Split main backup script into separate library modules

bin/backup

@@ -23,15 +23,12 @@ import argparse
 import logging
 import os
 import sys
-from contextlib import contextmanager
-from subprocess import CalledProcessError
 
 import rbackup.config.config_files as config
-import rbackup.rsync
+import rbackup.script as script
 from rbackup.struct.repository import Repository
 
 # ========== Constants ==========
-SCRIPT_UMASK = 0000
 LOGFORMAT = "==> %(levelname)s %(message)s"
 EXTRA_RSYNC_OPTS = {
     "dry_run": "--dry-run",
@@ -40,11 +37,10 @@ EXTRA_RSYNC_OPTS = {
     "update": "--update",
 }
 
-
 # ----- Error Codes -----
-E_INVALID_SNAPSHOT_NAME = 2
 E_PERMISSION = 13
 
+
 # ========== Logging Setup ==========
 console_formatter = logging.Formatter(LOGFORMAT)
 syslog = logging.getLogger("rbackup")
@@ -111,47 +107,18 @@ def parse_cmdline_arguments(**kwargs):
     return parser.parse_args(**kwargs)
 
 
-@contextmanager
-def change_umask(override=None):
-    """Creates a context manager in which the umask is changed.
-    This is to ensure that the script's desired umask is not
-    visible to the user.
-
-    :param override: non-script-default umask value to use
-    :type override: int
-    """
-    try:
-        if override is not None:
-            old_umask = os.umask(override)
-        else:
-            old_umask = os.umask(SCRIPT_UMASK)
-        yield
-    finally:
-        os.umask(old_umask)
-
-
 # ========== Main Script ==========
 if __name__ == "__main__":
     args = parse_cmdline_arguments()
-    parsed_config = config.parse_configfile()
-
-    repo = None
 
     try:
+        parsed_config = config.parse_configfile()
         repo = Repository(args.repository)
     except PermissionError as e:
         syslog.critical(e)
         exit(E_PERMISSION)
-
-    rsync_opts = config.load_list_from_option(
-        parsed_config,
-        section="main",
-        option="RsyncOptions",
-        fallback=rbackup.rsync.DEFAULT_RSYNC_OPTS.copy(),
-    )
-
-    if args.extra_rsync_opts is not None:
-        rsync_opts.extend(args.extra_rsync_opts)
+    else:
+        script.do_backup(repo, parsed_config, args)
 
     if args.verbose:
         stdout_handler.setLevel(logging.INFO)
@@ -159,32 +126,6 @@ if __name__ == "__main__":
     if args.debug:
         stdout_handler.setLevel(logging.DEBUG)
 
-    # We want to iterate through the repository and create the --link-dest
-    # options before creating the new snapshot
-    link_dests = tuple(f"--link-dest={s.path}" for s in repo)
-
-    curr_snapshot = None
-
-    with change_umask(args.umask), config.merge_include_files() as include_file, config.merge_exclude_files() as exclude_file:
-        try:
-            curr_snapshot = repo.create_snapshot(args.name)
-            rbackup.rsync.rsync(
-                *rsync_opts,
-                f"--files-from={include_file}",
-                f"--exclude-from={exclude_file}",
-                *link_dests,
-                "/",
-                str(curr_snapshot),
-            )
-        except ValueError as e:
-            syslog.critical(e)
-            exit(E_INVALID_SNAPSHOT_NAME)
-        except CalledProcessError as e:
-            syslog.critical("Backup process failed")
-            syslog.critical(f"Failing command: {e.cmd}")
-            syslog.critical(e.stderr)
-            exit(e.returncode)
-
     if args.run_post_sync:
         syslog.info("Running sync operation")
         os.sync()

rbackup/script.py

@@ -0,0 +1,71 @@
+"""
+.. moduleauthor:: Eric Torres
+.. module:: rbackup.script
+    :synopsis: library for common script operations
+"""
+
+import logging
+from subprocess import CalledProcessError
+
+import rbackup.config.config_files as config
+import rbackup.rsync
+import rbackup.system as system
+
+# ========== Constants ==========
+# ----- Error Codes -----
+E_INVALID_SNAPSHOT_NAME = 2
+E_PERMISSION = 13
+
+
+# ========== Logging Setup ===========
+syslog = logging.getLogger(__name__)
+
+
+# ========== Functions ==========
+def do_backup(repository, parsed_config, args):
+    """Run a backup operation.
+
+    It is up to the caller to decide on how to instantiate the Repository object.
+
+    :param repository: repository to operate on
+    :type repository: ``rbackup.struct.repository.Repository`` object
+    :param parsed_config:
+    :type parsed_config: ``configparser.ConfigParser`` object
+    :param args: arguments relevant to the backup operation
+    :type args: ``argparse.Namespace`` object
+    """
+    rsync_opts = config.load_list_from_option(
+        parsed_config,
+        section="main",
+        option="RsyncOptions",
+        fallback=rbackup.rsync.DEFAULT_RSYNC_OPTS.copy(),
+    )
+
+    if args.extra_rsync_opts is not None:
+        rsync_opts.extend(args.extra_rsync_opts)
+
+    # We want to iterate through the repository and create the --link-dest
+    # options before creating the new snapshot
+    link_dests = tuple(f"--link-dest={s.path}" for s in repository)
+
+    with system.change_umask(
+        args.umask
+    ), config.merge_include_files() as include_file, config.merge_exclude_files() as exclude_file:
+        try:
+            curr_snapshot = repository.create_snapshot(args.name)
+            rbackup.rsync.rsync(
+                *rsync_opts,
+                f"--files-from={include_file}",
+                f"--exclude-from={exclude_file}",
+                *link_dests,
+                "/",
+                str(curr_snapshot),
+            )
+        except ValueError as e:
+            syslog.critical(e)
+            exit(E_INVALID_SNAPSHOT_NAME)
+        except CalledProcessError as e:
+            syslog.critical("Backup process failed")
+            syslog.critical(f"Failing command: {e.cmd}")
+            syslog.critical(e.stderr)
+            exit(e.returncode)

rbackup/system.py

@@ -0,0 +1,36 @@
+"""
+.. moduleauthor:: Eric Torres
+.. module:: rbackup.system
+    :synopsis: library for interacting with rbackup over the network
+"""
+
+import logging
+import os
+from contextlib import contextmanager
+
+# ========== Constants ==========
+DEFAULT_UMASK = 0000
+
+
+# ========== Logging Setup ===========
+syslog = logging.getLogger(__name__)
+
+
+# ========== Functions ==========
+@contextmanager
+def change_umask(override=None):
+    """Creates a context manager in which the umask is changed.
+    This is to ensure that the script's desired umask is not
+    visible to the user.
+
+    :param override: non-script-default umask value to use
+    :type override: int
+    """
+    try:
+        if override is not None:
+            old_umask = os.umask(override)
+        else:
+            old_umask = os.umask(DEFAULT_UMASK)
+        yield
+    finally:
+        os.umask(old_umask)