#!/usr/bin/python
# vim: set fileencoding=utf-8 :
#
# Munin plugin to show the I/O load of libvirt managed virtual machines
# 
# Copyright 2008 Guido Guenther <agx@sigxcpu.org>
#
# Licesnse: GPLv2
#
# depends: python-libvirt, python-libxml2
#
#%# capabilities=autoconf
#%# family=contrib

import re, sys, os
import libvirt
import libxml2

def canon(name):
    return re.sub(r"[^a-zA-Z0-9_]", "_", name)

def print_config(uri):
    """print the plugin config, determine the domains"""

    print """graph_title Virtual Domain Block Device I/O
graph_vlabel Bytes read (-)/ written (+) per ${graph_period}
graph_category Virtual Machines
graph_info This graph shows the block device I/O of the virtual machines"""

    conn = libvirt.openReadOnly(uri)
    ids = conn.listDomainsID()
    for id in ids:
        try:
            dom = conn.lookupByID(id)
            name = dom.name()
        except libvirt.libvirtError, err:
            print >>sys.stderr, "Id: %s: %s" % (id, err)
            continue
        if name == "Domain-0":
            continue
        print "%s_read.label %s" % (canon(name), name)
        print "%s_read.type DERIVE" % canon(name)
        print "%s_read.min 0" % canon(name)
        print "%s_read.graph no" % canon(name)
        print "%s_read.draw LINE1" % canon(name)
        print "%s_write.label %s" % (canon(name), name)
        print "%s_write.type DERIVE" % canon(name)
        print "%s_write.min 0" % canon(name)
        print "%s_write.negative %s_read" % (canon(name), canon(name))
        print "%s_write.draw LINE1" % canon(name)

def get_disks(dom):
    xml = dom.XMLDesc(0)
    doc = None
    try:
        doc = libxml2.parseDoc(xml)
    except:
        return []
    ctx = doc.xpathNewContext()
    disks = []
    try:
        ret = ctx.xpathEval("/domain/devices/disk")
        for node in ret:
            devdst = None
            for child in node.children:
                if child.name == "target":
                    devdst = child.prop("dev")
            if devdst == None:
                continue
            disks.append(devdst)
    finally:
        if ctx != None:
            ctx.xpathFreeContext()
        if doc != None:
            doc.freeDoc()
    return disks
        
def fetch_values(uri):
    conn = libvirt.openReadOnly(uri)
    ids = conn.listDomainsID()
    for id in ids:
        rd = 0
        wr = 0
        try:
            dom = conn.lookupByID(id)
            name = dom.name()
        except libvirt.libvirtError, err:
            print >>sys.stderr, "Id: %s: %s" % (id, err)
            continue
        if name == "Domain-0":
            continue
        disks = get_disks(dom)
        for disk in disks:
            try:
                rd_req, rd_bytes, wr_req, wr_bytes, errs = dom.blockStats(disk)

                rd += rd_bytes
                wr += wr_bytes
            except TypeError:
                print >>sys.stderr, "Cannot get blockstats for '%s' on '%s'" % (disk, name)
        print "%s_read.value %d" % (canon(name), rd)
        print "%s_write.value %d" % (canon(name), wr)


def main(sys):
    uri = os.getenv("uri", "qemu:///system")

    if len(sys) > 1:
        if sys[1] in [ 'autoconf', 'detect' ]:
            if libvirt.openReadOnly(uri):
                print "yes"
                return 0
            else:
                print "no"
                return 1
        elif sys[1] == 'config':
            print_config(uri)
            return 0
    fetch_values(uri)
    return 0

if __name__ == "__main__":
    sys.exit(main(sys.argv))

# vim:et:ts=4:sw=4: