ceph-volume: configuration: create a module to load/parse ceph configs

Signed-off-by: Alfredo Deza <adeza@redhat.com>

diff --git a/src/ceph-volume/ceph_volume/configuration.py b/src/ceph-volume/ceph_volume/configuration.py
new file mode 100644 (file)
index 0000000..69e893a
--- /dev/null
+++ b/src/ceph-volume/ceph_volume/configuration.py
@@ -0,0 +1,82 @@
+try:
+    import configparser
+except ImportError:
+    import ConfigParser as configparser
+import logging
+import os
+import re
+from ceph_volume import terminal
+from ceph_volume import exceptions
+
+
+logger = logging.getLogger(__name__)
+
+
+class _TrimIndentFile(object):
+    """
+    This is used to take a file-like object and removes any
+    leading tabs from each line when it's read. This is important
+    because some ceph configuration files include tabs which break
+    ConfigParser.
+    """
+    def __init__(self, fp):
+        self.fp = fp
+
+    def readline(self):
+        line = self.fp.readline()
+        return line.lstrip(' \t')
+
+    def __iter__(self):
+        return iter(self.readline, '')
+
+
+def load(abspath=None):
+    parser = Conf()
+    try:
+        if abspath and os.path.exists(abspath):
+            parser.read(abspath)
+        else:
+            raise exceptions.ConfigurationError(abspath=abspath)
+        return parser
+    except configparser.ParsingError as error:
+        terminal.error('Unable to read configuration file: %s' % abspath)
+        terminal.error(str(error))
+        logger.exception('Unable to parse INI-style file: %s' % abspath)
+
+
+class Conf(configparser.SafeConfigParser):
+    """
+    Subclasses from SafeConfigParser to give a few helpers for Ceph
+    configuration.
+    """
+
+    def get_safe(self, section, key, default=None):
+        """
+        Attempt to get a configuration value from a certain section
+        in a ``cfg`` object but returning None if not found. Avoids the need
+        to be doing try/except {ConfigParser Exceptions} every time.
+        """
+        try:
+            return self.get(section, key)
+        except (configparser.NoSectionError, configparser.NoOptionError):
+            return default
+
+    def get_list(self, section, key):
+        """
+        Assumes that the value for a given key is going to be a list separated
+        by commas. It gets rid of trailing comments.  If just one item is
+        present it returns a list with a single item, if no key is found an
+        empty list is returned.
+        """
+        value = self.get_safe(section, key, [])
+        if value == []:
+            return value
+
+        # strip comments
+        value = re.split(r'\s+#', value)[0]
+
+        # split on commas
+        value = value.split(',')
+
+        # strip spaces
+        return [x.strip() for x in value]