System config niceness!

1. Move out the old helpers that provided oop access/reading/writing
   to various standard conf files and place those in parsers instead.
2. Unify the 'update_hostname' which varied very little	between	distros
   and make it generic so that subclasses can only provide a couple of 
   functions to	obtain the hostname updating functionality
3. Implement that new set of functions in rhel/debian    
4. Use the new parsers chop_comment function for similar use 
   cases as well as add a new utils make header	function that
   can be used for configuration files that are	newly generated
   to use (less	duplication here of this same thing being done
   in multiple places.
5. Add in a distro '_apply_hostname' which calls out to	the 'hostname'
   program to set the system hostname (more duplication	elimination).
6. Make the 'constant' filenames being written to for configuration
   by the various distros be instance members instead of string
   constants 'sprinkled' throughout the code

1 files changed, 171 insertions, 0 deletions

diff --git a/cloudinit/distros/parsers/resolv_conf.py b/cloudinit/distros/parsers/resolv_conf.py
new file mode 100644
index 00000000..377ada6b
--- /dev/null
+++ b/cloudinit/distros/parsers/resolv_conf.py
@@ -0,0 +1,171 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from StringIO import StringIO
+
+from cloudinit import util
+
+from cloudinit.distros.parsers import chop_comment
+
+
+# See: man resolv.conf
+class ResolvConf(object):
+    def __init__(self, text):
+        self._text = text
+        self._contents = None
+
+    def parse(self):
+        if self._contents is None:
+            self._contents = self._parse(self._text)
+
+    @property
+    def nameservers(self):
+        self.parse()
+        return self._retr_option('nameserver')
+
+    @property
+    def local_domain(self):
+        self.parse()
+        dm = self._retr_option('domain')
+        if dm:
+            return dm[0]
+        return None
+
+    @property
+    def search_domains(self):
+        self.parse()
+        current_sds = self._retr_option('search')
+        flat_sds = []
+        for sdlist in current_sds:
+            for sd in sdlist.split(None):
+                if sd:
+                    flat_sds.append(sd)
+        return flat_sds
+
+    def __str__(self):
+        self.parse()
+        contents = StringIO()
+        for (line_type, components) in self._contents:
+            if line_type == 'blank':
+                contents.write("\n")
+            elif line_type == 'all_comment':
+                contents.write("%s\n" % (components[0]))
+            elif line_type == 'option':
+                (cfg_opt, cfg_value, comment_tail) = components
+                line = "%s %s" % (cfg_opt, cfg_value)
+                if len(comment_tail):
+                    line += comment_tail
+                contents.write("%s\n" % (line))
+        return contents.getvalue()
+
+    def _retr_option(self, opt_name):
+        found = []
+        for (line_type, components) in self._contents:
+            if line_type == 'option':
+                (cfg_opt, cfg_value, _comment_tail) = components
+                if cfg_opt == opt_name:
+                    found.append(cfg_value)
+        return found
+
+    def add_nameserver(self, ns):
+        self.parse()
+        current_ns = self._retr_option('nameserver')
+        new_ns = list(current_ns)
+        new_ns.append(str(ns))
+        new_ns = util.uniq_list(new_ns)
+        if len(new_ns) == len(current_ns):
+            return current_ns
+        if len(current_ns) >= 3:
+            # Hard restriction on only 3 name servers
+            raise ValueError(("Adding %r would go beyond the "
+                              "'3' maximum name servers") % (ns))
+        self._remove_option('nameserver')
+        for n in new_ns:
+            self._contents.append(('option', ['nameserver', n, '']))
+        return new_ns
+
+    def _remove_option(self, opt_name):
+
+        def remove_opt(item):
+            line_type, components = item
+            if line_type != 'option':
+                return False
+            (cfg_opt, _cfg_value, _comment_tail) = components
+            if cfg_opt != opt_name:
+                return False
+            return True
+
+        new_contents = []
+        for c in self._contents:
+            if not remove_opt(c):
+                new_contents.append(c)
+        self._contents = new_contents
+
+    def add_search_domain(self, search_domain):
+        flat_sds = self.search_domains
+        new_sds = list(flat_sds)
+        new_sds.append(str(search_domain))
+        new_sds = util.uniq_list(new_sds)
+        if len(flat_sds) == len(new_sds):
+            return new_sds
+        if len(flat_sds) >= 6:
+            # Hard restriction on only 6 search domains
+            raise ValueError(("Adding %r would go beyond the "
+                              "'6' maximum search domains") % (search_domain))
+        s_list  = " ".join(new_sds)
+        if len(s_list) > 256:
+            # Some hard limit on 256 chars total
+            raise ValueError(("Adding %r would go beyond the "
+                              "256 maximum search list character limit")
+                              % (search_domain))
+        self._remove_option('search')
+        self._contents.append(('option', ['search', s_list, '']))
+        return flat_sds
+
+    @local_domain.setter
+    def local_domain(self, domain):
+        self.parse()
+        self._remove_option('domain')
+        self._contents.append(('option', ['domain', str(domain), '']))
+        return domain
+
+    def _parse(self, contents):
+        entries = []
+        for (i, line) in enumerate(contents.splitlines()):
+            sline = line.strip()
+            if not sline:
+                entries.append(('blank', [line]))
+                continue
+            (head, tail) = chop_comment(line, ';#')
+            if not len(head.strip()):
+                entries.append(('all_comment', [line]))
+                continue
+            if not tail:
+                tail = ''
+            try:
+                (cfg_opt, cfg_values) = head.split(None, 1)
+            except (IndexError, ValueError):
+                raise IOError("Incorrectly formatted resolv.conf line %s"
+                              % (i + 1))
+            if cfg_opt not in ['nameserver', 'domain',
+                               'search', 'sortlist', 'options']:
+                raise IOError("Unexpected resolv.conf option %s" % (cfg_opt))
+            entries.append(("option", [cfg_opt, cfg_values, tail]))
+        return entries
+
+