openstack: avoid unneeded metadata probe on non-openstack platforms

OpenStack datasource is now discovered in init-local stage. In order to
probe whether OpenStack metadata is present, it performs a costly
sandboxed dhclient setup and metadata probe against http://169.254.169.254
for openstack data.

Cloud-init properly detects non-OpenStack on EC2, but it spends precious
time probing the metadata service also resulting in a confusing WARNING
log about 'metadata not present'. To avoid the wasted cycles, and
confusing warning, get_data will call a detect_openstack function to
quickly determine whether the platform looks like OpenStack before trying
to setup network to probe and crawl the metadata service.

LP: #1776701

5 files changed, 182 insertions, 16 deletions

diff --git a/cloudinit/sources/DataSourceOpenStack.py b/cloudinit/sources/DataSourceOpenStack.py
index 1a12a3f1..365af96a 100644
--- a/cloudinit/sources/DataSourceOpenStack.py
+++ b/cloudinit/sources/DataSourceOpenStack.py
@@ -23,6 +23,13 @@ DEFAULT_METADATA = {
     "instance-id": DEFAULT_IID,
 }
 
+# OpenStack DMI constants
+DMI_PRODUCT_NOVA = 'OpenStack Nova'
+DMI_PRODUCT_COMPUTE = 'OpenStack Compute'
+VALID_DMI_PRODUCT_NAMES = [DMI_PRODUCT_NOVA, DMI_PRODUCT_COMPUTE]
+DMI_ASSET_TAG_OPENTELEKOM = 'OpenTelekomCloud'
+VALID_DMI_ASSET_TAGS = [DMI_ASSET_TAG_OPENTELEKOM]
+
 
 class DataSourceOpenStack(openstack.SourceMixin, sources.DataSource):
 
@@ -114,6 +121,8 @@ class DataSourceOpenStack(openstack.SourceMixin, sources.DataSource):
             False when unable to contact metadata service or when metadata
             format is invalid or disabled.
         """
+        if not detect_openstack():
+            return False
         if self.perform_dhcp_setup:  # Setup networking in init-local stage.
             try:
                 with EphemeralDHCPv4(self.fallback_interface):
@@ -205,6 +214,20 @@ def read_metadata_service(base_url, ssl_details=None,
     return reader.read_v2()
 
 
+def detect_openstack():
+    """Return True when a potential OpenStack platform is detected."""
+    if not util.is_x86():
+        return True  # Non-Intel cpus don't properly report dmi product names
+    product_name = util.read_dmi_data('system-product-name')
+    if product_name in VALID_DMI_PRODUCT_NAMES:
+        return True
+    elif util.read_dmi_data('chassis-asset-tag') in VALID_DMI_ASSET_TAGS:
+        return True
+    elif util.get_proc_env(1).get('product_name') == DMI_PRODUCT_NOVA:
+        return True
+    return False
+
+
 # Used to match classes to dependencies
 datasources = [
     (DataSourceOpenStackLocal, (sources.DEP_FILESYSTEM,)),
diff --git a/cloudinit/util.py b/cloudinit/util.py
index 26a41122..6da95113 100644
--- a/cloudinit/util.py
+++ b/cloudinit/util.py
@@ -2629,6 +2629,16 @@ def _call_dmidecode(key, dmidecode_path):
         return None
 
 
+def is_x86(uname_arch=None):
+    """Return True if platform is x86-based"""
+    if uname_arch is None:
+        uname_arch = os.uname()[4]
+    x86_arch_match = (
+        uname_arch == 'x86_64' or
+        (uname_arch[0] == 'i' and uname_arch[2:] == '86'))
+    return x86_arch_match
+
+
 def read_dmi_data(key):
     """
     Wrapper for reading DMI data.
@@ -2656,8 +2666,7 @@ def read_dmi_data(key):
 
     # running dmidecode can be problematic on some arches (LP: #1243287)
     uname_arch = os.uname()[4]
-    if not (uname_arch == "x86_64" or
-            (uname_arch.startswith("i") and uname_arch[2:] == "86") or
+    if not (is_x86(uname_arch) or
             uname_arch == 'aarch64' or
             uname_arch == 'amd64'):
         LOG.debug("dmidata is not supported on %s", uname_arch)
diff --git a/doc/rtd/topics/datasources/openstack.rst b/doc/rtd/topics/datasources/openstack.rst
index 0ea89943..421da08f 100644
--- a/doc/rtd/topics/datasources/openstack.rst
+++ b/doc/rtd/topics/datasources/openstack.rst
@@ -7,6 +7,21 @@ This datasource supports reading data from the
 `OpenStack Metadata Service
 <https://docs.openstack.org/nova/latest/admin/networking-nova.html#metadata-service>`_.
 
+Discovery
+-------------
+To determine whether a platform looks like it may be OpenStack, cloud-init
+checks the following environment attributes as a potential OpenStack platform:
+
+ * Maybe OpenStack if
+
+   * **non-x86 cpu architecture**: because DMI data is buggy on some arches
+ * Is OpenStack **if x86 architecture and ANY** of the following
+
+   * **/proc/1/environ**: Nova-lxd contains *product_name=OpenStack Nova*
+   * **DMI product_name**: Either *Openstack Nova* or *OpenStack Compute*
+   * **DMI chassis_asset_tag** is *OpenTelekomCloud*
+
+
 Configuration
 -------------
 The following configuration can be set for the datasource in system
diff --git a/tests/unittests/test_datasource/test_openstack.py b/tests/unittests/test_datasource/test_openstack.py
index fad73b21..585acc33 100644
--- a/tests/unittests/test_datasource/test_openstack.py
+++ b/tests/unittests/test_datasource/test_openstack.py
@@ -69,6 +69,8 @@ EC2_VERSIONS = [
     'latest',
 ]
 
+MOCK_PATH = 'cloudinit.sources.DataSourceOpenStack.'
+
 
 # TODO _register_uris should leverage test_ec2.register_mock_metaserver.
 def _register_uris(version, ec2_files, ec2_meta, os_files):
@@ -231,7 +233,10 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
         ds_os = ds.DataSourceOpenStack(
             settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp}))
         self.assertIsNone(ds_os.version)
-        found = ds_os.get_data()
+        mock_path = MOCK_PATH + 'detect_openstack'
+        with test_helpers.mock.patch(mock_path) as m_detect_os:
+            m_detect_os.return_value = True
+            found = ds_os.get_data()
         self.assertTrue(found)
         self.assertEqual(2, ds_os.version)
         md = dict(ds_os.metadata)
@@ -260,7 +265,10 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
             'broadcast-address': '192.168.2.255'}]
 
         self.assertIsNone(ds_os_local.version)
-        found = ds_os_local.get_data()
+        mock_path = MOCK_PATH + 'detect_openstack'
+        with test_helpers.mock.patch(mock_path) as m_detect_os:
+            m_detect_os.return_value = True
+            found = ds_os_local.get_data()
         self.assertTrue(found)
         self.assertEqual(2, ds_os_local.version)
         md = dict(ds_os_local.metadata)
@@ -284,7 +292,10 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
                                        None,
                                        helpers.Paths({'run_dir': self.tmp}))
         self.assertIsNone(ds_os.version)
-        found = ds_os.get_data()
+        mock_path = MOCK_PATH + 'detect_openstack'
+        with test_helpers.mock.patch(mock_path) as m_detect_os:
+            m_detect_os.return_value = True
+            found = ds_os.get_data()
         self.assertFalse(found)
         self.assertIsNone(ds_os.version)
         self.assertIn(
@@ -306,15 +317,16 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
             'timeout': 0,
         }
         self.assertIsNone(ds_os.version)
-        found = ds_os.get_data()
+        mock_path = MOCK_PATH + 'detect_openstack'
+        with test_helpers.mock.patch(mock_path) as m_detect_os:
+            m_detect_os.return_value = True
+            found = ds_os.get_data()
         self.assertFalse(found)
         self.assertIsNone(ds_os.version)
 
     def test_network_config_disabled_by_datasource_config(self):
         """The network_config can be disabled from datasource config."""
-        mock_path = (
-            'cloudinit.sources.DataSourceOpenStack.openstack.'
-            'convert_net_json')
+        mock_path = MOCK_PATH + 'openstack.convert_net_json'
         ds_os = ds.DataSourceOpenStack(
             settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp}))
         ds_os.ds_cfg = {'apply_network_config': False}
@@ -327,9 +339,7 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
 
     def test_network_config_from_network_json(self):
         """The datasource gets network_config from network_data.json."""
-        mock_path = (
-            'cloudinit.sources.DataSourceOpenStack.openstack.'
-            'convert_net_json')
+        mock_path = MOCK_PATH + 'openstack.convert_net_json'
         example_cfg = {'version': 1, 'config': []}
         ds_os = ds.DataSourceOpenStack(
             settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp}))
@@ -345,9 +355,7 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
 
     def test_network_config_cached(self):
         """The datasource caches the network_config property."""
-        mock_path = (
-            'cloudinit.sources.DataSourceOpenStack.openstack.'
-            'convert_net_json')
+        mock_path = MOCK_PATH + 'openstack.convert_net_json'
         example_cfg = {'version': 1, 'config': []}
         ds_os = ds.DataSourceOpenStack(
             settings.CFG_BUILTIN, None, helpers.Paths({'run_dir': self.tmp}))
@@ -374,7 +382,10 @@ class TestOpenStackDataSource(test_helpers.HttprettyTestCase):
             'timeout': 0,
         }
         self.assertIsNone(ds_os.version)
-        found = ds_os.get_data()
+        mock_path = MOCK_PATH + 'detect_openstack'
+        with test_helpers.mock.patch(mock_path) as m_detect_os:
+            m_detect_os.return_value = True
+            found = ds_os.get_data()
         self.assertFalse(found)
         self.assertIsNone(ds_os.version)
 
@@ -438,4 +449,89 @@ class TestVendorDataLoading(test_helpers.TestCase):
         data = {'foo': 'bar', 'cloud-init': ['VD_1', 'VD_2']}
         self.assertEqual(self.cvj(data), data['cloud-init'])
 
+
+@test_helpers.mock.patch(MOCK_PATH + 'util.is_x86')
+class TestDetectOpenStack(test_helpers.CiTestCase):
+
+    def test_detect_openstack_non_intel_x86(self, m_is_x86):
+        """Return True on non-intel platforms because dmi isn't conclusive."""
+        m_is_x86.return_value = False
+        self.assertTrue(
+            ds.detect_openstack(), 'Expected detect_openstack == True')
+
+    @test_helpers.mock.patch(MOCK_PATH + 'util.get_proc_env')
+    @test_helpers.mock.patch(MOCK_PATH + 'util.read_dmi_data')
+    def test_not_detect_openstack_intel_x86_ec2(self, m_dmi, m_proc_env,
+                                                m_is_x86):
+        """Return False on EC2 platforms."""
+        m_is_x86.return_value = True
+        # No product_name in proc/1/environ
+        m_proc_env.return_value = {'HOME': '/'}
+
+        def fake_dmi_read(dmi_key):
+            if dmi_key == 'system-product-name':
+                return 'HVM domU'  # Nothing 'openstackish' on EC2
+            if dmi_key == 'chassis-asset-tag':
+                return ''  # Empty string on EC2
+            assert False, 'Unexpected dmi read of %s' % dmi_key
+
+        m_dmi.side_effect = fake_dmi_read
+        self.assertFalse(
+            ds.detect_openstack(), 'Expected detect_openstack == False on EC2')
+        m_proc_env.assert_called_with(1)
+
+    @test_helpers.mock.patch(MOCK_PATH + 'util.read_dmi_data')
+    def test_detect_openstack_intel_product_name_compute(self, m_dmi,
+                                                         m_is_x86):
+        """Return True on OpenStack compute and nova instances."""
+        m_is_x86.return_value = True
+        openstack_product_names = ['OpenStack Nova', 'OpenStack Compute']
+
+        for product_name in openstack_product_names:
+            m_dmi.return_value = product_name
+            self.assertTrue(
+                ds.detect_openstack(), 'Failed to detect_openstack')
+
+    @test_helpers.mock.patch(MOCK_PATH + 'util.read_dmi_data')
+    def test_detect_openstack_opentelekomcloud_chassis_asset_tag(self, m_dmi,
+                                                                 m_is_x86):
+        """Return True on OpenStack reporting OpenTelekomCloud asset-tag."""
+        m_is_x86.return_value = True
+
+        def fake_dmi_read(dmi_key):
+            if dmi_key == 'system-product-name':
+                return 'HVM domU'  # Nothing 'openstackish' on OpenTelekomCloud
+            if dmi_key == 'chassis-asset-tag':
+                return 'OpenTelekomCloud'
+            assert False, 'Unexpected dmi read of %s' % dmi_key
+
+        m_dmi.side_effect = fake_dmi_read
+        self.assertTrue(
+            ds.detect_openstack(),
+            'Expected detect_openstack == True on OpenTelekomCloud')
+
+    @test_helpers.mock.patch(MOCK_PATH + 'util.get_proc_env')
+    @test_helpers.mock.patch(MOCK_PATH + 'util.read_dmi_data')
+    def test_detect_openstack_by_proc_1_environ(self, m_dmi, m_proc_env,
+                                                m_is_x86):
+        """Return True when nova product_name specified in /proc/1/environ."""
+        m_is_x86.return_value = True
+        # Nova product_name in proc/1/environ
+        m_proc_env.return_value = {
+            'HOME': '/', 'product_name': 'OpenStack Nova'}
+
+        def fake_dmi_read(dmi_key):
+            if dmi_key == 'system-product-name':
+                return 'HVM domU'  # Nothing 'openstackish'
+            if dmi_key == 'chassis-asset-tag':
+                return ''  # Nothin 'openstackish'
+            assert False, 'Unexpected dmi read of %s' % dmi_key
+
+        m_dmi.side_effect = fake_dmi_read
+        self.assertTrue(
+            ds.detect_openstack(),
+            'Expected detect_openstack == True on OpenTelekomCloud')
+        m_proc_env.assert_called_with(1)
+
+
 # vi: ts=4 expandtab
diff --git a/tests/unittests/test_util.py b/tests/unittests/test_util.py
index 20479f66..7a203ce2 100644
--- a/tests/unittests/test_util.py
+++ b/tests/unittests/test_util.py
@@ -468,6 +468,29 @@ class TestMountinfoParsing(helpers.ResourceUsingTestCase):
         self.assertIsNone(ret)
 
 
+class TestIsX86(helpers.CiTestCase):
+
+    def test_is_x86_matches_x86_types(self):
+        """is_x86 returns True if CPU architecture matches."""
+        matched_arches = ['x86_64', 'i386', 'i586', 'i686']
+        for arch in matched_arches:
+            self.assertTrue(
+                util.is_x86(arch), 'Expected is_x86 for arch "%s"' % arch)
+
+    def test_is_x86_unmatched_types(self):
+        """is_x86 returns Fale on non-intel x86 architectures."""
+        unmatched_arches = ['ia64', '9000/800', 'arm64v71']
+        for arch in unmatched_arches:
+            self.assertFalse(
+                util.is_x86(arch), 'Expected not is_x86 for arch "%s"' % arch)
+
+    @mock.patch('cloudinit.util.os.uname')
+    def test_is_x86_calls_uname_for_architecture(self, m_uname):
+        """is_x86 returns True if platform from uname matches."""
+        m_uname.return_value = [0, 1, 2, 3, 'x86_64']
+        self.assertTrue(util.is_x86())
+
+
 class TestReadDMIData(helpers.FilesystemMockingTestCase):
 
     def setUp(self):