with Drive() structure

src/main.py

@@ -1,6 +1,7 @@
 from datetime import datetime
 import subprocess
 import requests
+import sys
 import os
 
 import config
@@ -9,9 +10,19 @@ def log(*args, **kwargs):
     date = datetime.now().strftime('%d-%b-%Y %H:%M:%S')
     print(f"[{date}]", *args, **kwargs)
 
+def log_error(*args, **kwargs):
+    date = datetime.now().strftime('%d-%b-%Y %H:%M:%S')
+    print(f"[{date}]", *args, **kwargs, file=sys.stderr)
+
+def check_return_code(ret, *args, **kwargs):
+    if ret != 0:
+        log_error(*args, **kwargs)
+        exit(1)
+
 
 if not os.path.exists(config.DISK):
     log_error(f"Drive {config.DISK} not present on the system")
+    exit(1)
 
 passwd = requests.get(config.PWD_URL).text.strip()
 log("Got password :", passwd)
@@ -20,16 +31,36 @@ ssh_key_passwd = requests.get(config.SSH_KEY_PWD_URL).text.strip()
 log("Got password :", ssh_key_passwd)
 
 
+class Drive():
+    def __init__(self, disk, passwd, mount_location):
+        self.disk = disk
+        self.passwd = passwd
+        self.mount_location = mount_location
+
+    def __enter__(self):
         subprocess.run([
             "cryptsetup", "luksOpen",
-    config.DISK, "backup"
+            self.disk, "backup"
-], input=passwd, text=True)
+        ], input=self.passwd, text=True)
 
         subprocess.call([
             "mount", "/dev/mapper/backup",
-    config.MNT_LOCATION
+            self.mount_location
+        ])
+        return self
+
+    def __exit__(self, exception_type, exception_value, exception_traceback):
+        subprocess.call([
+            "umount", self.mount_location
         ])
 
+        subprocess.call([
+            "cryptsetup", "luksClose",
+            "/dev/mapper/backup"
+        ])
+
+
+with Drive(config.DISK, passwd, config.MNT_LOCATION) as backup_drive:
     log("Successfully mounted, doing the backup stuff")
 
     os.makedirs(
@@ -39,7 +70,7 @@ os.makedirs(
 
     for src, dest in config.BACKUP_MAP:
         # We could also use a rsync daemon on the remote machine for pwd(-less) auth
-    subprocess.call(
+        ret = subprocess.call(
             [
                 "sshpass", "-P", "passphrase", "-e",
                     "rsync",
@@ -52,15 +83,17 @@ for src, dest in config.BACKUP_MAP:
             ],
             env={**os.environ, "SSHPASS":ssh_key_passwd}
         )
+        check_return_code(ret, f"Error when syncing {config.REMOTE_LOCATION}")
 
     log("Rsync ok. Creating snapshot.")
 
-subprocess.call([
+    ret = subprocess.call([
         "cp", "-a",
         "--reflink=always", #! The partition must be Btrfs or XFS
         os.path.join(config.MNT_LOCATION, "latest"),
         os.path.join(config.MNT_LOCATION, datetime.today().strftime('%Y-%m-%d'))
     ])
+    check_return_code(ret, f"Error when creating snapshot")
 
     log("Snapshot ok. Deleting unneeded backups.")
 
@@ -68,13 +101,7 @@ log("Snapshot ok. Deleting unneeded backups.")
 
     log("Unmounting.")
 
-subprocess.call([
+log("Everything okay, done !")
-    "umount", config.MNT_LOCATION
-])
 
-subprocess.call([
+with open("latest-success", "w") as f:
-    "cryptsetup", "luksClose",
+    f.write(datetime.today().strftime('%Y-%m-%d'))
-    "/dev/mapper/backup"
-])
-
-log("Done !")