kvm_net

#!/usr/bin/env python3
"""

=head1 NAME

kvm_net - Munin plugin to show the network I/O per VM


=head1 APPLICABLE SYSTEMS

Virtualization server with VMs based on KVM may be able to track the network
traffic of their VMs, if the KVM processes are started in a specific way.

Probably proxmox-based virtualization hosts fit into this category.

You can easily check if your KVM processes are started in the expected way, by
running the following command:

  ps -ef | grep "netdev.*ifname="

The plugin can be used, if the above command outputs one line for every
currently running VM.

In all other cases you need to use other munin plugins instead, e.g. "libvirt".


=head1 CONFIGURATION

parsed environment variables:

  * vmsuffix: part of vm name to be removed


=head1 AUTHOR

Copyright (C) 2012 - Igor Borodikhin
Copyright (C) 2018 - Lars Kruse <devel@sumpfralle.de>


=head1 LICENSE

GPLv3


=head1 MAGIC MARKERS

 #%# capabilities=autoconf
 #%# family=contrib

=cut
"""

import os
import re
from subprocess import Popen, PIPE
import sys


VM_NAME_REGEX = re.compile("^.*\x00-{arg_name}\x00(.+)\x00.*$")
KVM_INTERFACE_NAME_REGEX = re.compile("(?:^|,)ifname=([^,]+)(?:,|$)")


def config(vm_names):
    """ Print the plugin's config

    @param vm_names : a list of "cleaned" vms' name
    """
    print("graph_title KVM Network I/O")
    print("graph_vlabel Bytes rx(-)/tx(+) per second")
    print("graph_category virtualization")
    print("graph_args --base 1024")
    print("graph_info This graph shows the network I/O of the virtual "
          "machines. It is only usable for VMs that were started in a very "
          "specific way. If you see no values in the diagrams, then you "
          "should check, if the command \"ps -ef | grep 'netdev.*ifname='\" "
          "returns one line of output for every running VM. If there is no "
          "output, then you need to change the setup of your VMs or you need "
          "to use a different munin plugin for monitoring the network traffic "
          "(e.g. 'libvirt').")
    print()
    for vm in vm_names:
        print("%s_in.label %s" % (vm, vm))
        print("%s_in.type COUNTER" % vm)
        print("%s_in.min 0" % vm)
        print("%s_in.graph no" % vm)
        print("%s_out.negative %s_in" % (vm, vm))
        print("%s_out.label %s" % (vm, vm))
        print("%s_out.type COUNTER" % vm)
        print("%s_out.min 0" % vm)


def clean_vm_name(vm_name):
    """ Replace all special chars

    @param vm_name : a vm's name
    @return cleaned vm's name
    """
    # suffix part defined in conf
    suffix = os.getenv("vmsuffix")
    if suffix:
        vm_name = re.sub(suffix, "", vm_name)
    # proxmox uses kvm with -name parameter
    parts = vm_name.split('\x00')
    if (parts[0].endswith('kvm')):
        try:
            return parts[parts.index('-name')+1]
        except ValueError:
            pass
    return re.sub(r"[^a-zA-Z0-9_]", "_", vm_name)


def fetch(vms):
    """ Fetch values for a list of pids

    @param dictionary {kvm_pid: cleaned vm name}
    """
    for pid, vm_data in vms.items():
        vm_interface_names = get_vm_network_interface_names(pid)
        sum_incoming = 0
        sum_outgoing = 0
        interface_found = False
        with open("/proc/net/dev", "r") as net_file:
            for line in net_file.readlines():
                tokens = line.split()
                current_interface_name = tokens[0].rstrip(":").strip()
                if current_interface_name in vm_interface_names:
                    sum_incoming += int(tokens[1])
                    sum_outgoing += int(tokens[9])
                    interface_found = True
            if not interface_found:
                # we want to distinguish "no traffic" from "not found"
                sum_incoming = "U"
                sum_outgoing = "U"
            print("%s_in.value %s" % (vm_data, sum_incoming))
            print("%s_out.value %s" % (vm_data, sum_outgoing))


def get_vm_network_interface_names(pid):
    """ return the MAC addresses configured for network interfacs of a PID """
    result = set()
    for netdev_description in _get_kvm_process_arguments(pid, "netdev"):
        match = KVM_INTERFACE_NAME_REGEX.search(netdev_description)
        if match:
            result.add(match.groups()[0])
    return result


def detect_kvm():
    """ Check if kvm is installed """
    kvm = Popen(["which", "kvm"], stdout=PIPE)
    kvm.communicate()
    return kvm.returncode == 0


def find_vm_names(pids):
    """Find and clean vm names from pids

    @return a dictionary of {pids : cleaned vm name}
    """
    result = {}
    for pid in pids:
        name = None
        name_arg_values = _get_kvm_process_arguments(pid, "name")
        if name_arg_values:
            name_arg_value = name_arg_values[0]
            if "," in name_arg_value:
                # the modern parameter format may look like this:
                #    guest=foo,debug-threads=on
                for index, token in enumerate(name_arg_value.split(",")):
                    if (index == 0) and ("=" not in token):
                        # the first item may the plain name
                        name = value
                    elif "=" in token:
                        key, value = token.split("=", 1)
                        if key == "guest":
                            name = value
                    else:
                        # unknown format (no "mapping")
                        pass
            else:
                name = name_arg_value
        if name is None:
            print("Failed to parse VM name from commandline of process: {}"
                  .format(name_arg_values), file=sys.stderr)
        else:
            result[pid] = clean_vm_name(name)
    return result


def _get_kvm_process_arguments(pid, arg_name):
    """ parse all value with the given name from the process identified by PID

    The result is a list of tokens, that follow this argument name. The result
    is empty in case of problems.
    """
    # the "cmdline" (e.g. /proc/self/cmdline) is a null-separated token list
    try:
        with open("/proc/%s/cmdline" % pid, "r") as cmdline_file:
            cmdline = cmdline_file.read()
    except IOError:
        # the process seems to have died meanwhile
        return []
    is_value = False
    result = []
    for arg_token in cmdline.split("\0"):
        if is_value:
            # the previous token was our argument name
            result.append(arg_token)
            is_value = False
        elif arg_token == "-{}".format(arg_name):
            # this is our argument name - we want to store the next value
            is_value = True
        else:
            # any other irrelevant value
            pass
    return result


def list_pids():
    """ Find the pid of kvm processes

    @return a list of pids from running kvm
    """
    pid = Popen(["pidof", "qemu-kvm", "qemu-system-x86_64", "kvm"], stdout=PIPE)
    return pid.communicate()[0].decode().split()


if __name__ == "__main__":
    action = sys.argv[1] if len(sys.argv) > 1 else None
    if action == "autoconf":
        if detect_kvm():
            print("yes")
        else:
            print("no")
    elif action == "config":
        vm_data = find_vm_names(list_pids())
        config(vm_data.values())
    else:
        vm_data = find_vm_names(list_pids())
        fetch(vm_data)