From 342a619d15b8b0fb8afef8eb41f1abf891a5778f Mon Sep 17 00:00:00 2001
From: Tibo De Peuter <tibo.depeuter@gmail.com>
Date: Sat, 30 Dec 2023 17:44:37 +0100
Subject: [PATCH] Improve backup script

---
 scripts/backup-zfs-dataset.sh | 49 ++++++++++++++++-------------------
 1 file changed, 22 insertions(+), 27 deletions(-)

diff --git a/scripts/backup-zfs-dataset.sh b/scripts/backup-zfs-dataset.sh
index db9fbd3..54eaa57 100755
--- a/scripts/backup-zfs-dataset.sh
+++ b/scripts/backup-zfs-dataset.sh
@@ -2,6 +2,9 @@
 # Create archived backups of zfs datasets
 # Usage: backup-zfs-dataset [OPTIONS] [<dataset> <destination>]
 
+# This script makes use of SFTP and authenticates using the .netrc file in the users home directory.
+# You should configure your system accordingly.
+
 usage() {
     >&2 printf "Usage: %s [OPTIONS] [<dataset> <destination>]\n" "$0"
     >&2 printf "Options:\n"
@@ -28,22 +31,18 @@ while [[ $# -gt 0 ]]; do
             shift 2
             ;;
         -d | --destination)
-            if ! [ -d "${2}" ]; then
-                >&2 printf "Error: Specified destination does not exist: '%s'\n" "${2}"
-                usage
-            fi
             destination="${2}"
             shift 2
             ;;
 	-b | --base)
-	    if [ "${create_base:=1}" -neq 1 ]; then
+	    if [ "${create_base:=1}" -ne 1 ]; then
                 >&2 printf "Error: Cannot create base backup when specifying differently.\n"
 		usage
 	    fi
 	    shift 1
 	    ;;
         -i | --incremental)
-	    if [ "${create_base:=0}" -neq 0 ]; then
+	    if [ "${create_base:=0}" -ne 0 ]; then
 	        >&2 printf "Error: Cannot create incremental backup when specifying differently.\n"
 		usage
             fi
@@ -84,9 +83,6 @@ if [[ -z "${dataset:=${1}}" || -z "${destination:=${2}}" ]]; then
 elif [ -z "${dataset}" ]; then
     >&2 printf "Error: Invalid dataset: '%s'\n" "${1}"
     usage
-elif ! [ -d "${destination}" ]; then
-    >&2 printf "Error: Specified destination does not exist: '%s'\n" "${2}"
-    usage
 fi
 
 # Set defaults
@@ -99,12 +95,13 @@ if [ "${create_base:=0}" -eq 1 ]; then
     output_filename="${destination}/${tag:=}${snapshot_name}.gz"
     # Create ZFS snapshot
     printf "Creating snapshot\n"
-    sudo zfs snapshot "${dataset}@${snapshot_name}"
+    sudo zfs snapshot -r "${dataset}@${snapshot_name}"
     # Compress it
     printf "Backing up now\n"
-    sudo zfs send --verbose "${dataset}@${snapshot_name}" \
+    sudo zfs send --verbose -R "${dataset}@${snapshot_name}" \
         | gzip "-${compression_level}" --verbose --rsyncable \
-        | split - --verbose -b "${max_size}" "${output_filename}.part."
+        | split - --verbose -b "${max_size}" \
+            --filter "curl --netrc -kaT - sftp://${output_filename}"
     printf "Written base backup to: '%s'.\n" "${output_filename}"
     printf "Done!\n"
     exit 0
@@ -113,21 +110,18 @@ fi
 # Working snapshots
 
 # Find snapshots
-snapshot_location="/mnt/${dataset}/.zfs/snapshot"
-latest_auto="$( find "${snapshot_location}"/* -maxdepth 0 -name 'auto*' -type d | sort -n | tail -n1 | xargs -n1 basename )"
-latest_manual="$( find "${snapshot_location}"/* -maxdepth 0 -name 'manual*' -type d | sort -n | tail -n1 | xargs -n1 basename )"
+snapshots="$( find "/mnt/${dataset}/.zfs/snapshot"/* -maxdepth 0 -name 'auto*' -type d | sed -E 's/.*-([0-9]{4}-[0-9]{2}-[0-9]{2}_[0-9]{2}-[0-9]{2})/\1\t&/' | sort -n | cut -f 2- | xargs -n1 basename )"
+# Use the two latest snapshots
+from_snapshot="$( tail -n2 <<< "${snapshots}" | head -n1 )"
+to_snapshot="$( tail -n2 <<< "${snapshots}" | tail -n1 )"
 
 # Check snapshots existance
-if ! [ -n "${latest_manual}" ]; then
-    >&2 printf "Error: No manual snapshot could be found!\n"
+if [ -z "${from_snapshot}" ] || [ -z "${to_snapshot}" ]; then
+    >&2 printf "Error: Less than two snapshots could be found:\n"
+    >&2 printf "       From: '%s'\n" "${from_snapshot}"
+    >&2 printf "       To:   '%s'\n" "${to_snapshot}"
     exit 2
 fi
-if ! [ -n "${latest_auto}" ]; then
-    >&2 printf "Error: No automatic snapshot could be found!\n"
-    exit 2
-fi
-
-printf "Latest manual snapshot: %s\nLatest auto snapshot: %s\n" "${latest_manual}" "${latest_auto}"
 
 # Abort entire script if anything fails.
 set -e
@@ -135,11 +129,12 @@ set -e
 # Backups
 
 # Incremental incremental backup.
-printf "Creating incremental backup between %s and %s\n" "${latest_manual}" "${latest_auto}"
-output_filename="${destination}/${tag}${latest_manual}-${latest_auto}.gz"
-sudo zfs send --verbose -i "@${latest_manual}" "${dataset}@${latest_auto}" \
+printf "Creating incremental backup between '%s' and '%s'\n" "${from_snapshot}" "${to_snapshot}"
+output_filename="${destination}/${tag}${from_snapshot}-${to_snapshot}.gz"
+sudo zfs send --verbose -R -i "@${from_snapshot}" "${dataset}@${to_snapshot}" \
     | gzip "-${compression_level}" --verbose \
-    | split - --verbose -b "${max_size}" "${output_filename}.part."
+    | split - --verbose -b "${max_size}" \
+        --filter "curl --netrc -kaT - sftp://${output_filename}"
 printf "Written incremental backup to: %s\n" "${output_filename}"
 
 # TODO Cleanup