UBUNTU: SAUCE: hv: hv_set_ifconfig -- convert to python3

From 15.10 onwards python2 is no longer the default python and is no longer
installed by default.  Switch to python3 which is.  This delta is much
larger than the nominal changes as inconsistent spacing is now an error.
I have also corrected the use of loose strings as comments.

BugLink: http://bugs.launchpad.net/bugs/1506521Signed-off-by: Andy Whitcroft <apw@canonical.com>

debian/cloud-tools/hv_set_ifconfig

-#! /usr/bin/env python
+#!/usr/bin/python3
+#
+# hv_set_ifconfig <config> -- take the hv_kvp_daemon generated configuration
+#                             file and apply it to the Ubuntu configuration.
+#
+
+# CONFIG example:
+# HWADDR=11:22:33:44:55:66
+# DEVICE=foo1
+# DHCP=yes
+
+# CONFIG example:
+# HWADDR=11:22:33:44:55:66
+# DEVICE=foo1
+# IPADDR=192.168.99.10
+# GATEWAY=192.168.99.1
+# DNS1=192.168.88.250
+# IPADDR2=192.168.99.11
+# IPV6ADDR=2001:DB8:99::10
+# IPV6NETMASK=64
+# IPV6_DEFAULTGW=2001:DB8:99::10
 
 # set interfaces in hv_kvp_daemon style
 import fileinput
@@ -11,10 +31,11 @@ import subprocess
 
 if_filename="/etc/network/interfaces"
 
-'''Get quiet'''
+# Drop our output (XXX?)
 sys.stdout = open(os.devnull, 'w')
 sys.stderr = open(os.devnull, 'w')
 
+# Confirm we can open the network configuration.
 try:
 	if_file=open(if_filename,"r+")
 except IOError as e:
@@ -22,21 +43,26 @@ except IOError as e:
 else:
 	if_file.close()
 
-
-def kvp_dict(file):
-	return dict(line.strip().split("=") for line in file)
-
-
-#setting the hwaddress to something azure is not expecting is fatal networking 
-
+# Usage: hv_set_ifconfig <config>
 if len(sys.argv) != 2 :
 	exit(errno.EINVAL)
 
+#
+# Here is the format of the ip configuration file:
+#
+# HWADDR=macaddr
+# DEVICE=interface name
+# BOOTPROTO=<protocol> (where <protocol> is "dhcp" if DHCP is configured
+#                       or "none" if no boot-time protocol should be used)
+#
 kvp=dict(line.strip().split("=") for line in fileinput.input())
 
+# Setting the hwaddress to something azure is not expecting is fatal
+# to networking.
 if not "HWADDR" in kvp :
 	exit(errno.EPROTO)
 
+# Confirm we have a device specified.
 if not "DEVICE" in kvp :
 	exit(1)
 
@@ -48,10 +74,10 @@ if "DHCP" in kvp and kvp["DHCP"]=="yes" :
 	output += ["iface " + basename  + " inet dhcp"]
 	output += [""]
 else:
-	''' Matchup the interface specific lines '''
+	# Matchup the interface specific lines
 
-	'''DNS entries will go with the first interface
-	and there can be a max of three'''
+	# DNS entries will go with the first interface
+	# and there can be a max of three
 	autolist=[]
 	dns=[]
 	if "DNS1" in kvp :
@@ -62,27 +88,14 @@ else:
 				dns+=[kvp["DNS3"]]
 
 
-	'''
-	    No real max for the number of interface + aliases ... 
-	    only required is the address (but mate everything up that comes in. '''
-
-	'''ipv4 first'''
+	# No real max for the number of interface + aliases ... 
+	# only required is the address (but mate everything up that comes in.
 
+	# IPv4
 	v4names=[name for name in kvp.keys() if name.startswith("IPADDR")]
 	v4names.sort()
 
-	v6names=[name for name in kvp.keys() if name.startswith("IPV6ADDR")]
-	v6names.sort()
-
-	'''IPV6 requires a netmask'''
-	'''If an ipv6 exists, you'll want to turn off /proc/sys/net/ipv6/conf/all/autoconf with
-	up echo 0 > /proc/sys/net/ipv6/conf/all/autoconf'''
-
-	'''Counter needs to increment as soon as any interface is set.'''
-
-
 	if_count=0
-
 	for v4 in v4names:
 		ifname=basename
 		suffix=""
@@ -102,6 +115,13 @@ else:
 		output += [""]
 		if_count+=1
 
+
+	# IPv6 requires a netmask
+	# If an ipv6 exists, you'll want to turn off /proc/sys/net/ipv6/conf/all/autoconf with
+	# echo 0 > /proc/sys/net/ipv6/conf/all/autoconf
+	v6names=[name for name in kvp.keys() if name.startswith("IPV6ADDR")]
+	v6names.sort()
+
 	if6_count=0
 	if6_used=0
 	for v6 in v6names:
@@ -126,10 +146,12 @@ else:
 			if6_used += 1
 		if6_count += 1
 
+	# Mark this new interface for automatic up.
 	output = ["auto "+" ".join(autolist)] + output
-print "==================================="
-print output
-print "==================================="
+
+print("===================================")
+print(output)
+print("===================================")
 
 
 ''' Time to clean out the existing interface file'''
@@ -176,16 +198,16 @@ for line in flines:
 				pitchstanza=1
 		if not pitchstanza:
 			stanza+=[line.strip()]
-        elif line.strip() in (start_mark, end_mark):
+	elif line.strip() in (start_mark, end_mark):
 		if inastanza:
 			if not pitchstanza:
 				newfile.extend(stanza)
 			stanza=[]
-                inastanza = 0
-                pitchstanza = 0
-                # Deduplicate markers.
-                if line != prev_line:
-                    newfile += [line.strip()]
+		inastanza = 0
+		pitchstanza = 0
+		# Deduplicate markers.
+		if line != prev_line:
+		    newfile += [line.strip()]
 	else:
 		if inastanza:
 			if not pitchstanza:
@@ -193,50 +215,49 @@ for line in flines:
 		else:
 			if not pitchstanza:
 				newfile += [line.strip()]
-        prev_line=line
+	prev_line=line
 
 
 
 def emit(line):
-        print(line)
-	os.write(fd, line + "\n")
+	print(line)
+	output = line + "\n"
+	os.write(fd, output.encode('utf-8'))
 
 # Insert the new output at the end and inside the existing markers if found.
 emitted = False
 fd, path = tempfile.mkstemp()
 for line in newfile:
-        if line == end_mark:
-                emit("\n".join(output))
-                emitted = True
-        emit(line)
+	if line == end_mark:
+		emit("\n".join(output))
+		emitted = True
+	emit(line)
 if not emitted:
-        emit(start_mark)
-        emit("\n".join(output))
-        emit(end_mark)
+	emit(start_mark)
+	emit("\n".join(output))
+	emit(end_mark)
 os.close(fd)
 
 shutil.copy(path,if_filename)
-os.chmod(if_filename,0644)
-#print "TMPFILE is at: " + path
-#print "Copied file is at: " + if_filename
+os.chmod(if_filename,0o644)
 
+#print("TMPFILE is at: " + path)
+#print("Copied file is at: " + if_filename)
 
 try:
     retcode = subprocess.call("ifdown "+basename , shell=True)
     if retcode < 0:
-        print >>sys.stderr, "Child was terminated by signal", -retcode
+        print("Child was terminated by signal", -retcode, file=sys.stderr)
     else:
-        print >>sys.stderr, "Child returned", retcode
+        print("Child returned", retcode, file=sys.stderr)
 except OSError as e:
-    print >>sys.stderr, "Execution failed:", e
+    print("Execution failed:", e, file=sys.stderr)
 
 try:
     retcode = subprocess.call("ifup "+basename , shell=True)
     if retcode < 0:
-        print >>sys.stderr, "Child was terminated by signal", -retcode
+        print("Child was terminated by signal", -retcode, file=sys.stderr)
     else:
-        print >>sys.stderr, "Child returned", retcode
+        print("Child returned", retcode, file=sys.stderr)
 except OSError as e:
-    print >>sys.stderr, "Execution failed:", e
-
-
+    print("Execution failed:", e, file=sys.stderr)