add get_hostname_fqdn method to 'util' and use it for getting hostname

This adds a method 'get_hostname_fqdn' to cloudinit.util, and then
uses this method for getting the hostname and fqdn in places that get 
hostname.

The single place for getting it right will help.

4 files changed, 26 insertions, 4 deletions

diff --git a/cloudinit/CloudConfig/cc_set_hostname.py b/cloudinit/CloudConfig/cc_set_hostname.py
index 2b130810..b505b621 100644
--- a/cloudinit/CloudConfig/cc_set_hostname.py
+++ b/cloudinit/CloudConfig/cc_set_hostname.py
@@ -23,8 +23,8 @@ def handle(name,cfg,cloud,log,args):
         log.debug("preserve_hostname is set. not setting hostname")
         return(True)
 
+    ( hostname, fqdn ) = util.get_hostname_fqdn(cfg, cloud)
     try:
-        hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
         set_hostname(hostname, log)
     except Exception as e:
         util.logexc(log)
diff --git a/cloudinit/CloudConfig/cc_update_etc_hosts.py b/cloudinit/CloudConfig/cc_update_etc_hosts.py
index d33eaa25..fe4489ad 100644
--- a/cloudinit/CloudConfig/cc_update_etc_hosts.py
+++ b/cloudinit/CloudConfig/cc_update_etc_hosts.py
@@ -22,8 +22,7 @@ import StringIO
 frequency = per_always
 
 def handle(name,cfg,cloud,log,args):
-    hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
-    fqdn = util.get_cfg_option_str(cfg,"fqdn",cloud.get_hostname(fqdn=True))
+    ( hostname, fqdn ) = util.get_hostname_fqdn(cfg, cloud)
 
     if util.get_cfg_option_bool(cfg,"manage_etc_hosts", True):
         # manage_etc_hosts not true, update the 127.0.1.1 entry via update_etc_hosts
diff --git a/cloudinit/CloudConfig/cc_update_hostname.py b/cloudinit/CloudConfig/cc_update_hostname.py
index 9ef02251..3f55c73b 100644
--- a/cloudinit/CloudConfig/cc_update_hostname.py
+++ b/cloudinit/CloudConfig/cc_update_hostname.py
@@ -27,8 +27,8 @@ def handle(name,cfg,cloud,log,args):
         log.debug("preserve_hostname is set. not updating hostname")
         return
 
+    ( hostname, fqdn ) = util.get_hostname_fqdn(cfg, cloud)
     try:
-        hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
         prev ="%s/%s" % (cloud.get_cpath('data'),"previous-hostname")
         update_hostname(hostname, prev, log)
     except Exception as e:
diff --git a/cloudinit/util.py b/cloudinit/util.py
index b3842afa..64eafa29 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -422,3 +422,26 @@ def islxc():
             raise
 
     return False
+
+def get_hostname_fqdn(cfg, cloud):
+    # return the hostname and fqdn from 'cfg'.  If not found in cfg,
+    # then fall back to data from cloud
+    if "fqdn" in cfg:
+        # user specified a fqdn.  Default hostname then is based off that
+        fqdn = cfg['fqdn']
+        hostname = get_cfg_option_str(cfg,"hostname",fqdn.split('.')[0])
+    else:
+        if "hostname" in cfg and cfg['hostname'].find('.') > 0:
+            # user specified hostname, and it had '.' in it
+            # be nice to them.  set fqdn and hostname from that
+            fqdn = cfg['hostname']
+            hostname = cfg['hostname'][:fqdn.find('.')]
+        else
+            # no fqdn set, get fqdn from cloud. 
+            # get hostname from cfg if available otherwise cloud
+            fqdn = cloud.get_hostname(fqdn=True)
+            if "hostname" in cfg:
+                hostname = cfg['hostname']
+            else:
+                hostname = cloud.get_hostname()
+    return(hostname, fqdn)