Add support for ssh keys in cloud-config. move write_file to util.

----
#cloud-config
apt_update: true
ssh_keys:
  rsa_private: |
    -----BEGIN RSA PRIVATE KEY-----
    MIIBxwIBAAJhAKD0YSHy73nUgysO13XsJmd4fHiFyQ+00R7VVu2iV9Qcon2LZS/x
    ...
    REPPOyrAspdeOAV+6VKRavstea7+2DZmSUgE
    -----END RSA PRIVATE KEY-----

  rsa_public: ssh-rsa AAAAB3NzaC1yc2E...18QJvWPocKJtlsDNi3 smoser@host

  dsa_private: |
    -----BEGIN DSA PRIVATE KEY-----
    MIIBuwIBAAKBgQDP2HLu7pTExL89USyM0264RCyWX/CMLmukxX0Jdbm29ax8FBJT
    ...
    8KucvUYbOEI+yv+5LW9u3z/BAoGBAI0q6JP+JvJmwZFaeCMMVxXUbqiSko/P1lsa
    -----END DSA PRIVATE KEY-----

  dsa_public: ssh-dss AAAAB3NzaC1kc3M...ybngIy66PMEoQ= smoser@host
----

3 files changed, 30 insertions, 20 deletions

diff --git a/ec2init/CloudConfig.py b/ec2init/CloudConfig.py
index 17a14363..d6947ce1 100644
--- a/ec2init/CloudConfig.py
+++ b/ec2init/CloudConfig.py
@@ -158,11 +158,18 @@ class CloudConfig():
             try: os.unlink(f)
             except: pass
 
-        if False:
+        if self.cfg.has_key("ssh_keys"):
             # if there are keys in cloud-config, use them
-            # TODO: need to get keys from cloud-config if present
-            # and replace those in /etc/ssh
-            pass
+            key2file = {
+                "rsa_private" : ("/etc/ssh/ssh_host_rsa_key", 0600),
+                "rsa_public"  : ("/etc/ssh/ssh_host_rsa_key.pub", 0644),
+                "dsa_private" : ("/etc/ssh/ssh_host_dsa_key", 0600),
+                "dsa_public"  : ("/etc/ssh/ssh_host_dsa_key.pub", 0644)
+            }
+
+            for key,val in self.cfg["ssh_keys"].items():
+                if key2file.has_key(key):
+                    util.write_file(key2file[key][0],val,key2file[key][1])
         else:
             # if not, generate them
             genkeys ='ssh-keygen -f /etc/ssh/ssh_host_rsa_key -t rsa -N ""; '
diff --git a/ec2init/__init__.py b/ec2init/__init__.py
index 80203c80..cfd54e8d 100644
--- a/ec2init/__init__.py
+++ b/ec2init/__init__.py
@@ -143,8 +143,8 @@ class EC2Init:
         self.store_userdata()
 
     def store_userdata(self):
-        write_file(userdata_raw, self.datasource.get_userdata_raw(), 0644)
-        write_file(userdata, self.datasource.get_userdata(), 0644)
+        util.write_file(userdata_raw, self.datasource.get_userdata_raw(), 0644)
+        util.write_file(userdata, self.datasource.get_userdata(), 0644)
 
     def initctl_emit(self):
         subprocess.Popen(['initctl', 'emit', 'cloud-config',
@@ -240,14 +240,14 @@ class EC2Init:
             return
 
         filename=filename.replace(os.sep,'_')
-        write_file("%s/%s" % (user_scripts_dir,filename), payload, 0700)
+        util.write_file("%s/%s" % (user_scripts_dir,filename), payload, 0700)
 
     def handle_upstart_job(self,data,ctype,filename,payload):
         if ctype == "__end__" or ctype == "__begin__": return
         if not filename.endswith(".conf"):
             filename=filename+".conf"
 
-        write_file("%s/%s" % ("/etc/init",filename), payload, 0644)
+        util.write_file("%s/%s" % ("/etc/init",filename), payload, 0644)
 
     def handle_cloud_config(self,data,ctype,filename,payload):
         if ctype == "__begin__":
@@ -313,15 +313,3 @@ class EC2Init:
 
         subprocess.Popen(['swapon', '-a']).communicate()
 
-def write_file(file,content,mode=0644):
-        try:
-            os.makedirs(os.path.dirname(file))
-        except OSError as e:
-            if e.errno != errno.EEXIST:
-                raise e
-
-        f=open(file,"wb")
-        f.write(content)
-        f.close()
-        os.chmod(file,mode)
-
diff --git a/ec2init/util.py b/ec2init/util.py
index c1da0e71..0737f117 100644
--- a/ec2init/util.py
+++ b/ec2init/util.py
@@ -1,4 +1,6 @@
 import yaml
+import os
+import errno
 
 def read_conf(fname):
 	stream = file(fname)
@@ -27,3 +29,16 @@ def mergedict(src,cand):
             else:
                 src[k] = mergedict(src[k],v)
     return src
+
+def write_file(file,content,mode=0644):
+        try:
+            os.makedirs(os.path.dirname(file))
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise e
+
+        f=open(file,"wb")
+        f.write(content)
+        f.close()
+        os.chmod(file,mode)
+