This is a quick-and-dirty tool to reformat XML configuration files to make it possible to diff them. It only preserves tag and attribute values.

xmlsort.py

#!/usr/bin/python

from xml.etree import ElementTree as ET
import sys

def compareString(a,b):
    aLower = a.lower()
    bLower = b.lower()
    order = 0
    if aLower > bLower:
        order = 1
    elif aLower < bLower:
        order = -1
    return order

def compareAttr(attr, a, b):
    order = 0
    if attr in a.attrib and attr in b.attrib:
        #print ("comparing",a.attrib[attr],b.attrib[attr])
        order = compareString(a.attrib[attr], b.attrib[attr])
    return order

def compareNodes(a,b):
    order = compareString(a.tag, b.tag)
    if order == 0:
        order = compareAttr("key", a, b)
    return order

def sortedChildren(root):
    children = []
    for child in root:
        children.append(child)
    return sorted(children, cmp=compareNodes)

def printSorted(node, indent=0):
    sys.stdout.write('  ' * indent)
    sys.stdout.write('<'+node.tag)
    if len(node.attrib) > 2:
        for key,value in sorted(node.attrib.iteritems()):
            sys.stdout.write("\n")
            sys.stdout.write('  ' * (1+indent))
            sys.stdout.write(key+'="'+value+'"')
        sys.stdout.write("\n")
        sys.stdout.write('  ' * indent)
    else:
        for key,value in node.attrib.iteritems():
            sys.stdout.write(' '+key+'="'+value+'"')
    if len(node) > 0:
        sys.stdout.write('>')
        sys.stdout.write("\n")
        for child in sortedChildren(node):
            printSorted(child, indent+1)
        sys.stdout.write('  ' * indent)
        sys.stdout.write('</'+node.tag+'>')
    else:
        sys.stdout.write(' />')
    sys.stdout.write("\n")

if len(sys.argv) != 2:
    exit -1
else:
    fileName = sys.argv[1]

xml = ET.parse(fileName)
root = xml.getroot()

printSorted(root, 0)