Split configuration file handling into its own module

rbackup/config.py

@@ -0,0 +1,108 @@
+"""
+.. :author:: Eric Torres
+.. :module:: rbackup.config
+.. :synopsis: Functions for handling config files.
+"""
+import configparser
+import logging
+import re
+from contextlib import contextmanager
+from pathlib import Path
+from tempfile import NamedTemporaryFile
+
+# ========== Logging Setup ===========
+syslog = logging.getLogger(__name__)
+
+# ========== Constants ==========
+COMMENT_REGEX = r"^[^#; ]+"
+
+# ----- Paths -----
+CONFIG_DIR = Path("/etc/rbackup")
+MAIN_CONFIG_FILE = CONFIG_DIR / "backup.conf"
+
+# ----- Exit Codes -----
+E_NO_CONFIG_FILE = 4
+
+
+# ========== Functions ==========
+def get_files_by_suffix(suffix):
+    """Retrieve all include files from the program configuration directory.
+
+    >>> get_files_by_suffix('-include.conf') # doctest: +ELLIPSIS
+    ...
+
+    :param suffix: the suffix to search for
+    :type suffix: str
+    :returns: paths pointing to include files
+    :rtype: generator of path-like objects
+    """
+    yield from CONFIG_DIR.glob(f"*{suffix}")
+
+
+def merge_files(files):
+    """Parse, filter, and sort through config files to create a single
+    --files-from argument.
+
+        Any files included that do not exist send a warning to the log.
+
+    >>> merge_files() # doctest: +ELLIPSIS
+    PosixPath(/tmp/...)
+
+    :param files: files including paths to read from
+    :type files: iterable of path-like objects
+    :returns: path to file that lists include paths
+    :rtype: path-like object
+    """
+    include_lines = []
+
+    for file in files:
+        with file.open(mode="r") as opened_file:
+            include_lines.extend(
+                l for l in opened_file.readlines() if re.match(COMMENT_REGEX, l)
+            )
+
+    include_lines.sort()
+
+    with NamedTemporaryFile(mode="w", delete=False) as include_paths:
+        include_paths.writelines(include_lines)
+
+    return Path(include_paths.name)
+
+
+@contextmanager
+def merge_include_files():
+    """Merge include file paths into one file and yield its path for use with rsync.
+
+    :return: path-like object
+    """
+    filelist = merge_files(get_files_by_suffix("-include.conf"))
+    yield filelist
+    filelist.unlink()
+
+
+@contextmanager
+def merge_exclude_files():
+    """Merge exclude file paths into one file and yield its path for use with rsync.
+
+    :return: path-like object
+    """
+    filelist = merge_files(get_files_by_suffix("-exclude.conf"))
+    yield filelist
+    filelist.unlink()
+
+
+def parse_configfile():
+    """Parse a config file given its path and return
+    a ConfigParser object.
+
+    :returns: object used to parse config file
+    :rtype: ConfigParser object
+    :raises: FileNotFoundError if path does not exist
+    """
+    if not MAIN_CONFIG_FILE.is_file():
+        raise FileNotFoundError(f"{MAIN_CONFIG_FILE} does not exist")
+
+    config_reader = configparser.ConfigParser()
+    config_reader.read(MAIN_CONFIG_FILE)
+
+    return config_reader