80 lines
2.4 KiB
Bash
80 lines
2.4 KiB
Bash
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#!/bin/bash
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set -e -o pipefail
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mkdir -p /backups
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chmod 750 /backups
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chown root:sudo /backups
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mkdir -p /snapshots
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chmod 700 /snapshots
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chown root:root /snapshots
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name=""
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clone_sources=()
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while (( $# > 0 )); do
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case "$1" in
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-n)
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name="$2"
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shift
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;;
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-c)
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clone_sources+=(-c "$2")
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shift
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;;
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*)
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cat <<EOF >&2
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usage: sudo $0 [-n <name-suffix>] [-c <clone-source-snapshot-name>]
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creates a encrypted backup of the btrfs subvolume mounted at '/' and uses all
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the '-c' options as clone source snapshots to reduce the size of the
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final file. see 'man btrfs-send' for details of how '-c' works.
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EOF
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exit 1
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;;
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esac
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shift
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done
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if [[ -n "$name" ]]; then
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name="-$name"
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fi
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name="snap-$(date --iso-8601=date -u)$name"
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echo "final base name: '$name'"
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if [[ "$1" =~ ^'-' ]]; then
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cat <<'EOF' >&2
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usage: sudo ./backup.sh [<name>]
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creates a encrypted backup of the btrfs subvolume mounted at `/`
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EOF
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exit 1
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fi
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echo "creating btrfs snapshot with name: '$name'"
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zst_name="$name.btrfs.zst"
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out_name="/backups/$zst_name.gpg"
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prompt=0
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if [[ -d /snapshots/"$name" ]]; then
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prompt=1
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echo "snapshot already exists: /snapshots/$name" >&2
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fi
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if [[ -f "$out_name" ]]; then
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prompt=1
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echo "output file already exists: $out_name" >&2
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fi
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mapfile -t existing_backups < <(find /backups/ -maxdepth 1 -name 'snap-*.btrfs.zst.gpg' -print)
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for existing_backup in "${existing_backups[@]}"; do
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if [[ "$existing_backup" != "$out_name" ]]; then
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echo "other backup files exist, you should copy them to a remote system and then delete them." >&2
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echo "If you don't delete them, they will be included in this backup, using waay more space than necessary." >&2
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printf "e.g., run: sudo rm %q\n" "$existing_backup" >&2
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exit 1
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fi
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done
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if ((prompt)); then
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if read -r -p "snapshot and/or output file already exists, do you want to overwrite them? [y/n]: " -t 300 REPLY && [[ "$REPLY" =~ ^[yY]$ ]]; then
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btrfs subvolume delete /snapshots/"$name"
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rm -f "$out_name"
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else
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echo "exiting" >&2
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exit 1
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fi
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fi
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btrfs subvolume snapshot -r / /snapshots/"$name"
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echo "encrypting and writing to: $out_name"
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exec 3<&0
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btrfs send "${clone_sources[@]}" /snapshots/"$name" | zstd --fast -T0 | gpg --symmetric --compress-algo none --set-filename "$zst_name" -o- /dev/fd/4 4<&0- <&3 > "$out_name"
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echo "written to: $out_name"
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