snapper: keep 6 hourly + 10 numbered, drop daily/weekly/monthly

Shorter retention to align with other process changes. Hourly cap
drops from 10 to 6, daily/weekly/monthly/yearly all disabled, and
NUMBER_LIMIT pinned at 10 (was the snapper default of 50) so manual
and pre-/post- snapshots have a known ceiling too.

Applies to both the root and postgres snapper configs.

Author: passcod

docs/GUIDE-IMAGES.md

@@ -117,7 +117,7 @@ Simple quotas are enabled to track per-subvolume disk usage.
 
 Transparent filesystem compression is enabled system-wide.
 
-The Snapper snapshot manager is enabled by default, which takes snapshots of the subvolumes hourly and retains them for default 10 hours / 7 days / 4 weeks / 12 months periods.
+The Snapper snapshot manager is enabled by default, which takes hourly snapshots of the subvolumes and retains the last 6 hourly snapshots, plus up to 10 numbered (manual / pre-/post-) snapshots.
 This provides a simple way to rollback a server or a file to an earlier configuration and protects against catastrophes.
 
 The system partition can be grown or shrunk while online.

docs/spec/disk-images.md

@@ -238,8 +238,9 @@ A weekly cron job must be present to run `apt install -y tailscale`.
 
 r[image.snapper.root]
 Snapper must be configured for the root subvolume (`/`) with timeline
-snapshots enabled and retention of 10 hourly, 7 daily, 4 weekly, and
-12 monthly snapshots.
+snapshots enabled and retention of 6 hourly snapshots, plus 10 numbered
+(non-timeline) snapshots. Daily, weekly, monthly, and yearly timeline
+retention must be disabled.
 
 r[image.snapper.postgres]
 Snapper must be configured for the PostgreSQL subvolume

image/scripts/setup-snapper.sh

@@ -11,10 +11,12 @@ snapper --no-dbus -c root set-config \
     TIMELINE_CREATE=yes \
     TIMELINE_CLEANUP=yes \
     NUMBER_CLEANUP=yes \
-    TIMELINE_LIMIT_HOURLY=10 \
-    TIMELINE_LIMIT_DAILY=7 \
-    TIMELINE_LIMIT_WEEKLY=4 \
-    TIMELINE_LIMIT_MONTHLY=12
+    NUMBER_LIMIT=10 \
+    TIMELINE_LIMIT_HOURLY=6 \
+    TIMELINE_LIMIT_DAILY=0 \
+    TIMELINE_LIMIT_WEEKLY=0 \
+    TIMELINE_LIMIT_MONTHLY=0 \
+    TIMELINE_LIMIT_YEARLY=0
 
 # r[image.snapper.postgres]: Configure snapper for the PostgreSQL subvolume
 mkdir -p /var/lib/postgresql
@@ -23,10 +25,12 @@ snapper --no-dbus -c postgres set-config \
     TIMELINE_CREATE=yes \
     TIMELINE_CLEANUP=yes \
     NUMBER_CLEANUP=yes \
-    TIMELINE_LIMIT_HOURLY=10 \
-    TIMELINE_LIMIT_DAILY=7 \
-    TIMELINE_LIMIT_WEEKLY=4 \
-    TIMELINE_LIMIT_MONTHLY=12
+    NUMBER_LIMIT=10 \
+    TIMELINE_LIMIT_HOURLY=6 \
+    TIMELINE_LIMIT_DAILY=0 \
+    TIMELINE_LIMIT_WEEKLY=0 \
+    TIMELINE_LIMIT_MONTHLY=0 \
+    TIMELINE_LIMIT_YEARLY=0
 
 # r[image.snapper.timers]: Enable snapper timers
 systemctl enable snapper-timeline.timer

tests/test-image-structure.sh

@@ -436,10 +436,13 @@ check "snapper root config exists" test -f "$SNAPPER_ROOT_CFG"
 if [ -f "$SNAPPER_ROOT_CFG" ]; then
     check "snapper root: TIMELINE_CREATE=yes" grep -q '^TIMELINE_CREATE="yes"' "$SNAPPER_ROOT_CFG"
     check "snapper root: TIMELINE_CLEANUP=yes" grep -q '^TIMELINE_CLEANUP="yes"' "$SNAPPER_ROOT_CFG"
-    check "snapper root: TIMELINE_LIMIT_HOURLY=10" grep -q '^TIMELINE_LIMIT_HOURLY="10"' "$SNAPPER_ROOT_CFG"
-    check "snapper root: TIMELINE_LIMIT_DAILY=7" grep -q '^TIMELINE_LIMIT_DAILY="7"' "$SNAPPER_ROOT_CFG"
-    check "snapper root: TIMELINE_LIMIT_WEEKLY=4" grep -q '^TIMELINE_LIMIT_WEEKLY="4"' "$SNAPPER_ROOT_CFG"
-    check "snapper root: TIMELINE_LIMIT_MONTHLY=12" grep -q '^TIMELINE_LIMIT_MONTHLY="12"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: NUMBER_CLEANUP=yes" grep -q '^NUMBER_CLEANUP="yes"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: NUMBER_LIMIT=10" grep -q '^NUMBER_LIMIT="10"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: TIMELINE_LIMIT_HOURLY=6" grep -q '^TIMELINE_LIMIT_HOURLY="6"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: TIMELINE_LIMIT_DAILY=0" grep -q '^TIMELINE_LIMIT_DAILY="0"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: TIMELINE_LIMIT_WEEKLY=0" grep -q '^TIMELINE_LIMIT_WEEKLY="0"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: TIMELINE_LIMIT_MONTHLY=0" grep -q '^TIMELINE_LIMIT_MONTHLY="0"' "$SNAPPER_ROOT_CFG"
+    check "snapper root: TIMELINE_LIMIT_YEARLY=0" grep -q '^TIMELINE_LIMIT_YEARLY="0"' "$SNAPPER_ROOT_CFG"
 fi
 
 # r[verify image.snapper.postgres]
@@ -448,10 +451,13 @@ check "snapper postgres config exists" test -f "$SNAPPER_PG_CFG"
 if [ -f "$SNAPPER_PG_CFG" ]; then
     check "snapper postgres: TIMELINE_CREATE=yes" grep -q '^TIMELINE_CREATE="yes"' "$SNAPPER_PG_CFG"
     check "snapper postgres: TIMELINE_CLEANUP=yes" grep -q '^TIMELINE_CLEANUP="yes"' "$SNAPPER_PG_CFG"
-    check "snapper postgres: TIMELINE_LIMIT_HOURLY=10" grep -q '^TIMELINE_LIMIT_HOURLY="10"' "$SNAPPER_PG_CFG"
-    check "snapper postgres: TIMELINE_LIMIT_DAILY=7" grep -q '^TIMELINE_LIMIT_DAILY="7"' "$SNAPPER_PG_CFG"
-    check "snapper postgres: TIMELINE_LIMIT_WEEKLY=4" grep -q '^TIMELINE_LIMIT_WEEKLY="4"' "$SNAPPER_PG_CFG"
-    check "snapper postgres: TIMELINE_LIMIT_MONTHLY=12" grep -q '^TIMELINE_LIMIT_MONTHLY="12"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: NUMBER_CLEANUP=yes" grep -q '^NUMBER_CLEANUP="yes"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: NUMBER_LIMIT=10" grep -q '^NUMBER_LIMIT="10"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: TIMELINE_LIMIT_HOURLY=6" grep -q '^TIMELINE_LIMIT_HOURLY="6"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: TIMELINE_LIMIT_DAILY=0" grep -q '^TIMELINE_LIMIT_DAILY="0"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: TIMELINE_LIMIT_WEEKLY=0" grep -q '^TIMELINE_LIMIT_WEEKLY="0"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: TIMELINE_LIMIT_MONTHLY=0" grep -q '^TIMELINE_LIMIT_MONTHLY="0"' "$SNAPPER_PG_CFG"
+    check "snapper postgres: TIMELINE_LIMIT_YEARLY=0" grep -q '^TIMELINE_LIMIT_YEARLY="0"' "$SNAPPER_PG_CFG"
 fi
 
 # ============================================================