From: Zack Cerza <zack@cerza.org>
Date: Thu, 27 Mar 2014 16:35:28 +0000 (-0500)
Subject: Revert "Lines formerly of the form '(remote,) = ctx.cluster.only(role).remotes.keys()'"
X-Git-Tag: 1.1.0~1558
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=158f9ba1ff4c638cbbb692403a00cb0ff85fbd24;p=teuthology.git

Revert "Lines formerly of the form '(remote,) = ctx.cluster.only(role).remotes.keys()'"

This reverts commit d693b3f8950ffd1f2492a4db0f8234fee31f00f0.
---

diff --git a/teuthology/misc.py b/teuthology/misc.py
index 49220ee41..c075e56d6 100644
--- a/teuthology/misc.py
+++ b/teuthology/misc.py
@@ -987,7 +987,7 @@ def get_clients(ctx, roles):
         PREFIX = 'client.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         yield (id_, remote)
 
 
@@ -1211,21 +1211,3 @@ def get_multi_machine_types(machinetype):
     if not machinetypes:
         machinetypes.append(machinetype)
     return machinetypes
-
-
-def get_single_remote_value(ctx, role):
-    """
-    Return the first (and hopefully only) remotes value for this role.
-    Added log.errors so that error conditions are not as confusing as
-    they used to be.  This code still throws a value error so that the
-    stack is dumped and the location of the fault can be found easily.
-    """
-    keyz = ctx.cluster.only(role).remotes.keys()
-    if len(keyz) == 0:
-        log.error("Role list for %s is empty" % role)
-    if len(keyz) > 1:
-        bad_keys = ", ".join(keyz)
-        log.error("Only one remote value should exist for %s -- %s found" %
-                role, bad_keys)
-    (remote,) = keyz
-    return remote
diff --git a/teuthology/task/admin_socket.py b/teuthology/task/admin_socket.py
index 4b01fae8c..20a670122 100644
--- a/teuthology/task/admin_socket.py
+++ b/teuthology/task/admin_socket.py
@@ -123,7 +123,7 @@ def _run_tests(ctx, client, tests):
     """
     testdir = teuthology.get_testdir(ctx)
     log.debug('Running admin socket tests on %s', client)
-    remote = teuthology.get_single_remote_value(ctx, client)
+    (remote,) = ctx.cluster.only(client).remotes.iterkeys()
     socket_path = '/var/run/ceph/ceph-{name}.asok'.format(name=client)
     overrides = ctx.config.get('overrides', {}).get('admin_socket', {})
 
diff --git a/teuthology/task/autotest.py b/teuthology/task/autotest.py
index dde2950bf..24a7675df 100644
--- a/teuthology/task/autotest.py
+++ b/teuthology/task/autotest.py
@@ -43,7 +43,7 @@ def task(ctx, config):
     testdir = teuthology.get_testdir(ctx)
     with parallel() as p:
         for role in config.iterkeys():
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             p.spawn(_download, testdir, remote)
 
     log.info('Making a separate scratch dir for every client...')
@@ -52,7 +52,7 @@ def task(ctx, config):
         PREFIX = 'client.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         mnt = os.path.join(testdir, 'mnt.{id}'.format(id=id_))
         scratch = os.path.join(mnt, 'client.{id}'.format(id=id_))
         remote.run(
@@ -69,7 +69,7 @@ def task(ctx, config):
 
     with parallel() as p:
         for role, tests in config.iteritems():
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             p.spawn(_run_tests, testdir, remote, role, tests)
 
 def _download(testdir, remote):
diff --git a/teuthology/task/calamari.py b/teuthology/task/calamari.py
index b5b1d44dd..f3c1495f6 100644
--- a/teuthology/task/calamari.py
+++ b/teuthology/task/calamari.py
@@ -108,7 +108,7 @@ def _setup_calamari_cluster(remote, restapi_remote):
 
 
 def _remotes(ctx, selector):
-    return teuthology.get_single_remote_value(ctx, selector)
+    return ctx.cluster.only(selector).remotes.keys()
 
 """
 Tasks
diff --git a/teuthology/task/ceph-deploy.py b/teuthology/task/ceph-deploy.py
index 3a676c0c5..aec9d1b2c 100644
--- a/teuthology/task/ceph-deploy.py
+++ b/teuthology/task/ceph-deploy.py
@@ -65,7 +65,7 @@ def is_healthy(ctx, config):
     """Wait until a Ceph cluster is healthy."""
     testdir = teuthology.get_testdir(ctx)
     ceph_admin = teuthology.get_first_mon(ctx, config)
-    remote = teuthology.get_single_remote_value(ctx, ceph_admin)
+    (remote,) = ctx.cluster.only(ceph_admin).remotes.keys()
     max_tries = 90  # 90 tries * 10 secs --> 15 minutes
     tries = 0
     while True:
@@ -135,7 +135,7 @@ def execute_ceph_deploy(ctx, config, cmd):
     testdir = teuthology.get_testdir(ctx)
     ceph_admin = teuthology.get_first_mon(ctx, config)
     exec_cmd = cmd
-    remote = teuthology.get_single_remote_value(ctx, ceph_admin)
+    (remote,) = ctx.cluster.only(ceph_admin).remotes.iterkeys()
     proc = remote.run(
         args = [
             'cd',
@@ -190,7 +190,7 @@ def build_ceph_cluster(ctx, config):
         testdir = teuthology.get_testdir(ctx)
         conf_path = '{tdir}/ceph-deploy/ceph.conf'.format(tdir=testdir)
         first_mon = teuthology.get_first_mon(ctx, config)
-        remote = teuthology.get_single_remote_value(ctx, first_mon)
+        (remote,) = ctx.cluster.only(first_mon).remotes.keys()
 
         lines = None
         if config.get('conf') is not None:
@@ -279,7 +279,7 @@ def build_ceph_cluster(ctx, config):
             conf_path = '/etc/ceph/ceph.conf'
             admin_keyring_path = '/etc/ceph/ceph.client.admin.keyring'
             first_mon = teuthology.get_first_mon(ctx, config)
-            mon0_remote = teuthology.get_single_remote_value(ctx, first_mon)
+            (mon0_remote,) = ctx.cluster.only(first_mon).remotes.keys()
             conf_data = teuthology.get_file(
                 remote=mon0_remote,
                 path=conf_path,
diff --git a/teuthology/task/ceph.py b/teuthology/task/ceph.py
index c1d7f6ed7..5a695b570 100644
--- a/teuthology/task/ceph.py
+++ b/teuthology/task/ceph.py
@@ -565,7 +565,7 @@ def cluster(ctx, config):
             keyring_path,
             ],
         )
-    mon0_remote = teuthology.get_single_remote_value(ctx, firstmon)
+    (mon0_remote,) = ctx.cluster.only(firstmon).remotes.keys()
     fsid = teuthology.create_simple_monmap(
         ctx,
         remote=mon0_remote,
@@ -904,7 +904,7 @@ def cluster(ctx, config):
         ctx.summary['success'] = False
         raise
     finally:
-        mon0_remote = teuthology.get_single_remote_value(ctx, firstmon)
+        (mon0_remote,) = ctx.cluster.only(firstmon).remotes.keys()
 
         log.info('Checking cluster log for badness...')
         def first_in_ceph_log(pattern, excludes):
@@ -1185,7 +1185,7 @@ def run_daemon(ctx, config, type_):
 
     if type_ == 'mds':
         firstmon = teuthology.get_first_mon(ctx, config)
-        mon0_remote = teuthology.get_single_remote_value(ctx, firstmon)
+        (mon0_remote,) = ctx.cluster.only(firstmon).remotes.keys()
 
         mon0_remote.run(args=[
             'adjust-ulimits',
@@ -1208,7 +1208,7 @@ def healthy(ctx, config):
     """
     log.info('Waiting until ceph is healthy...')
     firstmon = teuthology.get_first_mon(ctx, config)
-    mon0_remote = teuthology.get_single_remote_value(ctx, firstmon)
+    (mon0_remote,) = ctx.cluster.only(firstmon).remotes.keys()
     teuthology.wait_until_osds_up(
         ctx,
         cluster=ctx.cluster,
@@ -1228,7 +1228,7 @@ def wait_for_osds_up(ctx, config):
     """
     log.info('Waiting until ceph osds are all up...')
     firstmon = teuthology.get_first_mon(ctx, config)
-    mon0_remote = teuthology.get_single_remote_value(ctx, firstmon)
+    (mon0_remote,) = ctx.cluster.only(firstmon).remotes.keys()
     teuthology.wait_until_osds_up(
         ctx,
         cluster=ctx.cluster,
@@ -1245,7 +1245,7 @@ def wait_for_mon_quorum(ctx, config):
 
     assert isinstance(config, list)
     firstmon = teuthology.get_first_mon(ctx, config)
-    remote = teuthology.get_single_remote_value(ctx, firstmon)
+    (remote,) = ctx.cluster.only(firstmon).remotes.keys()
     while True:
         r = remote.run(
             args=[
diff --git a/teuthology/task/ceph_manager.py b/teuthology/task/ceph_manager.py
index c1973852f..3952950b2 100644
--- a/teuthology/task/ceph_manager.py
+++ b/teuthology/task/ceph_manager.py
@@ -1190,8 +1190,7 @@ class CephManager:
         or by stopping.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remotes_value(self.ctx,
-                    'osd.{o}'.format(o=osd))
+            (remote,) = self.ctx.cluster.only('osd.{o}'.format(o=osd)).remotes.iterkeys()
             self.log('kill_osd on osd.{o} doing powercycle of {s}'.format(o=osd, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_off()
@@ -1213,8 +1212,7 @@ class CephManager:
         or by restarting.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remotes_value(self.ctx,
-                    'osd.{o}'.format(o=osd))
+            (remote,) = self.ctx.cluster.only('osd.{o}'.format(o=osd)).remotes.iterkeys()
             self.log('kill_osd on osd.{o} doing powercycle of {s}'.format(o=osd, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_on()
@@ -1260,8 +1258,7 @@ class CephManager:
         or by doing a stop.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remote_value(self.ctx,
-                    'mon.{m}'.format(m=mon))
+            (remote,) = self.ctx.cluster.only('mon.{m}'.format(m=mon)).remotes.iterkeys()
             self.log('kill_mon on mon.{m} doing powercycle of {s}'.format(m=mon, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_off()
@@ -1274,8 +1271,7 @@ class CephManager:
         or by doing a normal restart.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remote_value(self.ctx,
-                    'mon.{m}'.format(m=mon))
+            (remote,) = self.ctx.cluster.only('mon.{m}'.format(m=mon)).remotes.iterkeys()
             self.log('revive_mon on mon.{m} doing powercycle of {s}'.format(m=mon, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_on()
@@ -1328,8 +1324,7 @@ class CephManager:
         Powercyle if set in config, otherwise just stop.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remote_value(self.ctx,
-                    'mds.{m}'.format(m=mds))
+            (remote,) = self.ctx.cluster.only('mds.{m}'.format(m=mds)).remotes.iterkeys()
             self.log('kill_mds on mds.{m} doing powercycle of {s}'.format(m=mds, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_off()
@@ -1349,8 +1344,7 @@ class CephManager:
         and then restart (using --hot-standby if specified.
         """
         if self.config.get('powercycle'):
-            remote = teuthology.get_single_remote_value(self.ctx,
-                    'mds.{m}'.format(m=mds))
+            (remote,) = self.ctx.cluster.only('mds.{m}'.format(m=mds)).remotes.iterkeys()
             self.log('revive_mds on mds.{m} doing powercycle of {s}'.format(m=mds, s=remote.name))
             assert remote.console is not None, "powercycling requested but RemoteConsole is not initialized.  Check ipmi config."
             remote.console.power_on()
diff --git a/teuthology/task/common_fs_utils.py b/teuthology/task/common_fs_utils.py
index 3c79a2642..b963e98d4 100644
--- a/teuthology/task/common_fs_utils.py
+++ b/teuthology/task/common_fs_utils.py
@@ -40,7 +40,7 @@ def generic_mkfs(ctx, config, devname_rtn):
     for role, properties in images:
         if properties is None:
             properties = {}
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
         image = properties.get('image_name', default_image_name(role))
         fs_type = properties.get('fs_type', 'ext3')
         remote.run(
@@ -90,7 +90,7 @@ def generic_mount(ctx, config, devname_rtn):
     for role, image in role_images:
         if image is None:
             image = default_image_name(role)
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
         id_ = strip_client_prefix(role)
         mnt = mnt_template.format(tdir=testdir, id=id_)
         mounted.append((remote, mnt))
diff --git a/teuthology/task/cram.py b/teuthology/task/cram.py
index 8627e02a6..05824d26a 100644
--- a/teuthology/task/cram.py
+++ b/teuthology/task/cram.py
@@ -51,7 +51,7 @@ def task(ctx, config):
 
     try:
         for client, tests in clients.iteritems():
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.iterkeys()
             client_dir = '{tdir}/archive/cram.{role}'.format(tdir=testdir, role=client)
             remote.run(
                 args=[
@@ -77,7 +77,7 @@ def task(ctx, config):
                 p.spawn(_run_tests, ctx, role)
     finally:
         for client, tests in clients.iteritems():
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.iterkeys()
             client_dir = '{tdir}/archive/cram.{role}'.format(tdir=testdir, role=client)
             test_files = set([test.rsplit('/', 1)[1] for test in tests])
 
@@ -115,7 +115,7 @@ def _run_tests(ctx, role):
     PREFIX = 'client.'
     assert role.startswith(PREFIX)
     id_ = role[len(PREFIX):]
-    remote = teuthology.get_single_remote_value(ctx, role)
+    (remote,) = ctx.cluster.only(role).remotes.iterkeys()
     ceph_ref = ctx.summary.get('ceph-sha1', 'master')
 
     testdir = teuthology.get_testdir(ctx)
diff --git a/teuthology/task/die_on_err.py b/teuthology/task/die_on_err.py
index c1c198f8f..1dfd37073 100644
--- a/teuthology/task/die_on_err.py
+++ b/teuthology/task/die_on_err.py
@@ -20,7 +20,7 @@ def task(ctx, config):
         config = {}
 
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     num_osds = teuthology.num_instances_of_type(ctx.cluster, 'osd')
     log.info('num_osds is %s' % num_osds)
@@ -38,7 +38,7 @@ def task(ctx, config):
 
     while True:
         for i in range(num_osds):
-            osd_remote = teuthology.get_single_remote_value(ctx, 'osd.%d' % i)
+            (osd_remote,) = ctx.cluster.only('osd.%d' % i).remotes.iterkeys()
             p = osd_remote.run(
                 args = [ 'test', '-e', '{tdir}/err'.format(tdir=testdir) ],
                 wait=True,
diff --git a/teuthology/task/divergent_priors.py b/teuthology/task/divergent_priors.py
index 9767a02b1..432614f23 100644
--- a/teuthology/task/divergent_priors.py
+++ b/teuthology/task/divergent_priors.py
@@ -25,7 +25,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'divergent_priors task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/dump_stuck.py b/teuthology/task/dump_stuck.py
index 0b41021ee..9e1780f01 100644
--- a/teuthology/task/dump_stuck.py
+++ b/teuthology/task/dump_stuck.py
@@ -57,7 +57,7 @@ def task(ctx, config):
 
     timeout = 60
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/exec.py b/teuthology/task/exec.py
index af67eb9d1..f951f77a8 100644
--- a/teuthology/task/exec.py
+++ b/teuthology/task/exec.py
@@ -34,7 +34,7 @@ def task(ctx, config):
         config = dict((id_, a) for id_ in roles)
 
     for role, ls in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         log.info('Running commands on role %s host %s', role, remote.name)
         for c in ls:
             c.replace('$TESTDIR', testdir)
diff --git a/teuthology/task/filestore_idempotent.py b/teuthology/task/filestore_idempotent.py
index 3621fd4cf..d33ad6458 100644
--- a/teuthology/task/filestore_idempotent.py
+++ b/teuthology/task/filestore_idempotent.py
@@ -32,7 +32,7 @@ def task(ctx, config):
 
     # just use the first client...
     client = clients[0];
-    remote = teuthology.get_single_remote_value(ctx, client)
+    (remote,) = ctx.cluster.only(client).remotes.iterkeys()
 
     testdir = teuthology.get_testdir(ctx)
 
diff --git a/teuthology/task/install.py b/teuthology/task/install.py
index 6459a2834..eaf8de9d5 100644
--- a/teuthology/task/install.py
+++ b/teuthology/task/install.py
@@ -1049,7 +1049,7 @@ def upgrade(ctx, config):
             remotes[remote] = config.get('all')
     else:
         for role in config.keys():
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
             if remote in remotes:
                 log.warn('remote %s came up twice (role %s)', remote, role)
                 continue
diff --git a/teuthology/task/kernel.py b/teuthology/task/kernel.py
index b9b0acb40..7d63190dc 100644
--- a/teuthology/task/kernel.py
+++ b/teuthology/task/kernel.py
@@ -189,7 +189,7 @@ def install_firmware(ctx, config):
         if config[role].find('distro') >= 0:
             log.info('Skipping firmware on distro kernel');
             return
-        role_remote = teuthology.get_single_remote_value(ctx, role)
+        (role_remote,) = ctx.cluster.only(role).remotes.keys()
         log.info('Installing linux-firmware on {role}...'.format(role=role))
         role_remote.run(
             args=[
@@ -239,7 +239,7 @@ def download_deb(ctx, config):
     procs = {}
     #Don't need to download distro kernels
     for role, src in config.iteritems():
-        role_remote = teuthology.get_single_remote_value(ctx, role)
+        (role_remote,) = ctx.cluster.only(role).remotes.keys()
 	if src.find('distro') >= 0:
             log.info('Installing newest kernel distro');
             return
@@ -331,7 +331,7 @@ def install_and_reboot(ctx, config):
     procs = {}
     kernel_title = ''
     for role, src in config.iteritems():
-        role_remote = teuthology.get_single_remote_value(ctx, role)
+        (role_remote,) = ctx.cluster.only(role).remotes.keys()
         if src.find('distro') >= 0:
             log.info('Installing distro kernel on {role}...'.format(role=role))
             install_distro_kernel(role_remote)
@@ -480,7 +480,7 @@ def enable_disable_kdb(ctx, config):
     :param config: Configuration
     """
     for role, enable in config.iteritems():
-        role_remote = teuthology.get_single_remote_value(ctx, role)
+        (role_remote,) = ctx.cluster.only(role).remotes.keys()
         if "mira" in role_remote.name:
             serialdev = "ttyS2"
         else:
@@ -552,7 +552,7 @@ def need_to_install_distro(ctx, role):
     and compares against current (uname -r) and returns true if newest != current.
     Similar check for deb.
     """
-    role_remote = teuthology.get_single_remote_value(ctx, role)
+    (role_remote,) = ctx.cluster.only(role).remotes.keys()
     system_type = teuthology.get_system_type(role_remote)
     output, err_mess = StringIO(), StringIO()
     role_remote.run(args=['uname', '-r' ], stdout=output, stderr=err_mess )
diff --git a/teuthology/task/lockfile.py b/teuthology/task/lockfile.py
index 68144d003..10ac1e8e9 100644
--- a/teuthology/task/lockfile.py
+++ b/teuthology/task/lockfile.py
@@ -78,7 +78,7 @@ def task(ctx, config):
         files = set(files)
         lock_procs = list()
         for client in clients:
-            client_remote = teuthology.get_single_remote_value(ctx, client)
+            (client_remote,) = ctx.cluster.only(client).remotes.iterkeys()
             log.info("got a client remote")
             (_, _, client_id) = client.partition('.')
             filepath = os.path.join(testdir, 'mnt.{id}'.format(id=client_id), op["lockfile"])
@@ -111,7 +111,7 @@ def task(ctx, config):
         # create the files to run these locks on
         client = clients.pop()
         clients.add(client)
-        client_remote = teuthology.get_single_remote_value(ctx, client)
+        (client_remote,) = ctx.cluster.only(client).remotes.iterkeys()
         (_, _, client_id) = client.partition('.')
         file_procs = list()
         for lockfile in files:
@@ -168,7 +168,7 @@ def task(ctx, config):
                 greenlet.kill(block=True)
 
         for client in clients:
-            client_remote  = teuthology.get_single_remote_value(ctx, client)
+            (client_remote,)  = ctx.cluster.only(client).remotes.iterkeys()
             (_, _, client_id) = client.partition('.')
             filepath = os.path.join(testdir, 'mnt.{id}'.format(id=client_id), op["lockfile"])
             proc = client_remote.run(
@@ -190,7 +190,7 @@ def lock_one(op, ctx):
     timeout = None
     proc = None
     result = None
-    client_remote  = teuthology.get_single_remote_value(ctx, op['client'])
+    (client_remote,)  = ctx.cluster.only(op['client']).remotes.iterkeys()
     (_, _, client_id) = op['client'].partition('.')
     testdir = teuthology.get_testdir(ctx)
     filepath = os.path.join(testdir, 'mnt.{id}'.format(id=client_id), op["lockfile"])
diff --git a/teuthology/task/lost_unfound.py b/teuthology/task/lost_unfound.py
index 379e75906..700a300bf 100644
--- a/teuthology/task/lost_unfound.py
+++ b/teuthology/task/lost_unfound.py
@@ -19,7 +19,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'lost_unfound task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/manypools.py b/teuthology/task/manypools.py
index 699c41ae9..32b9d562b 100644
--- a/teuthology/task/manypools.py
+++ b/teuthology/task/manypools.py
@@ -39,8 +39,7 @@ def task(ctx, config):
     log.info('got client_roles={client_roles_}'.format(client_roles_=client_roles))
     for role in client_roles:
         log.info('role={role_}'.format(role_=role))
-        creator_remote = teuthology.get_single_remote_value(ctx,
-                'client.{id}'.format(id=role))
+        (creator_remote, ) = ctx.cluster.only('client.{id}'.format(id=role)).remotes.iterkeys()
         creator_remotes.append((creator_remote, 'client.{id}'.format(id=role)))
 
     remaining_pools = poolnum
diff --git a/teuthology/task/mds_creation_failure.py b/teuthology/task/mds_creation_failure.py
index b2ba6b342..a3d052fb9 100644
--- a/teuthology/task/mds_creation_failure.py
+++ b/teuthology/task/mds_creation_failure.py
@@ -23,8 +23,7 @@ def task(ctx, config):
         raise RuntimeError("This task requires exactly one MDS")
 
     mds_id = mdslist[0]
-    mds_remote = misc.get_single_remote_value(ctx,
-            'mds.{_id}'.format(_id=mds_id))
+    (mds_remote,) = ctx.cluster.only('mds.{_id}'.format(_id=mds_id)).remotes.iterkeys()
     manager = ceph_manager.CephManager(
         mds_remote, ctx=ctx, logger=log.getChild('ceph_manager'),
     )
diff --git a/teuthology/task/mds_thrash.py b/teuthology/task/mds_thrash.py
index 54f9a545e..c60b741a4 100644
--- a/teuthology/task/mds_thrash.py
+++ b/teuthology/task/mds_thrash.py
@@ -276,8 +276,7 @@ def task(ctx, config):
     max_thrashers = config.get('max_thrash', 1)
     thrashers = {}
 
-    first = teuthology.get_single_remote_value(ctx,
-            'mds.{_id}'.format(_id=mdslist[0]))
+    (first,) = ctx.cluster.only('mds.{_id}'.format(_id=mdslist[0])).remotes.iterkeys()
     manager = ceph_manager.CephManager(
         first, ctx=ctx, logger=log.getChild('ceph_manager'),
     )
diff --git a/teuthology/task/mon_clock_skew_check.py b/teuthology/task/mon_clock_skew_check.py
index e71f75fe8..891e6ec48 100644
--- a/teuthology/task/mon_clock_skew_check.py
+++ b/teuthology/task/mon_clock_skew_check.py
@@ -240,7 +240,7 @@ def task(ctx, config):
         'mon_clock_skew_check task only accepts a dict for configuration'
     log.info('Beginning mon_clock_skew_check...')
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     manager = ceph_manager.CephManager(
         mon,
         ctx=ctx,
diff --git a/teuthology/task/mon_recovery.py b/teuthology/task/mon_recovery.py
index a593f262c..bfa2cdf78 100644
--- a/teuthology/task/mon_recovery.py
+++ b/teuthology/task/mon_recovery.py
@@ -17,7 +17,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/mon_thrash.py b/teuthology/task/mon_thrash.py
index c75d20bb9..7dc7caad8 100644
--- a/teuthology/task/mon_thrash.py
+++ b/teuthology/task/mon_thrash.py
@@ -324,7 +324,7 @@ def task(ctx, config):
         'mon_thrash task requires at least 3 monitors'
     log.info('Beginning mon_thrash...')
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     manager = ceph_manager.CephManager(
         mon,
         ctx=ctx,
diff --git a/teuthology/task/mpi.py b/teuthology/task/mpi.py
index 22d048c85..6d2381ee5 100644
--- a/teuthology/task/mpi.py
+++ b/teuthology/task/mpi.py
@@ -70,25 +70,23 @@ def task(ctx, config):
     if 'nodes' in config:
         if isinstance(config['nodes'], basestring) and config['nodes'] == 'all':
             for role in  teuthology.all_roles(ctx.cluster):
-                remote = teuthology.get_single_remote_value(ctx,role)
+                (remote,) = ctx.cluster.only(role).remotes.iterkeys()
                 ip,port = remote.ssh.get_transport().getpeername()
                 hosts.append(ip)
                 remotes.append(remote)
-            master_remote = teuthology.get_single_remote_value(ctx,
-                    config['nodes'][0])
+            (master_remote,) = ctx.cluster.only(config['nodes'][0]).remotes.iterkeys()
         elif isinstance(config['nodes'], list):
             for role in config['nodes']:
-                remote = teuthology.get_single_remote_value(ctx, role)
+                (remote,) = ctx.cluster.only(role).remotes.iterkeys()
                 ip,port = remote.ssh.get_transport().getpeername()
                 hosts.append(ip)
                 remotes.append(remote)
-            master_remote = teuthology.get_single_remote_value(ctx,
-                    config['nodes'][0])
+            (master_remote,) = ctx.cluster.only(config['nodes'][0]).remotes.iterkeys()
     else:
         roles = ['client.{id}'.format(id=id_) for id_ in teuthology.all_roles_of_type(ctx.cluster, 'client')]
-        master_remote = teuthology.get_single_remote_value(ctx, roles[0])
+        (master_remote,) = ctx.cluster.only(roles[0]).remotes.iterkeys()
         for role in roles:
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
             ip,port = remote.ssh.get_transport().getpeername()
             hosts.append(ip)
             remotes.append(remote)
diff --git a/teuthology/task/object_source_down.py b/teuthology/task/object_source_down.py
index 26e936d18..1696c5521 100644
--- a/teuthology/task/object_source_down.py
+++ b/teuthology/task/object_source_down.py
@@ -17,7 +17,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'lost_unfound task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/omapbench.py b/teuthology/task/omapbench.py
index 0d07c5d90..7d2535453 100644
--- a/teuthology/task/omapbench.py
+++ b/teuthology/task/omapbench.py
@@ -52,7 +52,7 @@ def task(ctx, config):
         PREFIX = 'client.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         proc = remote.run(
             args=[
                 "/bin/sh", "-c",
diff --git a/teuthology/task/osd_backfill.py b/teuthology/task/osd_backfill.py
index 4c5ad7ad2..d80ea22ef 100644
--- a/teuthology/task/osd_backfill.py
+++ b/teuthology/task/osd_backfill.py
@@ -38,7 +38,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'thrashosds task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     
     num_osds = teuthology.num_instances_of_type(ctx.cluster, 'osd')
     log.info('num_osds is %s' % num_osds)
diff --git a/teuthology/task/osd_failsafe_enospc.py b/teuthology/task/osd_failsafe_enospc.py
index cf33cadfb..39b5b5c53 100644
--- a/teuthology/task/osd_failsafe_enospc.py
+++ b/teuthology/task/osd_failsafe_enospc.py
@@ -32,7 +32,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'osd_failsafe_enospc task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/osd_recovery.py b/teuthology/task/osd_recovery.py
index f7c4b838c..1ff17335b 100644
--- a/teuthology/task/osd_recovery.py
+++ b/teuthology/task/osd_recovery.py
@@ -38,7 +38,7 @@ def task(ctx, config):
         'task only accepts a dict for configuration'
     testdir = teuthology.get_testdir(ctx)
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     
     num_osds = teuthology.num_instances_of_type(ctx.cluster, 'osd')
     log.info('num_osds is %s' % num_osds)
@@ -119,7 +119,7 @@ def test_incomplete_pgs(ctx, config):
     assert isinstance(config, dict), \
         'task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     num_osds = teuthology.num_instances_of_type(ctx.cluster, 'osd')
     log.info('num_osds is %s' % num_osds)
diff --git a/teuthology/task/peer.py b/teuthology/task/peer.py
index 9b233a755..8006c3812 100644
--- a/teuthology/task/peer.py
+++ b/teuthology/task/peer.py
@@ -19,7 +19,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'peer task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/peering_speed_test.py b/teuthology/task/peering_speed_test.py
index 8db4a5dba..6c885f1c9 100644
--- a/teuthology/task/peering_speed_test.py
+++ b/teuthology/task/peering_speed_test.py
@@ -26,7 +26,7 @@ def setup(ctx, config):
     Setup peering test on remotes.
     """
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     ctx.manager = ceph_manager.CephManager(
         mon,
         ctx=ctx,
diff --git a/teuthology/task/pexec.py b/teuthology/task/pexec.py
index 02d84a1c0..742ac0010 100644
--- a/teuthology/task/pexec.py
+++ b/teuthology/task/pexec.py
@@ -68,16 +68,15 @@ def _generate_remotes(ctx, config):
     elif 'clients' in config:
         ls = config['clients']
         for role in teuthology.all_roles_of_type(ctx.cluster, 'client'):
-            remote = teuthology.get_single_remote_value(ctx,
-                    'client.{r}'.format(r=role))
+            (remote,) = ctx.cluster.only('client.{r}'.format(r=role)).remotes.iterkeys()
             yield (remote, ls)
         del config['clients']
         for role, ls in config.iteritems():
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
             yield (remote, ls)
     else:
         for role, ls in config.iteritems():
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
             yield (remote, ls)
 
 def task(ctx, config):
diff --git a/teuthology/task/qemu.py b/teuthology/task/qemu.py
index 423e04af8..db93107a9 100644
--- a/teuthology/task/qemu.py
+++ b/teuthology/task/qemu.py
@@ -26,7 +26,7 @@ def create_dirs(ctx, config):
     testdir = teuthology.get_testdir(ctx)
     for client, client_config in config.iteritems():
         assert 'test' in client_config, 'You must specify a test to run'
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         remote.run(
             args=[
                 'install', '-d', '-m0755', '--',
@@ -39,7 +39,7 @@ def create_dirs(ctx, config):
     finally:
         for client, client_config in config.iteritems():
             assert 'test' in client_config, 'You must specify a test to run'
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.keys()
             remote.run(
                 args=[
                     'rmdir', '{tdir}/qemu'.format(tdir=testdir), run.Raw('||'), 'true',
@@ -84,7 +84,7 @@ def generate_iso(ctx, config):
   /mnt/cdrom/test.sh > /mnt/log/test.log 2>&1 && touch /mnt/log/success
 """ + test_teardown
 
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         teuthology.write_file(remote, userdata_path, StringIO(user_data))
 
         with file(os.path.join(src_dir, 'metadata.yaml'), 'rb') as f:
@@ -114,7 +114,7 @@ def generate_iso(ctx, config):
         yield
     finally:
         for client in config.iterkeys():
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.keys()
             remote.run(
                 args=[
                     'rm', '-f',
@@ -131,7 +131,7 @@ def download_image(ctx, config):
     log.info('downloading base image')
     testdir = teuthology.get_testdir(ctx)
     for client, client_config in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         base_file = '{tdir}/qemu/base.{client}.qcow2'.format(tdir=testdir, client=client)
         remote.run(
             args=[
@@ -147,7 +147,7 @@ def download_image(ctx, config):
                 tdir=testdir,
                 client=client,
                 )
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.keys()
             remote.run(
                 args=[
                     'rm', '-f', base_file,
@@ -160,7 +160,7 @@ def run_qemu(ctx, config):
     procs = []
     testdir = teuthology.get_testdir(ctx)
     for client, client_config in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         log_dir = '{tdir}/archive/qemu/{client}'.format(tdir=testdir, client=client)
         remote.run(
             args=[
@@ -228,7 +228,7 @@ def run_qemu(ctx, config):
 
         log.debug('checking that qemu tests succeeded...')
         for client in config.iterkeys():
-            remote = teuthology.get_single_remote_value(ctx, client)
+            (remote,) = ctx.cluster.only(client).remotes.keys()
             remote.run(
                 args=[
                     'test', '-f',
diff --git a/teuthology/task/rados.py b/teuthology/task/rados.py
index ffb33b4c1..0897726a6 100644
--- a/teuthology/task/rados.py
+++ b/teuthology/task/rados.py
@@ -120,7 +120,7 @@ def task(ctx, config):
         """Thread spawned by gevent"""
         if not hasattr(ctx, 'manager'):
             first_mon = teuthology.get_first_mon(ctx, config)
-            mon = teuthology.get_single_remote_value(ctx, first_mon)
+            (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
             ctx.manager = CephManager(
                 mon,
                 ctx=ctx,
@@ -147,7 +147,7 @@ def task(ctx, config):
                     pool = ctx.manager.create_pool_with_unique_name(ec_pool=config.get('ec_pool', False))
                     created_pools.append(pool)
 
-                remote = teuthology.get_single_remote_value(ctx, role)
+                (remote,) = ctx.cluster.only(role).remotes.iterkeys()
                 proc = remote.run(
                     args=["CEPH_CLIENT_ID={id_}".format(id_=id_)] + args +
                     ["--pool", pool],
diff --git a/teuthology/task/radosbench.py b/teuthology/task/radosbench.py
index b3e4c8b0f..d2e75716e 100644
--- a/teuthology/task/radosbench.py
+++ b/teuthology/task/radosbench.py
@@ -44,7 +44,7 @@ def task(ctx, config):
         PREFIX = 'client.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
 
         pool = 'data'
         if config.get('pool'):
diff --git a/teuthology/task/radosgw-admin-rest.py b/teuthology/task/radosgw-admin-rest.py
index 1d31f1dc5..43cf73539 100644
--- a/teuthology/task/radosgw-admin-rest.py
+++ b/teuthology/task/radosgw-admin-rest.py
@@ -53,7 +53,7 @@ def rgwadmin(ctx, client, cmd):
         '--format', 'json',
         ]
     pre.extend(cmd)
-    remote = teuthology.get_single_remote_value(ctx, client)
+    (remote,) = ctx.cluster.only(client).remotes.iterkeys()
     proc = remote.run(
         args=pre,
         check_status=False,
@@ -217,7 +217,7 @@ def task(ctx, config):
     logging.error(err)
     assert not err
 
-    remote = teuthology.get_single_remote_value(ctx, client)
+    (remote,) = ctx.cluster.only(client).remotes.iterkeys()
     remote_host = remote.name.split('@')[1]
     admin_conn = boto.s3.connection.S3Connection(
         aws_access_key_id=admin_access_key,
diff --git a/teuthology/task/radosgw-agent.py b/teuthology/task/radosgw-agent.py
index ae0c4f87e..6d48e0df0 100644
--- a/teuthology/task/radosgw-agent.py
+++ b/teuthology/task/radosgw-agent.py
@@ -33,7 +33,7 @@ def run_radosgw_agent(ctx, config):
         log.info("dest is %s", dest_zone)
 
         testdir = teuthology.get_testdir(ctx)
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         # figure out which branch to pull from
         branch = cconf.get('force-branch', None)
         if not branch:
diff --git a/teuthology/task/rbd.py b/teuthology/task/rbd.py
index 16a91f61e..7d07a6115 100644
--- a/teuthology/task/rbd.py
+++ b/teuthology/task/rbd.py
@@ -53,7 +53,7 @@ def create_image(ctx, config):
         name = properties.get('image_name', default_image_name(role))
         size = properties.get('image_size', 10240)
         fmt = properties.get('image_format', 1)
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
         log.info('Creating image {name} with size {size}'.format(name=name,
                                                                  size=size))
         args = [
@@ -79,7 +79,7 @@ def create_image(ctx, config):
             if properties is None:
                 properties = {}
             name = properties.get('image_name', default_image_name(role))
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             remote.run(
                 args=[
                     'adjust-ulimits',
@@ -106,7 +106,7 @@ def modprobe(ctx, config):
     """
     log.info('Loading rbd kernel module...')
     for role in config:
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
         remote.run(
             args=[
                 'sudo',
@@ -119,7 +119,7 @@ def modprobe(ctx, config):
     finally:
         log.info('Unloading rbd kernel module...')
         for role in config:
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             remote.run(
                 args=[
                     'sudo',
@@ -164,7 +164,7 @@ def dev_create(ctx, config):
     for role, image in role_images:
         if image is None:
             image = default_image_name(role)
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
 
         remote.run(
             args=[
@@ -191,7 +191,7 @@ def dev_create(ctx, config):
         for role, image in role_images:
             if image is None:
                 image = default_image_name(role)
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             remote.run(
                 args=[
                     'LD_LIBRARY_PATH={tdir}/binary/usr/local/lib'.format(tdir=testdir),
@@ -287,7 +287,7 @@ def run_xfstests_one_client(ctx, role, properties):
         fs_type = properties.get('fs_type')
         tests = properties.get('tests')
 
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.keys()
 
         # Fetch the test script
         test_root = teuthology.get_testdir(ctx)
diff --git a/teuthology/task/rbd_fsx.py b/teuthology/task/rbd_fsx.py
index 8cb5101fe..6d55b5cf4 100644
--- a/teuthology/task/rbd_fsx.py
+++ b/teuthology/task/rbd_fsx.py
@@ -43,7 +43,7 @@ def task(ctx, config):
 def _run_one_client(ctx, config, role):
     """Spawned task that runs the client"""
     testdir = teuthology.get_testdir(ctx)
-    remote = teuthology.get_single_remote_value(ctx, role)
+    (remote,) = ctx.cluster.only(role).remotes.iterkeys()
     remote.run(
         args=[
             'adjust-ulimits',
diff --git a/teuthology/task/recovery_bench.py b/teuthology/task/recovery_bench.py
index 5c12bdbc9..1984b97d3 100644
--- a/teuthology/task/recovery_bench.py
+++ b/teuthology/task/recovery_bench.py
@@ -48,7 +48,7 @@ def task(ctx, config):
     log.info('Beginning recovery bench...')
 
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
@@ -113,8 +113,7 @@ class RecoveryBencher:
         io_size = self.config.get("io_size", 4096)
 
         osd = str(random.choice(self.osds))
-        osd_remote = teuthology.get_single_remote_value(self.ceph_manager.ctx,
-                'osd.%s' % osd)
+        (osd_remote,) = self.ceph_manager.ctx.cluster.only('osd.%s' % osd).remotes.iterkeys()
 
         testdir = teuthology.get_testdir(self.ceph_manager.ctx)
 
diff --git a/teuthology/task/repair_test.py b/teuthology/task/repair_test.py
index f1063a186..1dd8f2fde 100644
--- a/teuthology/task/repair_test.py
+++ b/teuthology/task/repair_test.py
@@ -98,7 +98,7 @@ def gen_repair_test_2(chooser):
         log.info("starting repair test type 2")
         victim_osd = chooser(pool, 0)
         first_mon = teuthology.get_first_mon(ctx, config)
-        mon = teuthology.get_single_remote_value(ctx, first_mon)
+        (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
         # create object
         log.info("doing put and setomapval")
@@ -191,7 +191,7 @@ def task(ctx, config):
 
     if not hasattr(ctx, 'manager'):
         first_mon = teuthology.get_first_mon(ctx, config)
-        mon = teuthology.get_single_remote_value(ctx, first_mon)
+        (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
         ctx.manager = ceph_manager.CephManager(
             mon,
             ctx=ctx,
diff --git a/teuthology/task/restart.py b/teuthology/task/restart.py
index b508df0f1..87ca2b099 100644
--- a/teuthology/task/restart.py
+++ b/teuthology/task/restart.py
@@ -98,7 +98,7 @@ def task(ctx, config):
         assert 'exec' in config, "config requires exec key with <role>: <command> entries"
         for role, task in config['exec'].iteritems():
             log.info('restart for role {r}'.format(r=role))
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.iterkeys()
             srcdir, restarts = get_tests(ctx, config, role, remote, testdir)
             log.info('Running command on role %s host %s', role, remote.name)
             spec = '{spec}'.format(spec=task[0])
diff --git a/teuthology/task/rgw.py b/teuthology/task/rgw.py
index 18b89279c..674683a63 100644
--- a/teuthology/task/rgw.py
+++ b/teuthology/task/rgw.py
@@ -78,7 +78,7 @@ def ship_config(ctx, config, role_endpoints):
     log.info('Shipping apache config and rgw.fcgi...')
     src = os.path.join(os.path.dirname(__file__), 'apache.conf.template')
     for client, conf in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         system_type = teuthology.get_system_type(remote)
         if not conf:
             conf = {}
@@ -152,7 +152,7 @@ def start_rgw(ctx, config):
     log.info('Starting rgw...')
     testdir = teuthology.get_testdir(ctx)
     for client in config.iterkeys():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.iterkeys()
 
         client_config = config.get(client)
         if client_config is None:
@@ -235,7 +235,7 @@ def start_apache(ctx, config):
     testdir = teuthology.get_testdir(ctx)
     apaches = {}
     for client in config.iterkeys():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         system_type = teuthology.get_system_type(remote)
         if system_type == 'deb':
             apache_name = 'apache2'
@@ -471,7 +471,7 @@ def create_nonregion_pools(ctx, config, regions):
 
     log.info('creating data pools')
     for client in config.keys():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.iterkeys()
         data_pool = '.rgw.buckets'
         if ctx.rgw.ec_data_pool:
             create_ec_pool(remote, data_pool, client, 64)
@@ -516,7 +516,7 @@ def configure_regions_and_zones(ctx, config, regions, role_endpoints):
 
     # clear out the old defaults
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     # removing these objects from .rgw.root and the per-zone root pools
     # may or may not matter
     rados(ctx, mon,
@@ -533,7 +533,7 @@ def configure_regions_and_zones(ctx, config, regions, role_endpoints):
                   cmd=['-p', zone_info['domain_root'],
                        'rm', 'zone_info.default'])
 
-            remote = teuthology.get_single_remote_value(ctx, role)
+            (remote,) = ctx.cluster.only(role).remotes.keys()
             for pool_info in zone_info['placement_pools']:
                 remote.run(args=['ceph', 'osd', 'pool', 'create',
                                  pool_info['val']['index_pool'], '64', '64'])
diff --git a/teuthology/task/s3readwrite.py b/teuthology/task/s3readwrite.py
index 4c29b1314..476015d76 100644
--- a/teuthology/task/s3readwrite.py
+++ b/teuthology/task/s3readwrite.py
@@ -182,7 +182,7 @@ def configure(ctx, config):
         s3tests_conf['s3'].setdefault('port', def_conf['port'])
         s3tests_conf['s3'].setdefault('is_secure', def_conf['is_secure'])
 
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         remote.run(
             args=[
                 'cd',
@@ -216,7 +216,7 @@ def run_tests(ctx, config):
     assert isinstance(config, dict)
     testdir = teuthology.get_testdir(ctx)
     for client, client_config in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         conf = teuthology.get_file(remote, '{tdir}/archive/s3readwrite.{client}.config.yaml'.format(tdir=testdir, client=client))
         args = [
                 '{tdir}/s3-tests/virtualenv/bin/s3tests-test-readwrite'.format(tdir=testdir),
diff --git a/teuthology/task/s3roundtrip.py b/teuthology/task/s3roundtrip.py
index 38b5705d2..5a7093d6f 100644
--- a/teuthology/task/s3roundtrip.py
+++ b/teuthology/task/s3roundtrip.py
@@ -147,7 +147,7 @@ def configure(ctx, config):
         s3tests_conf['s3'].setdefault('port', def_conf['port'])
         s3tests_conf['s3'].setdefault('is_secure', def_conf['is_secure'])
 
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         remote.run(
             args=[
                 'cd',
@@ -181,7 +181,7 @@ def run_tests(ctx, config):
     assert isinstance(config, dict)
     testdir = teuthology.get_testdir(ctx)
     for client, client_config in config.iteritems():
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         conf = teuthology.get_file(remote, '{tdir}/archive/s3roundtrip.{client}.config.yaml'.format(tdir=testdir, client=client))
         args = [
                 '{tdir}/s3-tests/virtualenv/bin/s3tests-test-roundtrip'.format(tdir=testdir),
diff --git a/teuthology/task/s3tests.py b/teuthology/task/s3tests.py
index f2c2b0728..abbacb9bf 100644
--- a/teuthology/task/s3tests.py
+++ b/teuthology/task/s3tests.py
@@ -246,7 +246,7 @@ def configure(ctx, config):
         else:
             s3tests_conf['DEFAULT']['host'] = 'localhost'
 
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         remote.run(
             args=[
                 'cd',
diff --git a/teuthology/task/samba.py b/teuthology/task/samba.py
index 079120cd2..c2e6e6a21 100644
--- a/teuthology/task/samba.py
+++ b/teuthology/task/samba.py
@@ -23,7 +23,7 @@ def get_sambas(ctx, roles):
         PREFIX = 'samba.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         yield (id_, remote)
 
 @contextlib.contextmanager
diff --git a/teuthology/task/scrub.py b/teuthology/task/scrub.py
index e7285dfe7..7a25300a6 100644
--- a/teuthology/task/scrub.py
+++ b/teuthology/task/scrub.py
@@ -39,7 +39,7 @@ def task(ctx, config):
     log.info('Beginning scrub...')
 
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
 
     manager = ceph_manager.CephManager(
         mon,
diff --git a/teuthology/task/scrub_test.py b/teuthology/task/scrub_test.py
index f5249666b..3443ae9f4 100644
--- a/teuthology/task/scrub_test.py
+++ b/teuthology/task/scrub_test.py
@@ -33,7 +33,7 @@ def task(ctx, config):
     assert isinstance(config, dict), \
         'scrub_test task only accepts a dict for configuration'
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     
     num_osds = teuthology.num_instances_of_type(ctx.cluster, 'osd')
     log.info('num_osds is %s' % num_osds)
@@ -73,7 +73,7 @@ def task(ctx, config):
 
     log.info('messing with PG %s on osd %d' % (victim, osd))
 
-    osd_remote = teuthology.get_single_remote_value(ctx, 'osd.%d' % osd)
+    (osd_remote,) = ctx.cluster.only('osd.%d' % osd).remotes.iterkeys()
     data_path = os.path.join(
         '/var/lib/ceph/osd',
         'ceph-{id}'.format(id=osd),
diff --git a/teuthology/task/swift.py b/teuthology/task/swift.py
index efc858776..6285eb6b1 100644
--- a/teuthology/task/swift.py
+++ b/teuthology/task/swift.py
@@ -133,7 +133,7 @@ def configure(ctx, config):
             testswift_conf['func_test']['auth_host'] = 'localhost'
 
         log.info(client)
-        remote = teuthology.get_single_remote_value(ctx, client)
+        (remote,) = ctx.cluster.only(client).remotes.keys()
         remote.run(
             args=[
                 'cd',
diff --git a/teuthology/task/thrashosds.py b/teuthology/task/thrashosds.py
index 37ac03765..c5f26dcb7 100644
--- a/teuthology/task/thrashosds.py
+++ b/teuthology/task/thrashosds.py
@@ -152,7 +152,7 @@ def task(ctx, config):
 
     log.info('Beginning thrashosds...')
     first_mon = teuthology.get_first_mon(ctx, config)
-    mon = teuthology.get_single_remote_value(ctx, first_mon)
+    (mon,) = ctx.cluster.only(first_mon).remotes.iterkeys()
     manager = ceph_manager.CephManager(
         mon,
         ctx=ctx,
diff --git a/teuthology/task/watch_notify_stress.py b/teuthology/task/watch_notify_stress.py
index 2402840e0..ab611c3dd 100644
--- a/teuthology/task/watch_notify_stress.py
+++ b/teuthology/task/watch_notify_stress.py
@@ -6,7 +6,6 @@ import logging
 import proc_thrasher
 
 from ..orchestra import run
-from teuthology import misc as teuthology
 
 log = logging.getLogger(__name__)
 
@@ -41,7 +40,7 @@ def task(ctx, config):
         PREFIX = 'client.'
         assert role.startswith(PREFIX)
         id_ = role[len(PREFIX):]
-        remote = teuthology.get_single_remote_value(ctx, role)
+        (remote,) = ctx.cluster.only(role).remotes.iterkeys()
         remotes.append(remote)
 
         args =['CEPH_CLIENT_ID={id_}'.format(id_=id_),
diff --git a/teuthology/task/workunit.py b/teuthology/task/workunit.py
index 412d800e5..b504eeb50 100644
--- a/teuthology/task/workunit.py
+++ b/teuthology/task/workunit.py
@@ -127,7 +127,7 @@ def _delete_dir(ctx, role):
     PREFIX = 'client.'
     testdir = teuthology.get_testdir(ctx)
     id_ = role[len(PREFIX):]
-    remote = teuthology.get_single_remote_value(ctx, role)
+    (remote,) = ctx.cluster.only(role).remotes.iterkeys()
     mnt = os.path.join(testdir, 'mnt.{id}'.format(id=id_))
     # Is there any reason why this is not: join(mnt, role) ?
     client = os.path.join(mnt, 'client.{id}'.format(id=id_))
@@ -169,7 +169,7 @@ def _make_scratch_dir(ctx, role, subdir):
     PREFIX = 'client.'
     id_ = role[len(PREFIX):]
     log.debug("getting remote for {id} role {role_}".format(id=id_, role_=role))
-    remote = teuthology.get_single_remote_value(ctx, role)
+    (remote,) = ctx.cluster.only(role).remotes.iterkeys()
     dir_owner = remote.shortname.split('@', 1)[0]
     mnt = os.path.join(teuthology.get_testdir(ctx), 'mnt.{id}'.format(id=id_))
     # if neither kclient nor ceph-fuse are required for a workunit,
@@ -240,8 +240,7 @@ def _spawn_on_all_clients(ctx, refspec, tests, env, subdir, timeout=None):
     client_generator = teuthology.all_roles_of_type(ctx.cluster, 'client')
     client_remotes = list()
     for client in client_generator:
-        client_remote = teuthology.get_single_remote_value(ctx, 
-                'client.{id}'.format(id=client))
+        (client_remote,) = ctx.cluster.only('client.{id}'.format(id=client)).remotes.iterkeys()
         client_remotes.append((client_remote, 'client.{id}'.format(id=client)))
         _make_scratch_dir(ctx, "client.{id}".format(id=client), subdir)
 
@@ -280,7 +279,7 @@ def _run_tests(ctx, refspec, role, tests, env, subdir=None, timeout=None):
     PREFIX = 'client.'
     assert role.startswith(PREFIX)
     id_ = role[len(PREFIX):]
-    remote = teuthology.get_single_remote_value(ctx, role)
+    (remote,) = ctx.cluster.only(role).remotes.iterkeys()
     mnt = os.path.join(testdir, 'mnt.{id}'.format(id=id_))
     # subdir so we can remove and recreate this a lot without sudo
     if subdir is None:
diff --git a/teuthology/task_util/rgw.py b/teuthology/task_util/rgw.py
index 7650c4cdf..cbe3071fb 100644
--- a/teuthology/task_util/rgw.py
+++ b/teuthology/task_util/rgw.py
@@ -29,7 +29,7 @@ def rgwadmin(ctx, client, cmd, stdin=StringIO(), check_status=False):
         ]
     pre.extend(cmd)
     log.info('rgwadmin: cmd=%s' % pre)
-    remote = teuthology.get_single_remote_value(ctx, client)
+    (remote,) = ctx.cluster.only(client).remotes.iterkeys()
     proc = remote.run(
         args=pre,
         check_status=check_status,