debian: migrate legacy mac/ipam cache/state files

We opted for a simple copy of the legacy file to the new location,
since any other migration path would be too strenuous. The worst-case
scenario of failures with this approach is losing IPAM / MAC entries
that are created during the update window in the legacy files by nodes
that are not yet updated to the new version. Those can be fixed by a
simple start / stop of the affected VMs, triggering a rewrite of the
IPAM database.

Signed-off-by: Stefan Hanreich <s.hanreich@proxmox.com>
 [ TL: output message if files get moved and add todo-comment ]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

debian/libpve-network-perl.postinst

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+set -e
+
+migrate_ipam_db() {
+  LEGACY_IPAM_DB_FILE="/etc/pve/priv/ipam.db"
+  IPAM_DB_FILE="/etc/pve/sdn/pve-ipam-state.json"
+
+  if test -f "$LEGACY_IPAM_DB_FILE" && test ! -f "$IPAM_DB_FILE"; then
+    echo "copying over existing legacy IPAM state file to new path..."
+    cp $LEGACY_IPAM_DB_FILE $IPAM_DB_FILE
+  fi
+}
+
+migrate_mac_cache() {
+  LEGACY_MAC_DB_FILE="/etc/pve/priv/macs.db"
+  MAC_DB_FILE="/etc/pve/sdn/mac-cache.json"
+
+  if test -f "$LEGACY_MAC_DB_FILE" && test ! -f "$MAC_DB_FILE"; then
+    echo "copying over existing legacy IPAM MAC-map cache file to new path..."
+    cp $LEGACY_MAC_DB_FILE $MAC_DB_FILE
+  fi
+}
+
+case "$1" in
+  configure)
+    # TODO: remove with PVE 9+
+    if dpkg --compare-versions "$2" 'lt' '0.9.9'; then
+      migrate_ipam_db
+      migrate_mac_cache
+    fi
+  ;;
+esac
+
+exit 0