ceph/qa/tasks/netem.py

"""
Task to run tests with network delay between two remotes using tc and netem.
Reference:https://wiki.linuxfoundation.org/networking/netem.

"""

import logging
import contextlib
from teuthology import misc as teuthology
from cStringIO import StringIO
from teuthology.orchestra import run
from teuthology import contextutil
from paramiko import SSHException
import socket
import time
import gevent
import argparse

log = logging.getLogger(__name__)


def set_priority(interface):

    # create a priority queueing discipline
    return ['sudo', 'tc', 'qdisc', 'add', 'dev', interface, 'root', 'handle', '1:', 'prio']


def show_tc(interface):

    # shows tc device present
    return ['sudo', 'tc', 'qdisc', 'show', 'dev', interface]


def del_tc(interface):

    return ['sudo', 'tc', 'qdisc', 'del', 'dev', interface, 'root']


def cmd_prefix(interface):

    # prepare command to set delay
    cmd1 = ['sudo', 'tc', 'qdisc', 'add', 'dev', interface, 'parent',
                     '1:1', 'handle', '2:', 'netem', 'delay']

    # prepare command to change delay
    cmd2 = ['sudo', 'tc', 'qdisc', 'replace', 'dev', interface, 'root', 'netem', 'delay']

    # prepare command to apply filter to the matched ip/host

    cmd3 = ['sudo', 'tc', 'filter', 'add', 'dev', interface,
                     'parent', '1:0', 'protocol', 'ip', 'pref', '55',
                     'handle', '::55', 'u32', 'match', 'ip', 'dst']

    return cmd1, cmd2, cmd3


def static_delay(remote, host, interface, delay):

    """ Sets a constant delay between two hosts to emulate network delays using tc qdisc and netem"""

    set_delay, change_delay, set_ip = cmd_prefix(interface)

    ip = socket.gethostbyname(host.hostname)

    r = remote.run(args=show_tc(interface), stdout=StringIO())
    if r.stdout.getvalue().strip().find('refcnt') == -1:
        # call set_priority() func to create priority queue
        # if not already created(indicated by -1)
        log.info('Create priority queue')
        remote.run(args=set_priority(interface))

        # set static delay, with +/- 5ms jitter with normal distribution as default
        log.info('Setting delay to %s' % delay)
        set_delay.extend(['%s' % delay, '5ms', 'distribution', 'normal'])
        remote.run(args=set_delay)

        # set delay to a particular remote node via ip
        log.info('Delay set on %s' % remote)
        set_ip.extend(['%s' % ip, 'flowid', '2:1'])
        remote.run(args=set_ip)
    else:
        # if the device is already created, only change the delay
        log.info('Setting delay to %s' % delay)
        change_delay.extend(['%s' % delay, '5ms', 'distribution', 'normal'])
        remote.run(args=change_delay)


def variable_delay(remote, host, interface, delay_range=[]):

    """ Vary delay between two values"""

    set_delay, change_delay, set_ip = cmd_prefix(interface)

    ip = socket.gethostbyname(host.hostname)

    # delay1 has to be lower than delay2
    delay1 = delay_range[0]
    delay2 = delay_range[1]

    r = remote.run(args=show_tc(interface), stdout=StringIO())
    if r.stdout.getvalue().strip().find('refcnt') == -1:
        # call set_priority() func to create priority queue
        # if not already created(indicated by -1)
        remote.run(args=set_priority(interface))

        # set variable delay
        log.info('Setting varying delay')
        set_delay.extend(['%s' % delay1, '%s' % delay2])
        remote.run(args=set_delay)

        # set delay to a particular remote node via ip
        log.info('Delay set on %s' % remote)
        set_ip.extend(['%s' % ip, 'flowid', '2:1'])
        remote.run(args=set_ip)
    else:
        # if the device is already created, only change the delay
        log.info('Setting varying delay')
        change_delay.extend(['%s' % delay1, '%s' % delay2])
        remote.run(args=change_delay)


def delete_dev(remote, interface):

    """ Delete the qdisc if present"""

    log.info('Delete tc')
    r = remote.run(args=show_tc(interface), stdout=StringIO())
    if r.stdout.getvalue().strip().find('refcnt') != -1:
        remote.run(args=del_tc(interface))


class Toggle:

    stop_event = gevent.event.Event()

    def __init__(self, ctx, remote, host, interface, interval):
        self.ctx = ctx
        self.remote = remote
        self.host = host
        self.interval = interval
        self.interface = interface
        self.ip = socket.gethostbyname(self.host.hostname)

    def packet_drop(self):

        """ Drop packets to the remote ip specified"""

        _, _, set_ip = cmd_prefix(self.interface)

        r = self.remote.run(args=show_tc(self.interface), stdout=StringIO())
        if r.stdout.getvalue().strip().find('refcnt') == -1:
            self.remote.run(args=set_priority(self.interface))
            # packet drop to specific ip
            log.info('Drop all packets to %s' % self.host)
            set_ip.extend(['%s' % self.ip, 'action', 'drop'])
            self.remote.run(args=set_ip)

    def link_toggle(self):

        """
         For toggling packet drop and recovery in regular interval.
         If interval is 5s, link is up for 5s and link is down for 5s
        """

        while not self.stop_event.is_set():
            self.stop_event.wait(timeout=self.interval)
            # simulate link down
            try:
                self.packet_drop()
                log.info('link down')
            except SSHException as e:
                log.debug('Failed to run command')

            self.stop_event.wait(timeout=self.interval)
            # if qdisc exist,delete it.
            try:
                delete_dev(self.remote, self.interface)
                log.info('link up')
            except SSHException as e:
                log.debug('Failed to run command')

    def begin(self, gname):
        self.thread = gevent.spawn(self.link_toggle)
        self.ctx.netem.names[gname] = self.thread

    def end(self, gname):
        self.stop_event.set()
        log.info('gname is {}'.format(self.ctx.netem.names[gname]))
        self.ctx.netem.names[gname].get()

    def cleanup(self):
        """
        Invoked during unwinding if the test fails or exits before executing task 'link_recover'
        """
        log.info('Clean up')
        self.stop_event.set()
        self.thread.get()


@contextlib.contextmanager
def task(ctx, config):

    """
    - netem:
          clients: [c1.rgw.0]
          iface: eno1
          dst_client: [c2.rgw.1]
          delay: 10ms

    - netem:
          clients: [c1.rgw.0]
          iface: eno1
          dst_client: [c2.rgw.1]
          delay_range: [10ms, 20ms] # (min, max)

    - netem:
          clients: [rgw.1, mon.0]
          iface: eno1
          gname: t1
          dst_client: [c2.rgw.1]
          link_toggle_interval: 10 # no unit mentioned. By default takes seconds.

    - netem:
          clients: [rgw.1, mon.0]
          iface: eno1
          link_recover: [t1, t2]


    """

    log.info('config %s' % config)

    assert isinstance(config, dict), \
        "please list clients to run on"
    if not hasattr(ctx, 'netem'):
        ctx.netem = argparse.Namespace()
        ctx.netem.names = {}

    if config.get('dst_client') is not None:
        dst = config.get('dst_client')
        (host,) = ctx.cluster.only(dst).remotes.iterkeys()

    for role in config.get('clients', None):
        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
        ctx.netem.remote = remote
        if config.get('delay', False):
            static_delay(remote, host, config.get('iface'), config.get('delay'))
        if config.get('delay_range', False):
            variable_delay(remote, host, config.get('iface'), config.get('delay_range'))
        if config.get('link_toggle_interval', False):
            log.info('Toggling link for %s' % config.get('link_toggle_interval'))
            global toggle
            toggle = Toggle(ctx, remote, host, config.get('iface'), config.get('link_toggle_interval'))
            toggle.begin(config.get('gname'))
        if config.get('link_recover', False):
            log.info('Recovering link')
            for gname in config.get('link_recover'):
                toggle.end(gname)
                log.info('sleeping')
                time.sleep(config.get('link_toggle_interval'))
                delete_dev(ctx.netem.remote, config.get('iface'))
                del ctx.netem.names[gname]

    try:
        yield
    finally:
        if ctx.netem.names:
            toggle.cleanup()
        for role in config.get('clients'):
            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
            delete_dev(remote, config.get('iface'))