountpoint() {
mountpoint=$(zfs list -H -o mountpoint "${1}")
if [[ $? == 1 ]]; then
return 1
fi
path="${mountpoint}/.zfs/snapshot/${2}"
if stat "${path}" &>/dev/null; then
echo "${path}"
return 0
else
return 1
fi
}
function mount_latest_snap() {
BACKUP_DIRECTORY="${2}"
filesystem="${1}"
snapshot=$(zfs_latest_snap "${filesystem}")
if [[ $? == 1 ]]; then
return 1
fi
sourcepath=$(zfs_snapshot_mountpoint "${filesystem}" "${snapshot}")
if [[ $? == 1 ]]; then
echo "Cannot find snapshot ${snapshot} for ${filesystem}, perhaps it's not mounted?"
return 1
fi
mountpath=${BACKUP_DIRECTORY}/${filesystem}
mkdir -p "${mountpath}"
echo "mount ${sourcepath} => ${mountpath}"
mount --bind --read-only "${sourcepath}" "${mountpath}"
return 0
}

View file

@ -1,15 +0,0 @@
#!/usr/bin/env nix-shell
#!nix-shell -I nixpkgs=/etc/nix/inputs/nixpkgs -i bash -p busybox zfs
# shellcheck disable=SC1008
set -e # Exit on error
BACKUP_DIRECTORY="/mnt/restic_nightly_backup"
ZFS_DATASET="nahar/containers/volumes"
SNAPSHOT_NAME="restic_nightly_snap"
# Execute the main script with our parameters
./snap-and-mount.sh \
"$BACKUP_DIRECTORY" \
"$ZFS_DATASET" \
"$SNAPSHOT_NAME"

View file

@ -1,129 +1,27 @@
#!/usr/bin/env nix-shell
#!nix-shell -I nixpkgs=/etc/nix/inputs/nixpkgs -i bash -p busybox zfs
# shellcheck disable=SC1008
# Command line arguments
BACKUP_DIRECTORY="$1"
ZFS_DATASET="$2"
SNAPSHOT_NAME="$3"
set -e # Exit on error
if [ -z "$BACKUP_DIRECTORY" ] || [ -z "$ZFS_DATASET" ] || [ -z "$SNAPSHOT_NAME" ]; then
echo "Usage: $0 <backup_directory> <zfs_dataset> <snapshot_name>"
exit 1
fi
# Check if running as root
# Source the functions
. ./functions.sh
BACKUP_DIRECTORY="${1:-/mnt/restic_nightly_backup}"
ZFS_DATASET="${2:-nahar/containers/volumes}"
SNAPSHOT_NAME="${3:-restic_nightly_snap}"
if [ "$(id -u)" -ne 0 ]; then
echo "Error: This script must be run as root."
exit 1
fi
# functions sourced from: https://github.com/Jip-Hop/zfs-backup-snapshots
# some enhancements made to the original code to adhere to best practices
# mounts all zfs filesystems under $ZFS_DATASET
function mount_dataset() {
# ensure BACKUP_DIRECTORY exists
mkdir -p "$BACKUP_DIRECTORY"
# get list of all zfs filesystems under $ZFS_DATASET
# exclude if mountpoint "legacy" and "none" mountpoint
# order by shallowest mountpoint first (determined by number of slashes)
mapfile -t fs < <(zfs list "$ZFS_DATASET" -r -H -o name,mountpoint | grep -E "(legacy)$|(none)$" -v | awk '{print gsub("/","/", $2), $1}' | sort -n | cut -d' ' -f2-)
for fs in "${fs[@]}"; do
mount_latest_snap "${fs}" "${BACKUP_DIRECTORY}"
done
return 0
}
# umounts and cleans up the backup directory
# usage: zfs_backup_cleanup BACKUP_DIRECTORY
function zfs_backup_cleanup() {
# get all filesystems mounted within the backup directory
mapfile -t fs < <(tac /etc/mtab | cut -d " " -f 2 | grep "${1}")
# umount said filesystems
for i in "${fs[@]}"; do
echo "Unmounting $i"
umount "$i"
done
# delete empty directories from within the backup directory
find "${1}" -type d -empty -delete 2>/dev/null || true
}
# gets the name of the newest snapshot given a zfs filesystem
# usage: get_latest_snap filesystem
function zfs_latest_snap() {
snapshot=$(zfs list -H -t snapshot -o name -S creation -d1 "${1}" | head -1 | cut -d '@' -f 2)
if [[ -z $snapshot ]]; then
# if there's no snapshot then let's ignore it
echo "No snapshot exists for ${1}, it will not be backed up."
return 1
fi
echo "$snapshot"
}
# gets the path of a snapshot given a zfs filesystem and a snapshot name
# usage zfs_snapshot_mountpoint filesystem snapshot
function zfs_snapshot_mountpoint() {
# get mountpoint for filesystem
mountpoint=$(zfs list -H -o mountpoint "${1}")
# exit if filesystem doesn't exist
if [[ $? == 1 ]]; then
return 1
fi
# build out path
path="${mountpoint}/.zfs/snapshot/${2}"
# check to make sure path exists
if stat "${path}" &>/dev/null; then
echo "${path}"
return 0
else
return 1
fi
}
# mounts latest snapshot in directory
# usage: mount_latest_snap filesystem BACKUP_DIRECTORY
function mount_latest_snap() {
BACKUP_DIRECTORY="${2}"
filesystem="${1}"
# get name of latest snapshot
snapshot=$(zfs_latest_snap "${filesystem}")
# if there's no snapshot then let's ignore it
if [[ $? == 1 ]]; then
echo "No snapshot exists for ${filesystem}, it will not be backed up."
return 1
fi
sourcepath=$(zfs_snapshot_mountpoint "${filesystem}" "${snapshot}")
# if the filesystem is not mounted/path doesn't exist then let's ignore as well
if [[ $? == 1 ]]; then
echo "Cannot find snapshot ${snapshot} for ${filesystem}, perhaps it's not mounted? Anyways, it will not be backed up."
return 1
fi
# mountpath may be inside a previously mounted snapshot
mountpath=${BACKUP_DIRECTORY}/${filesystem}
# mount to backup directory using a bind filesystem
mkdir -p "${mountpath}"
echo "mount ${sourcepath} => ${mountpath}"
mount --bind --read-only "${sourcepath}" "${mountpath}"
return 0
}
# Unmount and cleanup if necessary
# Main logic
zfs_backup_cleanup "$BACKUP_DIRECTORY"
# Check if snapshot exists
echo "Previous snapshot:"
zfs list -t snapshot | grep "$ZFS_DATASET@$SNAPSHOT_NAME" || true
# Attempt to destroy existing snapshot
echo "Attempting to destroy existing snapshot..."
if zfs destroy -r "$ZFS_DATASET@$SNAPSHOT_NAME"; then
echo "Successfully destroyed old snapshot"
@ -132,7 +30,6 @@ else
exit 1
fi
# Create new snapshot
if ! zfs snapshot -r "$ZFS_DATASET@$SNAPSHOT_NAME"; then
echo "Failed to create snapshot"
exit 1
@ -141,7 +38,6 @@ fi
echo "New snapshot created:"
zfs list -t snapshot | grep "$ZFS_DATASET@$SNAPSHOT_NAME"
# Mount the snapshot
if ! mount_dataset; then
echo "Failed to mount snapshot"
exit 1