Use a set of helper/parsing classes to perform system configuration

Previously file modification of system configuration was done
in a functional and hard to test manner. Now instead this patch
allows for a manner that provides a nice object oriented
interface to those objects as well as makes it possible to test
those parsing entities without having to invoke distro class code.
   - Created parsers for:
    - /etc/sysconfig
    - /etc/hostname
    - resolv.conf
    - /etc/hosts

Moved duplicated functionality into the root level distro class including:
 - apply_hostname
 - set_hostname
 - *various shared configuration file names/paths*

1 files changed, 20 insertions, 5 deletions

diff --git a/cloudinit/util.py b/cloudinit/util.py
index 4f5b15ee..ab918433 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -52,6 +52,7 @@ from cloudinit import importer
 from cloudinit import log as logging
 from cloudinit import safeyaml
 from cloudinit import url_helper as uhelp
+from cloudinit import version
 
 from cloudinit.settings import (CFG_BUILTIN)
 
@@ -272,11 +273,7 @@ def uniq_merge(*lists):
             # Kickout the empty ones
             a_list = [a for a in a_list if len(a)]
         combined_list.extend(a_list)
-    uniq_list = []
-    for i in combined_list:
-        if i not in uniq_list:
-            uniq_list.append(i)
-    return uniq_list
+    return uniq_list(combined_list)
 
 
 def clean_filename(fn):
@@ -989,6 +986,16 @@ def peek_file(fname, max_bytes):
         return ifh.read(max_bytes)
 
 
+def uniq_list(in_list):
+    out_list = []
+    for i in in_list:
+        if i in out_list:
+            continue
+        else:
+            out_list.append(i)
+    return out_list
+
+
 def load_file(fname, read_cb=None, quiet=False):
     LOG.debug("Reading from %s (quiet=%s)", fname, quiet)
     ofh = StringIO()
@@ -1428,6 +1435,14 @@ def subp(args, data=None, rcs=None, env=None, capture=True, shell=False,
     return (out, err)
 
 
+def make_header(comment_char="#", base='created'):
+    ci_ver = version.version_string()
+    header = str(comment_char)
+    header += " %s by cloud-init v. %s" % (base.title(), ci_ver)
+    header += " on %s" % time_rfc2822()
+    return header
+
+
 def abs_join(*paths):
     return os.path.abspath(os.path.join(*paths))