def single_node_test(ctx, config):
    """
    - ceph-deploy.single_node_test: null

    #rhbuild testing
    - ceph-deploy.single_node_test:
        rhbuild: 1.2.3

    """
    log.info("Testing ceph-deploy on single node")
    if config is None:
        config = {}
    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('ceph-deploy', {}))

    if config.get('rhbuild'):
        log.info("RH Build, Skip Download")
        with contextutil.nested(
            lambda: cli_test(ctx=ctx, config=config),
        ):
            yield
    else:
        with contextutil.nested(
            lambda: install_fn.ship_utilities(ctx=ctx, config=None),
            lambda: download_ceph_deploy(ctx=ctx, config=config),
            lambda: cli_test(ctx=ctx, config=config),
        ):
            yield

def upgrade_common(ctx, config, deploy_style):
    """
    Common code for upgrading
    """

    assert config is None or isinstance(config, dict), \
        "install.upgrade only supports a dictionary for configuration"

    for i in config.keys():
            assert config.get(i) is None or isinstance(
                config.get(i), dict), 'host supports dictionary'

    project = config.get('project', 'ceph')

    # use 'install' overrides here, in case the upgrade target is left
    # unspecified/implicit.
    install_overrides = ctx.config.get(
        'overrides', {}).get('install', {}).get(project, {})
    log.info('project %s config %s overrides %s', project, config, install_overrides)

    # FIXME: extra_pkgs is not distro-agnostic
    extra_pkgs = config.get('extra_packages', [])
    log.info('extra packages: {packages}'.format(packages=extra_pkgs))

    # build a normalized remote -> config dict
    remotes = {}
    if 'all' in config:
        for remote in ctx.cluster.remotes.iterkeys():
            remotes[remote] = config.get('all')
    else:
        for role in config.keys():
            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
            if remote in remotes:
                log.warn('remote %s came up twice (role %s)', remote, role)
                continue
            remotes[remote] = config.get(role)

    for remote, node in remotes.iteritems():
        if not node:
            node = {}

        this_overrides = copy.deepcopy(install_overrides)
        if 'sha1' in node or 'tag' in node or 'branch' in node:
            log.info('config contains sha1|tag|branch, removing those keys from override')
            this_overrides.pop('sha1', None)
            this_overrides.pop('tag', None)
            this_overrides.pop('branch', None)
        teuthology.deep_merge(node, this_overrides)
        log.info('remote %s config %s', remote, node)

        system_type = teuthology.get_system_type(remote)
        assert system_type in ('deb', 'rpm')
        pkgs = PACKAGES[project][system_type]
        log.info("Upgrading {proj} {system_type} packages: {pkgs}".format(
            proj=project, system_type=system_type, pkgs=', '.join(pkgs)))
            # FIXME: again, make extra_pkgs distro-agnostic
        pkgs += extra_pkgs
        node['project'] = project
        
        deploy_style(ctx, node, remote, pkgs, system_type)

def task(ctx, config):
    """
    Set up and tear down a Ceph cluster.

    For example::

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                stable: bobtail
             mon_initial_members: 1

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                dev: master
             conf:
                mon:
                   debug mon = 20

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                testing:
    """
    if config is None:
        config = {}

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('ceph-deploy', {}))

    assert isinstance(config, dict), \
        "task ceph-deploy only supports a dictionary for configuration"

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('ceph-deploy', {}))

    if config.get('branch') is not None:
        assert isinstance(config['branch'], dict), 'branch must be a dictionary'

    with contextutil.nested(
         lambda: ceph_fn.ship_utilities(ctx=ctx, config=None),
         lambda: download_ceph_deploy(ctx=ctx, config=config),
         lambda: build_ceph_cluster(ctx=ctx, config=dict(
                 conf=config.get('conf', {}),
                 branch=config.get('branch',{}),
                 mon_initial_members=config.get('mon_initial_members', None),
                 test_mon_destroy=config.get('test_mon_destroy', None),
                 )),
        ):
        yield

def task(ctx, config):
    """
    Set up and tear down a Ceph cluster.

    For example::

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                stable: bobtail
             mon_initial_members: 1
             only_mon: true
             keep_running: true

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                dev: master
             conf:
                mon:
                   debug mon = 20

        tasks:
        - install:
             extras: yes
        - ssh_keys:
        - ceph-deploy:
             branch:
                testing:
             dmcrypt: yes
             separate_journal_disk: yes

    """
    if config is None:
        config = {}

    assert isinstance(config, dict), \
        "task ceph-deploy only supports a dictionary for configuration"

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('ceph-deploy', {}))

    if config.get('branch') is not None:
        assert isinstance(
            config['branch'], dict), 'branch must be a dictionary'

    log.info('task ceph-deploy with config ' + str(config))

    with contextutil.nested(
        lambda: install_fn.ship_utilities(ctx=ctx, config=None),
        lambda: download_ceph_deploy(ctx=ctx, config=config),
        lambda: build_ceph_cluster(ctx=ctx, config=config),
    ):
        yield

def _run_one_client(ctx, config, role):
    """Spawned task that runs the client"""
    krbd = config.get('krbd', False)
    nbd = config.get('nbd', False)
    testdir = teuthology.get_testdir(ctx)
    (remote,) = ctx.cluster.only(role).remotes.iterkeys()

    args = []
    if krbd or nbd:
        args.append('sudo') # rbd(-nbd) map/unmap need privileges
    args.extend([
        'adjust-ulimits',
        'ceph-coverage',
        '{tdir}/archive/coverage'.format(tdir=testdir)
    ])

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('rbd_fsx', {}))

    if config.get('valgrind'):
        args = teuthology.get_valgrind_args(
            testdir,
            'fsx_{id}'.format(id=role),
            args,
            config.get('valgrind')
        )

    args.extend([
        'ceph_test_librbd_fsx',
        '-d', # debug output for all operations
        '-W', '-R', # mmap doesn't work with rbd
        '-p', str(config.get('progress_interval', 100)), # show progress
        '-P', '{tdir}/archive'.format(tdir=testdir),
        '-r', str(config.get('readbdy',1)),
        '-w', str(config.get('writebdy',1)),
        '-t', str(config.get('truncbdy',1)),
        '-h', str(config.get('holebdy',1)),
        '-l', str(config.get('size', 250000000)),
        '-S', str(config.get('seed', 0)),
        '-N', str(config.get('ops', 1000)),
    ])
    if krbd:
        args.append('-K') # -K enables krbd mode
    if nbd:
        args.append('-M') # -M enables nbd mode
    if config.get('direct_io', False):
        args.append('-Z') # -Z use direct IO
    if not config.get('randomized_striping', True):
        args.append('-U') # -U disables randomized striping
    if not config.get('punch_holes', True):
        args.append('-H') # -H disables discard ops
    if config.get('journal_replay', False):
        args.append('-j') # -j replay all IO events from journal
    args.extend([
        'pool_{pool}'.format(pool=role),
        'image_{image}'.format(image=role),
    ])

    remote.run(args=args)

    def end(self):
        overrides = self.ctx.config.get('overrides', {})
        misc.deep_merge(self.config, overrides.get('check-counter', {}))

        cluster_name = self.config.get('cluster_name', None)
        dry_run = self.config.get('dry_run', False)
        targets = self.config.get('counters', {})

        if cluster_name is None:
            cluster_name = self.ctx.managers.keys()[0]

        for daemon_type, counters in targets.items():
            # List of 'a', 'b', 'c'...
            daemon_ids = list(misc.all_roles_of_type(self.ctx.cluster, daemon_type))
            daemons = dict([(daemon_id,
                             self.ctx.daemons.get_daemon(daemon_type, daemon_id))
                            for daemon_id in daemon_ids])

            seen = set()

            for daemon_id, daemon in daemons.items():
                if not daemon.running():
                    log.info("Ignoring daemon {0}, it isn't running".format(daemon_id))
                    continue
                else:
                    log.debug("Getting stats from {0}".format(daemon_id))

                manager = self.ctx.managers[cluster_name]
                proc = manager.admin_socket(daemon_type, daemon_id, ["perf", "dump"])
                response_data = proc.stdout.getvalue().strip()
                if response_data:
                    perf_dump = json.loads(response_data)
                else:
                    log.warning("No admin socket response from {0}, skipping".format(daemon_id))
                    continue

                for counter in counters:
                    subsys, counter_id = counter.split(".")
                    if subsys not in perf_dump or counter_id not in perf_dump[subsys]:
                        log.warning("Counter '{0}' not found on daemon {1}.{2}".format(
                            counter, daemon_type, daemon_id))
                        continue
                    value = perf_dump[subsys][counter_id]

                    log.info("Daemon {0}.{1} {2}={3}".format(
                        daemon_type, daemon_id, counter, value
                    ))

                    if value > 0:
                        seen.add(counter)

            if not dry_run:
                unseen = set(counters) - set(seen)
                if unseen:
                    raise RuntimeError("The following counters failed to be set "
                                       "on {0} daemons: {1}".format(
                        daemon_type, unseen
                    ))

def task(ctx, config):
    """
    Install packages for a given project.

    tasks:
    - install:
        project: ceph
        branch: bar
    - install:
        project: samba
        branch: foo
        extra_packages: ['samba']

    Overrides are project specific:

    overrides:
      install:
        ceph:
          sha1: ...

    :param ctx: the argparse.Namespace object
    :param config: the config dict
    """
    if config is None:
        config = {}
    assert isinstance(config, dict), \
        "task install only supports a dictionary for configuration"

    project, = config.get('project', 'ceph'),
    log.debug('project %s' % project)
    overrides = ctx.config.get('overrides')
    if overrides:
        install_overrides = overrides.get('install', {})
        teuthology.deep_merge(config, install_overrides.get(project, {}))
    log.debug('config %s' % config)

    flavor = get_flavor(config)
    log.info("Using flavor: %s", flavor)

    ctx.summary['flavor'] = flavor

    with contextutil.nested(
        lambda: install(ctx=ctx, config=dict(
            branch=config.get('branch'),
            tag=config.get('tag'),
            sha1=config.get('sha1'),
            flavor=flavor,
            extra_packages=config.get('extra_packages', []),
            extras=config.get('extras', None),
            wait_for_package=ctx.config.get('wait_for_package', False),
            project=project,
        )),
        lambda: ship_utilities(ctx=ctx, config=None),
    ):
        yield

def task(ctx, config):
    """
    Configures dnsmasq to add cnames for teuthology remotes. The task expects a
    dictionary, where each key is a role. If all cnames for that role use the
    same address as that role, the cnames can be given as a list. For example,
    this entry configures dnsmasq on the remote associated with client.0, adding
    two cnames for the ip address associated with client.0:

        - dnsmasq:
            client.0:
            - client0.example.com
            - c0.example.com

    If the addresses do not all match the given role, a dictionary can be given
    to specify the ip address by its target role. For example:

        - dnsmasq:
            client.0:
              client.0.example.com: client.0
              client.1.example.com: client.1
    """
    # apply overrides
    overrides = config.get('overrides', {})
    misc.deep_merge(config, overrides.get('dnsmasq', {}))

    # multiple roles may map to the same remote, so collect names by remote
    remote_names = {}
    for role, cnames in config.iteritems():
        remote = get_remote_for_role(ctx, role)
        if remote is None:
            raise ConfigError('no remote for role %s' % role)

        names = remote_names.get(remote, {})

        if isinstance(cnames, list):
            # when given a list of cnames, point to local ip
            for cname in cnames:
                names[cname] = remote.ip_address
        elif isinstance(cnames, dict):
            # when given a dict, look up the remote ip for each
            for cname, client in cnames.iteritems():
                r = get_remote_for_role(ctx, client)
                if r is None:
                    raise ConfigError('no remote for role %s' % client)
                names[cname] = r.ip_address

        remote_names[remote] = names

    # run a subtask for each unique remote
    subtasks = []
    for remote, cnames in remote_names.iteritems():
        subtasks.extend([ lambda r=remote, cn=cnames: setup_dnsmasq(r, cn) ])

    with contextutil.nested(*subtasks):
        yield

def reposetup(ctx, config):
    """
    task reposetup
    Sets up calamari repository on all 'osd', 'mon', and 'calamari.' remotes;
     cleans up when done

    calamari.reposetup:
        pkgdir:
        username:
        password:

    Supply the above in an override file if you need to manage the
    secret repo credentials separately from the test definition (likely).

    pkgdir encodes package directory (possibly more than one path component)
    as in https://<username>:<password>@SERVER/<pkgdir>/{deb,rpm}{..}

    """
    overrides = ctx.config.get('overrides', {})
    # XXX deep_merge returns the result, which matters if either is None
    # make sure that doesn't happen
    if config is None:
        config = {'dummy': 'dummy'}
    teuthology.deep_merge(config, overrides.get('calamari.reposetup', {}))

    try:
        pkgdir = config['pkgdir']
        username = config['username']
        password = config['password']
    except KeyError:
        raise RuntimeError('requires pkgdir, username, and password')

    # repo gets installed on any remote with role mon, osd, or calamari
    def needs_repo(role):
        for type in 'mon.', 'osd.', 'calamari.':
            if role.startswith(type):
                return True
        return False

    remotes = _remotes(ctx, needs_repo)
    if remotes is None:
        raise RuntimeError('No roles configured')

    try:
        for rem in remotes:
            log.info(rem)
            keypath = 'http://download.inktank.com/keys/release.asc'
            pkg.install_repokey(rem, keypath)
            pkg.install_repo(rem, 'download.inktank.com', pkgdir,
                             username, password)
        yield

    finally:
        for rem in remotes:
            pkg.remove_repo(rem)

def task(ctx, config):
    """
    Run some s3-tests suite against rgw, verify opslog socket returns data

    Must restrict testing to a particular client::

        tasks:
        - ceph:
        - rgw: [client.0]
        - s3tests: [client.0]

    To pass extra arguments to nose (e.g. to run a certain test)::

        tasks:
        - ceph:
        - rgw: [client.0]
        - s3tests:
            client.0:
              extra_args: ['test_s3:test_object_acl_grand_public_read']
            client.1:
              extra_args: ['--exclude', 'test_100_continue']
    """
    assert (
        config is None or isinstance(config, list) or isinstance(config, dict)
    ), "task s3tests only supports a list or dictionary for configuration"
    all_clients = ["client.{id}".format(id=id_) for id_ in teuthology.all_roles_of_type(ctx.cluster, "client")]
    if config is None:
        config = all_clients
    if isinstance(config, list):
        config = dict.fromkeys(config)
    clients = config.keys()

    overrides = ctx.config.get("overrides", {})
    # merge each client section, not the top level.
    for (client, cconf) in config.iteritems():
        teuthology.deep_merge(cconf, overrides.get("rgw-logsocket", {}))

    log.debug("config is %s", config)

    s3tests_conf = {}
    for client in clients:
        s3tests_conf[client] = ConfigObj(
            indent_type="",
            infile={"DEFAULT": {"port": 7280, "is_secure": "no"}, "fixtures": {}, "s3 main": {}, "s3 alt": {}},
        )

    with contextutil.nested(
        lambda: download(ctx=ctx, config=config),
        lambda: create_users(ctx=ctx, config=dict(clients=clients, s3tests_conf=s3tests_conf)),
        lambda: configure(ctx=ctx, config=dict(clients=config, s3tests_conf=s3tests_conf)),
        lambda: run_tests(ctx=ctx, config=config),
    ):
        yield

def server(ctx, config):
    """
    task server:

    Calamari server setup.  Add role 'calamari.server' to the remote
    that will run the webapp.  'calamari.restapi' role must be present
    to serve as the cluster-api target for calamari-server.  Only one
    of calamari.server and calamari.restapi roles is supported currently.

    For example::

        roles:
        - [calamari.server]
        - [mon.0, calamari.restapi]
        - [osd.0, osd.1]
        tasks:
        - calamari.restapi:
        - calamari.server:
    """
    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('calamari.server', {}))

    remote = _remotes(ctx, lambda r: r.startswith('calamari.server'))
    if not remote:
        raise RuntimeError('No role configured')

    restapi_remote = _remotes(ctx, lambda r: r.startswith('calamari.restapi'))
    if not restapi_remote:
        raise RuntimeError('Must supply calamari.restapi role')

    remote = remote[0]
    restapi_remote = restapi_remote[0]

    try:
        # sqlite3 command is required; on some platforms it's already
        # there and not removable (required for, say yum)
        sqlite_package = pkg.get_package_name('sqlite', remote)
        if sqlite_package and not pkg.install_package(sqlite_package, remote):
            raise RuntimeError('{} install failed'.format(sqlite_package))

        if not pkg.install_package('calamari-server', remote) or \
           not pkg.install_package('calamari-clients', remote) or \
           not _disable_default_nginx(remote) or \
           not _setup_calamari_cluster(remote, restapi_remote):
            raise RuntimeError('Server installation failure')

        log.info('client/server setup complete')
        yield
    finally:
        pkg.remove_package('calamari-server', remote)
        pkg.remove_package('calamari-clients', remote)
        if sqlite_package:
            pkg.remove_package(sqlite_package, remote)

def agent(ctx, config):
    """
    task agent
    calamari.agent: install stats collection
       (for each role of type 'mon.' or 'osd.')

    For example::

        roles:
        - [osd.0, mon.a]
        - [osd.1]
        tasks:
        - calamari.agent:
    """

    log.info('calamari.agent starting')
    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('calamari.agent', {}))

    # agent gets installed on any remote with role mon or osd
    def needs_agent(role):
        for type in 'mon.', 'osd.':
            if role.startswith(type):
                return True
        return False

    remotes = _remotes(ctx, needs_agent)
    if remotes is None:
        raise RuntimeError('No role configured')
    try:
        for rem in remotes:
            log.info('Installing calamari-agent on %s', rem)
            pkg.install_package('calamari-agent', rem)
            server_remote = _remotes(ctx,
                lambda r: r.startswith('calamari.server'))
            if not server_remote:
                raise RuntimeError('No calamari.server role available')
            server_remote = server_remote[0]
            # why isn't shortname available by default?
            serverhost = server_remote.name.split('@')[1]
            log.info('configuring Diamond for {}'.format(serverhost))
            if not _edit_diamond_config(rem, serverhost):
                raise RuntimeError(
                    'Diamond config edit failed on {0}'.format(rem)
                )
        yield
    finally:
            for rem in remotes:
                pkg.remove_package('calamari-agent', rem)

def upgrade_remote_to_config(ctx, config):
    assert config is None or isinstance(config, dict), \
        "install.upgrade only supports a dictionary for configuration"

    project = config.get('project', 'ceph')

    # use 'install' overrides here, in case the upgrade target is left
    # unspecified/implicit.
    install_overrides = ctx.config.get(
        'overrides', {}).get('install', {}).get(project, {})
    log.info('project %s config %s overrides %s', project, config,
             install_overrides)

    # build a normalized remote -> config dict
    remotes = {}
    if 'all' in config:
        for remote in ctx.cluster.remotes.iterkeys():
            remotes[remote] = config.get('all')
    else:
        for role in config.keys():
            remotes_dict = ctx.cluster.only(role).remotes
            if not remotes_dict:
                # This is a regular config argument, not a role
                continue
            remote = remotes_dict.keys()[0]
            if remote in remotes:
                log.warn('remote %s came up twice (role %s)', remote, role)
                continue
            remotes[remote] = config.get(role)

    result = {}
    for remote, node in remotes.iteritems():
        if not node:
            node = {}

        this_overrides = copy.deepcopy(install_overrides)
        if 'sha1' in node or 'tag' in node or 'branch' in node:
            log.info("config contains sha1|tag|branch, "
                     "removing those keys from override")
            this_overrides.pop('sha1', None)
            this_overrides.pop('tag', None)
            this_overrides.pop('branch', None)
        teuthology.deep_merge(node, this_overrides)
        log.info('remote %s config %s', remote, node)
        node['project'] = project

        result[remote] = node

    return result

def task(ctx, config):
    if config is None:
        config = {}
    assert isinstance(config, dict), "task hadoop config must be dictionary"

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('hadoop', {}))

    tasks = [
        lambda: install_hadoop(ctx=ctx, config=config),
        lambda: start_hadoop(ctx=ctx, config=config),
    ]

    with contextutil.nested(*tasks):
        yield

 def apply_overrides(self):
     """
     Look for an 'overrides' dict in self.ctx.config; look inside that for a
     dict with the same name as this task. Override any settings in
     self.config with those overrides
     """
     all_overrides = self.ctx.config.get('overrides', dict())
     if not all_overrides:
         return
     task_overrides = all_overrides.get(self.name)
     if task_overrides:
         self.log.debug(
             "Applying overrides for task {name}: {overrides}".format(
                 name=self.name, overrides=task_overrides)
         )
         deep_merge(self.config, task_overrides)

def apply_overrides(ctx, config):
    if config is None:
        config = {}
    else:
        config = copy.deepcopy(config)

    assert isinstance(config, dict), \
        "task install only supports a dictionary for configuration"

    project, = config.get('project', 'ceph'),
    log.debug('project %s' % project)
    overrides = ctx.config.get('overrides')
    if overrides:
        install_overrides = overrides.get('install', {})
        misc.deep_merge(config, install_overrides.get(project, {}))
    return config

def get_client_configs(ctx, config):
    """
    Get a map of the configuration for each FUSE client in the configuration by
    combining the configuration of the current task with any global overrides.

    :param ctx: Context instance
    :param config: configuration for this task
    :return: dict of client name to config or to None
    """
    if config is None:
        config = dict(('client.{id}'.format(id=id_), None)
                      for id_ in teuthology.all_roles_of_type(ctx.cluster, 'client'))
    elif isinstance(config, list):
        config = dict((name, None) for name in config)

    overrides = ctx.config.get('overrides', {})
    teuthology.deep_merge(config, overrides.get('ceph-fuse', {}))

    return config

def get_refspec_after_overrides(config, overrides):
    # mimic the behavior of the "install" task, where the "overrides" are
    # actually the defaults of that task. in other words, if none of "sha1",
    # "tag", or "branch" is specified by a "workunit" tasks, we will update
    # it with the information in the "workunit" sub-task nested in "overrides".
    overrides = copy.deepcopy(overrides.get('workunit', {}))
    refspecs = {'branch': Branch, 'tag': Refspec, 'sha1': Refspec}
    if any(map(lambda i: i in config, refspecs.iterkeys())):
        for i in refspecs.iterkeys():
            overrides.pop(i, None)
    misc.deep_merge(config, overrides)

    for spec, cls in refspecs.iteritems():
        refspec = config.get(spec)
        if refspec:
            refspec = cls(refspec)
            break
    if refspec is None:
        refspec = Head()
    return refspec

    def setup(self):
        super(RGWMultisiteTests, self).setup()

        overrides = self.ctx.config.get('overrides', {})
        misc.deep_merge(self.config, overrides.get('rgw-multisite-tests', {}))

        if not self.ctx.rgw_multisite:
            raise ConfigError('rgw-multisite-tests must run after the rgw-multisite task')
        realm = self.ctx.rgw_multisite.realm
        master_zone = realm.meta_master_zone()

        # create the test user
        log.info('creating test user..')
        user = multisite.User('rgw-multisite-test-user')
        user.create(master_zone, ['--display-name', 'Multisite Test User',
                                  '--gen-access-key', '--gen-secret'])

        config = self.config.get('config', {})
        tests.init_multi(realm, user, tests.Config(**config))
        tests.realm_meta_checkpoint(realm)

def normalize_and_apply_overrides(ctx, config, overrides):
    """
    kernel task config is hierarchical and needs to be transformed into
    a normal form, see normalize_config() for details.  Applying overrides is
    also more involved compared to other tasks because of the number of ways
    a version of the kernel to install can be specified.

    Returns a (normalized config, timeout) tuple.

    :param ctx: Context
    :param config: Configuration
    """
    timeout = TIMEOUT_DEFAULT
    if 'timeout' in config:
        timeout = config.pop('timeout')
    config = normalize_config(ctx, config)
    log.debug('normalized config %s' % config)

    if 'timeout' in overrides:
        timeout = overrides.pop('timeout')
    if overrides:
        overrides = normalize_config(ctx, overrides)
        log.debug('normalized overrides %s' % overrides)

        # Handle a case when a version specified with one type of version key
        # is overridden by a version specified with another type of version key
        # (e.g. 'branch: foo' is overridden with 'tag: bar').  To be able to
        # use deep_merge(), drop all version keys from the original config if
        # the corresponding override has a version key.
        for role, role_config in config.iteritems():
            if (role in overrides and
                    any(k in overrides[role] for k in VERSION_KEYS)):
                for k in VERSION_KEYS:
                    role_config.pop(k, None)
        teuthology.deep_merge(config, overrides)

    return (config, timeout)