SmartOS: Add support for Joyent LX-Brand Zones (LP: #1540965)

LX-brand zones on Joyent's SmartOS use a different metadata source
(socket file) than the KVM-based SmartOS virtualization (serial port).
This patch adds support for recognizing the different flavors of
virtualization on SmartOS and setting up a metadata source file object.
After the file object is created, the rest of the code for the datasource

LP: #1540965

3 files changed, 216 insertions, 133 deletions

diff --git a/cloudinit/sources/DataSourceSmartOS.py b/cloudinit/sources/DataSourceSmartOS.py
index c9b497df..7453379a 100644
--- a/cloudinit/sources/DataSourceSmartOS.py
+++ b/cloudinit/sources/DataSourceSmartOS.py
@@ -20,10 +20,13 @@
 #    Datasource for provisioning on SmartOS. This works on Joyent
 #        and public/private Clouds using SmartOS.
 #
-#    SmartOS hosts use a serial console (/dev/ttyS1) on Linux Guests.
+#    SmartOS hosts use a serial console (/dev/ttyS1) on KVM Linux Guests
 #        The meta-data is transmitted via key/value pairs made by
 #        requests on the console. For example, to get the hostname, you
 #        would send "GET hostname" on /dev/ttyS1.
+#        For Linux Guests running in LX-Brand Zones on SmartOS hosts
+#        a socket (/native/.zonecontrol/metadata.sock) is used instead
+#        of a serial console.
 #
 #   Certain behavior is defined by the DataDictionary
 #       http://us-east.manta.joyent.com/jmc/public/mdata/datadict.html
@@ -34,6 +37,8 @@ import contextlib
 import os
 import random
 import re
+import socket
+import stat
 
 import serial
 
@@ -46,6 +51,7 @@ LOG = logging.getLogger(__name__)
 
 SMARTOS_ATTRIB_MAP = {
     # Cloud-init Key : (SmartOS Key, Strip line endings)
+    'instance-id': ('sdc:uuid', True),
     'local-hostname': ('hostname', True),
     'public-keys': ('root_authorized_keys', True),
     'user-script': ('user-script', False),
@@ -76,6 +82,7 @@ DS_CFG_PATH = ['datasource', DS_NAME]
 #
 BUILTIN_DS_CONFIG = {
     'serial_device': '/dev/ttyS1',
+    'metadata_sockfile': '/native/.zonecontrol/metadata.sock',
     'seed_timeout': 60,
     'no_base64_decode': ['root_authorized_keys',
                          'motd_sys_info',
@@ -83,6 +90,7 @@ BUILTIN_DS_CONFIG = {
                          'user-data',
                          'user-script',
                          'sdc:datacenter_name',
+                         'sdc:uuid',
                         ],
     'base64_keys': [],
     'base64_all': False,
@@ -150,17 +158,27 @@ class DataSourceSmartOS(sources.DataSource):
     def __init__(self, sys_cfg, distro, paths):
         sources.DataSource.__init__(self, sys_cfg, distro, paths)
         self.is_smartdc = None
-
         self.ds_cfg = util.mergemanydict([
             self.ds_cfg,
             util.get_cfg_by_path(sys_cfg, DS_CFG_PATH, {}),
             BUILTIN_DS_CONFIG])
 
         self.metadata = {}
-        self.cfg = BUILTIN_CLOUD_CONFIG
 
-        self.seed = self.ds_cfg.get("serial_device")
-        self.seed_timeout = self.ds_cfg.get("serial_timeout")
+        # SDC LX-Brand Zones lack dmidecode (no /dev/mem) but
+        # report 'BrandZ virtual linux' as the kernel version
+        if os.uname()[3].lower() == 'brandz virtual linux':
+            LOG.debug("Host is SmartOS, guest in Zone")
+            self.is_smartdc = True
+            self.smartos_type = 'lx-brand'
+            self.cfg = {}
+            self.seed = self.ds_cfg.get("metadata_sockfile")
+        else:
+            self.is_smartdc = True
+            self.smartos_type = 'kvm'
+            self.seed = self.ds_cfg.get("serial_device")
+            self.cfg = BUILTIN_CLOUD_CONFIG
+            self.seed_timeout = self.ds_cfg.get("serial_timeout")
         self.smartos_no_base64 = self.ds_cfg.get('no_base64_decode')
         self.b64_keys = self.ds_cfg.get('base64_keys')
         self.b64_all = self.ds_cfg.get('base64_all')
@@ -170,12 +188,49 @@ class DataSourceSmartOS(sources.DataSource):
         root = sources.DataSource.__str__(self)
         return "%s [seed=%s]" % (root, self.seed)
 
+    def _get_seed_file_object(self):
+        if not self.seed:
+            raise AttributeError("seed device is not set")
+
+        if self.smartos_type == 'lx-brand':
+            if not stat.S_ISSOCK(os.stat(self.seed).st_mode):
+                LOG.debug("Seed %s is not a socket", self.seed)
+                return None
+            sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+            sock.connect(self.seed)
+            return sock.makefile('rwb')
+        else:
+            if not stat.S_ISCHR(os.stat(self.seed).st_mode):
+                LOG.debug("Seed %s is not a character device")
+                return None
+            ser = serial.Serial(self.seed, timeout=self.seed_timeout)
+            if not ser.isOpen():
+                raise SystemError("Unable to open %s" % self.seed)
+            return ser
+        return None
+
+    def _set_provisioned(self):
+        '''Mark the instance provisioning state as successful.
+
+        When run in a zone, the host OS will look for /var/svc/provisioning
+        to be renamed as /var/svc/provision_success.   This should be done
+        after meta-data is successfully retrieved and from this point
+        the host considers the provision of the zone to be a success and
+        keeps the zone running.
+        '''
+
+        LOG.debug('Instance provisioning state set as successful')
+        svc_path = '/var/svc'
+        if os.path.exists('/'.join([svc_path, 'provisioning'])):
+            os.rename('/'.join([svc_path, 'provisioning']),
+                      '/'.join([svc_path, 'provision_success']))
+
     def get_data(self):
         md = {}
         ud = ""
 
         if not device_exists(self.seed):
-            LOG.debug("No serial device '%s' found for SmartOS datasource",
+            LOG.debug("No metadata device '%s' found for SmartOS datasource",
                       self.seed)
             return False
 
@@ -185,29 +240,36 @@ class DataSourceSmartOS(sources.DataSource):
             LOG.debug("Disabling SmartOS datasource on arm (LP: #1243287)")
             return False
 
-        dmi_info = dmi_data()
-        if dmi_info is False:
-            LOG.debug("No dmidata utility found")
-            return False
-
-        system_uuid, system_type = tuple(dmi_info)
-        if 'smartdc' not in system_type.lower():
-            LOG.debug("Host is not on SmartOS. system_type=%s", system_type)
+        # SDC KVM instances will provide dmi data, LX-brand does not
+        if self.smartos_type == 'kvm':
+            dmi_info = dmi_data()
+            if dmi_info is False:
+                LOG.debug("No dmidata utility found")
+                return False
+
+            system_type = dmi_info
+            if 'smartdc' not in system_type.lower():
+                LOG.debug("Host is not on SmartOS. system_type=%s",
+                          system_type)
+                return False
+            LOG.debug("Host is SmartOS, guest in KVM")
+
+        seed_obj = self._get_seed_file_object()
+        if seed_obj is None:
+            LOG.debug('Seed file object not found.')
             return False
-        self.is_smartdc = True
-        md['instance-id'] = system_uuid
+        with contextlib.closing(seed_obj) as seed:
+            b64_keys = self.query('base64_keys', seed, strip=True, b64=False)
+            if b64_keys is not None:
+                self.b64_keys = [k.strip() for k in str(b64_keys).split(',')]
 
-        b64_keys = self.query('base64_keys', strip=True, b64=False)
-        if b64_keys is not None:
-            self.b64_keys = [k.strip() for k in str(b64_keys).split(',')]
+            b64_all = self.query('base64_all', seed, strip=True, b64=False)
+            if b64_all is not None:
+                self.b64_all = util.is_true(b64_all)
 
-        b64_all = self.query('base64_all', strip=True, b64=False)
-        if b64_all is not None:
-            self.b64_all = util.is_true(b64_all)
-
-        for ci_noun, attribute in SMARTOS_ATTRIB_MAP.items():
-            smartos_noun, strip = attribute
-            md[ci_noun] = self.query(smartos_noun, strip=strip)
+            for ci_noun, attribute in SMARTOS_ATTRIB_MAP.items():
+                smartos_noun, strip = attribute
+                md[ci_noun] = self.query(smartos_noun, seed, strip=strip)
 
         # @datadictionary: This key may contain a program that is written
         # to a file in the filesystem of the guest on each boot and then
@@ -240,7 +302,7 @@ class DataSourceSmartOS(sources.DataSource):
 
         # Handle the cloud-init regular meta
         if not md['local-hostname']:
-            md['local-hostname'] = system_uuid
+            md['local-hostname'] = md['instance-id']
 
         ud = None
         if md['user-data']:
@@ -257,6 +319,8 @@ class DataSourceSmartOS(sources.DataSource):
         self.metadata = util.mergemanydict([md, self.metadata])
         self.userdata_raw = ud
         self.vendordata_raw = md['vendor-data']
+
+        self._set_provisioned()
         return True
 
     def device_name_to_device(self, name):
@@ -268,40 +332,64 @@ class DataSourceSmartOS(sources.DataSource):
     def get_instance_id(self):
         return self.metadata['instance-id']
 
-    def query(self, noun, strip=False, default=None, b64=None):
+    def query(self, noun, seed_file, strip=False, default=None, b64=None):
         if b64 is None:
             if noun in self.smartos_no_base64:
                 b64 = False
             elif self.b64_all or noun in self.b64_keys:
                 b64 = True
 
-        return query_data(noun=noun, strip=strip, seed_device=self.seed,
-                          seed_timeout=self.seed_timeout, default=default,
-                          b64=b64)
+        return self._query_data(noun, seed_file, strip=strip,
+                                default=default, b64=b64)
 
+    def _query_data(self, noun, seed_file, strip=False,
+                    default=None, b64=None):
+        """Makes a request via "GET <NOUN>"
 
-def device_exists(device):
-    """Symplistic method to determine if the device exists or not"""
-    return os.path.exists(device)
+           In the response, the first line is the status, while subsequent
+           lines are is the value. A blank line with a "." is used to
+           indicate end of response.
 
+           If the response is expected to be base64 encoded, then set
+           b64encoded to true. Unfortantely, there is no way to know if
+           something is 100% encoded, so this method relies on being told
+           if the data is base64 or not.
+        """
 
-def get_serial(seed_device, seed_timeout):
-    """This is replaced in unit testing, allowing us to replace
-        serial.Serial with a mocked class.
+        if not noun:
+            return False
 
-        The timeout value of 60 seconds should never be hit. The value
-        is taken from SmartOS own provisioning tools. Since we are reading
-        each line individually up until the single ".", the transfer is
-        usually very fast (i.e. microseconds) to get the response.
-    """
-    if not seed_device:
-        raise AttributeError("seed_device value is not set")
+        response = JoyentMetadataClient(seed_file).get_metadata(noun)
+
+        if response is None:
+            return default
+
+        if b64 is None:
+            b64 = self._query_data('b64-%s' % noun, seed_file, b64=False,
+                                   default=False, strip=True)
+            b64 = util.is_true(b64)
+
+        resp = None
+        if b64 or strip:
+            resp = "".join(response).rstrip()
+        else:
+            resp = "".join(response)
 
-    ser = serial.Serial(seed_device, timeout=seed_timeout)
-    if not ser.isOpen():
-        raise SystemError("Unable to open %s" % seed_device)
+        if b64:
+            try:
+                return util.b64d(resp)
+            # Bogus input produces different errors in Python 2 and 3;
+            # catch both.
+            except (TypeError, binascii.Error):
+                LOG.warn("Failed base64 decoding key '%s'", noun)
+                return resp
 
-    return ser
+        return resp
+
+
+def device_exists(device):
+    """Symplistic method to determine if the device exists or not"""
+    return os.path.exists(device)
 
 
 class JoyentMetadataFetchException(Exception):
@@ -320,8 +408,8 @@ class JoyentMetadataClient(object):
         r' (?P<body>(?P<request_id>[0-9a-f]+) (?P<status>SUCCESS|NOTFOUND)'
         r'( (?P<payload>.+))?)')
 
-    def __init__(self, serial):
-        self.serial = serial
+    def __init__(self, metasource):
+        self.metasource = metasource
 
     def _checksum(self, body):
         return '{0:08x}'.format(
@@ -356,67 +444,30 @@ class JoyentMetadataClient(object):
                                             util.b64e(metadata_key))
         msg = 'V2 {0} {1} {2}\n'.format(
             len(message_body), self._checksum(message_body), message_body)
-        LOG.debug('Writing "%s" to serial port.', msg)
-        self.serial.write(msg.encode('ascii'))
-        response = self.serial.readline().decode('ascii')
-        LOG.debug('Read "%s" from serial port.', response)
-        return self._get_value_from_frame(request_id, response)
-
-
-def query_data(noun, seed_device, seed_timeout, strip=False, default=None,
-               b64=None):
-    """Makes a request to via the serial console via "GET <NOUN>"
-
-        In the response, the first line is the status, while subsequent lines
-        are is the value. A blank line with a "." is used to indicate end of
-        response.
-
-        If the response is expected to be base64 encoded, then set b64encoded
-        to true. Unfortantely, there is no way to know if something is 100%
-        encoded, so this method relies on being told if the data is base64 or
-        not.
-    """
-    if not noun:
-        return False
-
-    with contextlib.closing(get_serial(seed_device, seed_timeout)) as ser:
-        client = JoyentMetadataClient(ser)
-        response = client.get_metadata(noun)
-
-    if response is None:
-        return default
-
-    if b64 is None:
-        b64 = query_data('b64-%s' % noun, seed_device=seed_device,
-                         seed_timeout=seed_timeout, b64=False,
-                         default=False, strip=True)
-        b64 = util.is_true(b64)
-
-    resp = None
-    if b64 or strip:
-        resp = "".join(response).rstrip()
-    else:
-        resp = "".join(response)
-
-    if b64:
-        try:
-            return util.b64d(resp)
-        # Bogus input produces different errors in Python 2 and 3; catch both.
-        except (TypeError, binascii.Error):
-            LOG.warn("Failed base64 decoding key '%s'", noun)
-            return resp
+        LOG.debug('Writing "%s" to metadata transport.', msg)
+        self.metasource.write(msg.encode('ascii'))
+        self.metasource.flush()
+
+        response = bytearray()
+        response.extend(self.metasource.read(1))
+        while response[-1:] !=  b'\n':
+            response.extend(self.metasource.read(1))
+        response = response.rstrip().decode('ascii')
+        LOG.debug('Read "%s" from metadata transport.', response)
+
+        if 'SUCCESS' not in response:
+            return None
 
-    return resp
+        return self._get_value_from_frame(request_id, response)
 
 
 def dmi_data():
-    sys_uuid = util.read_dmi_data("system-uuid")
     sys_type = util.read_dmi_data("system-product-name")
 
-    if not sys_uuid or not sys_type:
+    if not sys_type:
         return None
 
-    return (sys_uuid.lower(), sys_type)
+    return sys_type
 
 
 def write_boot_content(content, content_f, link=None, shebang=False,
diff --git a/doc/examples/cloud-config-datasources.txt b/doc/examples/cloud-config-datasources.txt
index 3bde4aac..2651c027 100644
--- a/doc/examples/cloud-config-datasources.txt
+++ b/doc/examples/cloud-config-datasources.txt
@@ -51,12 +51,19 @@ datasource:
       policy: on # [can be 'on', 'off' or 'force']
 
   SmartOS:
+    # For KVM guests:
     # Smart OS datasource works over a serial console interacting with
     # a server on the other end. By default, the second serial console is the
     # device. SmartOS also uses a serial timeout of 60 seconds.
     serial_device: /dev/ttyS1
     serial_timeout: 60
 
+    # For LX-Brand Zones guests:
+    # Smart OS datasource works over a socket interacting with
+    # the host on the other end. By default, the socket file is in
+    # the native .zoncontrol directory.
+    metadata_sockfile: /native/.zonecontrol/metadata.sock
+
     # a list of keys that will not be base64 decoded even if base64_all
     no_base64_decode: ['root_authorized_keys', 'motd_sys_info',
                        'iptables_disable']
diff --git a/tests/unittests/test_datasource/test_smartos.py b/tests/unittests/test_datasource/test_smartos.py
index adee9019..1235436d 100644
--- a/tests/unittests/test_datasource/test_smartos.py
+++ b/tests/unittests/test_datasource/test_smartos.py
@@ -31,6 +31,7 @@ import shutil
 import stat
 import tempfile
 import uuid
+import unittest
 from binascii import crc32
 
 import serial
@@ -56,12 +57,13 @@ MOCK_RETURNS = {
     'cloud-init:user-data': '\n'.join(['#!/bin/sh', '/bin/true', '']),
     'sdc:datacenter_name': 'somewhere2',
     'sdc:operator-script': '\n'.join(['bin/true', '']),
+    'sdc:uuid': str(uuid.uuid4()),
     'sdc:vendor-data': '\n'.join(['VENDOR_DATA', '']),
     'user-data': '\n'.join(['something', '']),
     'user-script': '\n'.join(['/bin/true', '']),
 }
 
-DMI_DATA_RETURN = (str(uuid.uuid4()), 'smartdc')
+DMI_DATA_RETURN = 'smartdc'
 
 
 def get_mock_client(mockdata):
@@ -111,7 +113,8 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
         ret = apply_patches(patches)
         self.unapply += ret
 
-    def _get_ds(self, sys_cfg=None, ds_cfg=None, mockdata=None, dmi_data=None):
+    def _get_ds(self, sys_cfg=None, ds_cfg=None, mockdata=None, dmi_data=None,
+                is_lxbrand=False):
         mod = DataSourceSmartOS
 
         if mockdata is None:
@@ -124,9 +127,13 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
             return dmi_data
 
         def _os_uname():
-            # LP: #1243287. tests assume this runs, but running test on
-            # arm would cause them all to fail.
-            return ('LINUX', 'NODENAME', 'RELEASE', 'VERSION', 'x86_64')
+            if not is_lxbrand:
+                # LP: #1243287. tests assume this runs, but running test on
+                # arm would cause them all to fail.
+                return ('LINUX', 'NODENAME', 'RELEASE', 'VERSION', 'x86_64')
+            else:
+                return ('LINUX', 'NODENAME', 'RELEASE', 'BRANDZ VIRTUAL LINUX',
+                        'X86_64')
 
         if sys_cfg is None:
             sys_cfg = {}
@@ -136,7 +143,6 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
             sys_cfg['datasource']['SmartOS'] = ds_cfg
 
         self.apply_patches([(mod, 'LEGACY_USER_D', self.legacy_user_d)])
-        self.apply_patches([(mod, 'get_serial', mock.MagicMock())])
         self.apply_patches([
             (mod, 'JoyentMetadataClient', get_mock_client(mockdata))])
         self.apply_patches([(mod, 'dmi_data', _dmi_data)])
@@ -144,6 +150,7 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
         self.apply_patches([(mod, 'device_exists', lambda d: True)])
         dsrc = mod.DataSourceSmartOS(sys_cfg, distro=None,
                                      paths=self.paths)
+        self.apply_patches([(dsrc, '_get_seed_file_object', mock.MagicMock())])
         return dsrc
 
     def test_seed(self):
@@ -151,14 +158,29 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
         dsrc = self._get_ds()
         ret = dsrc.get_data()
         self.assertTrue(ret)
+        self.assertEquals('kvm', dsrc.smartos_type)
         self.assertEquals('/dev/ttyS1', dsrc.seed)
 
+    def test_seed_lxbrand(self):
+        # default seed should be /dev/ttyS1
+        dsrc = self._get_ds(is_lxbrand=True)
+        ret = dsrc.get_data()
+        self.assertTrue(ret)
+        self.assertEquals('lx-brand', dsrc.smartos_type)
+        self.assertEquals('/native/.zonecontrol/metadata.sock', dsrc.seed)
+
     def test_issmartdc(self):
         dsrc = self._get_ds()
         ret = dsrc.get_data()
         self.assertTrue(ret)
         self.assertTrue(dsrc.is_smartdc)
 
+    def test_issmartdc_lxbrand(self):
+        dsrc = self._get_ds(is_lxbrand=True)
+        ret = dsrc.get_data()
+        self.assertTrue(ret)
+        self.assertTrue(dsrc.is_smartdc)
+
     def test_no_base64(self):
         ds_cfg = {'no_base64_decode': ['test_var1'], 'all_base': True}
         dsrc = self._get_ds(ds_cfg=ds_cfg)
@@ -169,7 +191,8 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
         dsrc = self._get_ds(mockdata=MOCK_RETURNS)
         ret = dsrc.get_data()
         self.assertTrue(ret)
-        self.assertEquals(DMI_DATA_RETURN[0], dsrc.metadata['instance-id'])
+        self.assertEquals(MOCK_RETURNS['sdc:uuid'],
+                          dsrc.metadata['instance-id'])
 
     def test_root_keys(self):
         dsrc = self._get_ds(mockdata=MOCK_RETURNS)
@@ -407,18 +430,6 @@ class TestSmartOSDataSource(helpers.FilesystemMockingTestCase):
         self.assertEqual(dsrc.device_name_to_device('FOO'),
                          mydscfg['disk_aliases']['FOO'])
 
-    @mock.patch('cloudinit.sources.DataSourceSmartOS.JoyentMetadataClient')
-    @mock.patch('cloudinit.sources.DataSourceSmartOS.get_serial')
-    def test_serial_console_closed_on_error(self, get_serial, metadata_client):
-        class OurException(Exception):
-            pass
-        metadata_client.side_effect = OurException
-        try:
-            DataSourceSmartOS.query_data('noun', 'device', 0)
-        except OurException:
-            pass
-        self.assertEqual(1, get_serial.return_value.close.call_count)
-
 
 def apply_patches(patches):
     ret = []
@@ -447,14 +458,25 @@ class TestJoyentMetadataClient(helpers.FilesystemMockingTestCase):
         }
 
         def make_response():
-            payload = ''
-            if self.response_parts['payload']:
-                payload = ' {0}'.format(self.response_parts['payload'])
-            del self.response_parts['payload']
-            return (
-                'V2 {length} {crc} {request_id} {command}{payload}\n'.format(
-                    payload=payload, **self.response_parts).encode('ascii'))
-        self.serial.readline.side_effect = make_response
+            payloadstr = ''
+            if 'payload' in self.response_parts:
+                payloadstr = ' {0}'.format(self.response_parts['payload'])
+            return ('V2 {length} {crc} {request_id} '
+                    '{command}{payloadstr}\n'.format(
+                    payloadstr=payloadstr,
+                    **self.response_parts).encode('ascii'))
+
+        self.metasource_data = None
+
+        def read_response(length):
+            if not self.metasource_data:
+                self.metasource_data = make_response()
+                self.metasource_data_len = len(self.metasource_data)
+            resp = self.metasource_data[:length]
+            self.metasource_data = self.metasource_data[length:]
+            return resp
+
+        self.serial.read.side_effect = read_response
         self.patched_funcs.enter_context(
             mock.patch('cloudinit.sources.DataSourceSmartOS.random.randint',
                        mock.Mock(return_value=self.request_id)))
@@ -477,7 +499,9 @@ class TestJoyentMetadataClient(helpers.FilesystemMockingTestCase):
         client.get_metadata('some_key')
         self.assertEqual(1, self.serial.write.call_count)
         written_line = self.serial.write.call_args[0][0]
-        self.assertEndsWith(written_line, b'\n')
+        print(type(written_line))
+        self.assertEndsWith(written_line.decode('ascii'),
+            b'\n'.decode('ascii'))
         self.assertEqual(1, written_line.count(b'\n'))
 
     def _get_written_line(self, key='some_key'):
@@ -489,7 +513,8 @@ class TestJoyentMetadataClient(helpers.FilesystemMockingTestCase):
         self.assertIsInstance(self._get_written_line(), six.binary_type)
 
     def test_get_metadata_line_starts_with_v2(self):
-        self.assertStartsWith(self._get_written_line(), b'V2')
+        foo = self._get_written_line()
+        self.assertStartsWith(foo.decode('ascii'), b'V2'.decode('ascii'))
 
     def test_get_metadata_uses_get_command(self):
         parts = self._get_written_line().decode('ascii').strip().split(' ')
@@ -526,7 +551,7 @@ class TestJoyentMetadataClient(helpers.FilesystemMockingTestCase):
     def test_get_metadata_reads_a_line(self):
         client = self._get_client()
         client.get_metadata('some_key')
-        self.assertEqual(1, self.serial.readline.call_count)
+        self.assertEqual(self.metasource_data_len, self.serial.read.call_count)
 
     def test_get_metadata_returns_valid_value(self):
         client = self._get_client()