support configuration of landscape-client via cloud-config (LP: #857366)

This adds the ability to configure landscape client code from
cloud-config.  The fields available are those that were populated to
/etc/landscape/client.conf when I ran landscape-config on precise
('11.07.1.1-0ubuntu2')

cloudinit/CloudConfig/cc_landscape.py

@@ -0,0 +1,67 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2011 Canonical Ltd.
+#
+#    Author: Scott Moser <scott.moser@canonical.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 cloudinit.CloudConfig import per_instance
+from configobj import ConfigObj
+
+frequency = per_instance
+
+lsc_client_cfg_file = "/etc/landscape/client.conf"
+
+# defaults taken from stock client.conf in landscape-client 11.07.1.1-0ubuntu2
+lsc_builtincfg = { 
+  'client': {
+    'log_level': "info",
+    'url': "https://landscape.canonical.com/message-system",
+    'ping_url': "http://landscape.canonical.com/ping",
+    'data_path': "/var/lib/landscape/client",
+  }
+}
+
+def handle(name,cfg,cloud,log,args):
+    """
+    Basically turn a top level 'landscape' entry with a 'client' dict
+    and render it to ConfigObj format under '[client]' section in
+    /etc/landscape/client.conf
+    """
+
+    ls_cloudcfg = cfg.get("landscape", { })
+
+    if not isinstance(ls_cloudcfg, dict):
+        raise(Exception("'landscape' existed in config, but not a dict"))
+
+    merged = mergeTogether([lsc_builtincfg, lsc_client_cfg_file, ls_cloudcfg])
+
+    with open(lsc_client_cfg_file, "w") as fp:
+        merged.write(fp)
+
+    log.debug("updated %s" % lsc_client_cfg_file)
+
+def mergeTogether(objs):
+    """
+    merge together ConfigObj objects or things that ConfigObj() will take in
+    later entries override earlier
+    """
+    if len(objs) == 0:
+        return { }
+    cfg = ConfigObj(objs[1])
+    for obj in objs[1:]:
+        if isinstance(obj, ConfigObj):
+            cfg.merge(obj)
+        else:
+            cfg.merge(ConfigObj(obj))
+    return cfg

config/cloud.cfg

@@ -19,6 +19,7 @@ cloud_config_modules:
  - set-passwords
  - grub-dpkg
  - apt-update-upgrade
+ - landscape
  - timezone
  - puppet
  - chef

doc/examples/cloud-config-landscape.txt

@@ -0,0 +1,13 @@
+# Landscape-client configuration
+#
+# Anything under the top 'landscape: client' entry
+# will be basically rendered into a ConfigObj formated file
+# under the '[client]' section of /etc/landscape/client.conf
+# 
+landscape:
+  client:
+    url: "https://landscape.canonical.com/message-system"
+    ping_url: "http://landscape.canonical.com/ping"
+    data_path: "/var/lib/landscape/client"
+    http_proxy: "http://my.proxy.com/foobar"
+    tags: [ server, cloud ]