Detect and enable swap partitions on live

The laptops owned by SOI have 8 GB of RAM, and live systems running on
them sometimes run out of memory. To mitigate this, find and enable the
swap partition of the installed OS on the internal SSD.

os/layers/live/includes.chroot/etc/systemd/system/detect-swap.service

@@ -0,0 +1,14 @@
+[Unit]
+Description=detect and enable swap partitions.
+Before=basic.target
+After=local-fs.target systemd-tmpfiles-setup.service
+DefaultDependencies=no
+ConditionKernelCommandLine=boot=live
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+ExecStart=/usr/local/bin/detect-swap
+
+[Install]
+WantedBy=basic.target

os/layers/live/includes.chroot/usr/local/bin/detect-swap

@@ -0,0 +1,13 @@
+#!/usr/bin/python3
+
+import subprocess
+import json
+
+SD_GPT_SWAP = '0657fd6d-a4ab-43c4-84e5-0933c84b4f4f'
+
+lsblk_result = subprocess.run(['lsblk', '--json', '--output=PATH,PARTTYPE'], check=True, stdout=subprocess.PIPE)
+lablk_out = json.loads(lsblk_result.stdout)
+for block in lablk_out['blockdevices']:
+    if block['parttype'] == SD_GPT_SWAP:
+        print('Enabling swap on', block['path'])
+        subprocess.run(['swapon', block['path']])