From 70145d5897e29a3efbf39eb24e25f77c7b6a260b Mon Sep 17 00:00:00 2001
From: hygienic-books <hygienic-books@tentic.net>
Date: Mon, 6 Mar 2023 02:47:11 +0100
Subject: [PATCH] feat(script): Add dry-run functionality (#1)

---
 pacman-zfs-snapshot.sh | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/pacman-zfs-snapshot.sh b/pacman-zfs-snapshot.sh
index 49be235..cbf5c06 100755
--- a/pacman-zfs-snapshot.sh
+++ b/pacman-zfs-snapshot.sh
@@ -194,12 +194,16 @@ function do_snaps () {
     local snap_name
     for snappable_dataset in "${snappable_datasets[@]}"; do
         snap_name="${snappable_dataset}"'@'"${snap_name_prefix}${snap_field_separator}${date_string}${snap_field_separator}"'op:'"${operation}${snap_field_separator}"'sev:'"${severity}${snap_field_separator}"'pkgs:'"${trimmed_pkg_list_oneline}"
-        zfs snapshot "${snap_name}" && {
-            successfully_snapped_datasets+=("${snappable_dataset}")
-            pprint 'info' 'Snapshot done: '"${snap_name}"
-        } || {
-            pprint 'warn' 'Snapshot failed: '"${snap_name}"
-        }
+        if [[ "${do_dry_run}" == 'true' ]]; then
+            pprint 'info' 'Dry-run, pretending to run zfs snapshot '"${snap_name}"
+        else
+            zfs snapshot "${snap_name}" && {
+                successfully_snapped_datasets+=("${snappable_dataset}")
+                pprint 'info' 'Snapshot done: '"${snap_name}"
+            } || {
+                pprint 'warn' 'Snapshot failed: '"${snap_name}"
+            }
+        fi
     done
 }
 
@@ -214,18 +218,22 @@ function get_snaps_in_cur_sev () {
 
 function do_retention () {
     local snap_list snaps_done_by_us snaps_in_cur_sev snaps_limit oldest_snap
-    for successfully_snapped_dataset in "${successfully_snapped_datasets[@]}"; do        
-        snaps_in_cur_sev="$(get_snaps_in_cur_sev "${successfully_snapped_dataset}")"
-        if [[ "${severity}" == "${snaps_important_suffix}" ]]; then
-            snaps_limit="${snaps_important_keep}"
-        else
-            snaps_limit="${snaps_trivial_keep}"
-        fi
-        while [[ "$(get_snaps_in_cur_sev "${successfully_snapped_dataset}" | wc -l)" -gt "${snaps_limit}" ]]; do
-            oldest_snap="$(get_snaps_in_cur_sev "${successfully_snapped_dataset}" | head -n1)"
-            zfs destroy "${oldest_snap}"
+    if [[ "${do_dry_run}" == 'true' ]]; then
+        pprint 'info' 'Dry-run, skipping potential zfs destroy operations ...'
+    else
+        for successfully_snapped_dataset in "${successfully_snapped_datasets[@]}"; do        
+            snaps_in_cur_sev="$(get_snaps_in_cur_sev "${successfully_snapped_dataset}")"
+            if [[ "${severity}" == "${snaps_important_suffix}" ]]; then
+                snaps_limit="${snaps_important_keep}"
+            else
+                snaps_limit="${snaps_trivial_keep}"
+            fi
+            while [[ "$(get_snaps_in_cur_sev "${successfully_snapped_dataset}" | wc -l)" -gt "${snaps_limit}" ]]; do
+                oldest_snap="$(get_snaps_in_cur_sev "${successfully_snapped_dataset}" | head -n1)"
+                zfs destroy "${oldest_snap}"
+            done
         done
-    done
+    fi
 }
 
 function main () {