CloudSigma: only poll on serial device after dmidecode check.

On systems with a ttyS1 and nothing attached, the read attempts
that the cloud sigma datasource would do would block.

Also, Add timeouts for reading/writting from/to the serial console

ChangeLog

@@ -1,6 +1,8 @@
 0.7.6:
  - open 0.7.6
  - Enable vendordata on CloudSigma datasource (LP: #1303986)
+ - Poll on /dev/ttyS1 in CloudSigma datasource only if dmidecode says
+   we're running on cloudsigma (LP: #1316475) [Kiril Vladimiroff]
 0.7.5:
  - open 0.7.5
  - Add a debug log message around import failures

cloudinit/cs_utils.py

@@ -35,6 +35,10 @@ import platform
 
 import serial
 
+# these high timeouts are necessary as read may read a lot of data.
+READ_TIMEOUT = 60
+WRITE_TIMEOUT = 10
+
 SERIAL_PORT = '/dev/ttyS1'
 if platform.system() == 'Windows':
     SERIAL_PORT = 'COM2'
@@ -76,7 +80,9 @@ class CepkoResult(object):
         self.result = self._marshal(self.raw_result)
 
     def _execute(self):
-        connection = serial.Serial(SERIAL_PORT)
+        connection = serial.Serial(port=SERIAL_PORT,
+                                   timeout=READ_TIMEOUT,
+                                   writeTimeout=WRITE_TIMEOUT)
         connection.write(self.request)
         return connection.readline().strip('\x04\n')
 

cloudinit/sources/DataSourceCloudSigma.py

@@ -16,10 +16,12 @@
 #    You should have received a copy of the GNU General Public License
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 from base64 import b64decode
+import os
 import re
 
 from cloudinit import log as logging
 from cloudinit import sources
+from cloudinit import util
 from cloudinit.cs_utils import Cepko
 
 LOG = logging.getLogger(__name__)
@@ -40,12 +42,40 @@ class DataSourceCloudSigma(sources.DataSource):
         self.ssh_public_key = ''
         sources.DataSource.__init__(self, sys_cfg, distro, paths)
 
+    def is_running_in_cloudsigma(self):
+        """
+        Uses dmidecode to detect if this instance of cloud-init is running
+        in the CloudSigma's infrastructure.
+        """
+        uname_arch = os.uname()[4]
+        if uname_arch.startswith("arm") or uname_arch == "aarch64":
+            # Disabling because dmidecode in CMD_DMI_SYSTEM crashes kvm process
+            LOG.debug("Disabling CloudSigma datasource on arm (LP: #1243287)")
+            return False
+
+        dmidecode_path = util.which('dmidecode')
+        if not dmidecode_path:
+            return False
+
+        LOG.debug("Determining hypervisor product name via dmidecode")
+        try:
+            cmd = [dmidecode_path, "--string", "system-product-name"]
+            system_product_name, _ = util.subp(cmd)
+            return 'cloudsigma' in system_product_name.lower()
+        except:
+            LOG.warn("Failed to get hypervisor product name via dmidecode")
+
+        return False
+
     def get_data(self):
         """
         Metadata is the whole server context and /meta/cloud-config is used
         as userdata.
         """
         dsmode = None
+        if not self.is_running_in_cloudsigma():
+            return False
+
         try:
             server_context = self.cepko.all().result
             server_meta = server_context['meta']

tests/unittests/test_datasource/test_cloudsigma.py

@@ -39,6 +39,7 @@ class CepkoMock(Cepko):
 class DataSourceCloudSigmaTest(TestCase):
     def setUp(self):
         self.datasource = DataSourceCloudSigma.DataSourceCloudSigma("", "", "")
+        self.datasource.is_running_in_cloudsigma = lambda: True
         self.datasource.cepko = CepkoMock(SERVER_CONTEXT)
         self.datasource.get_data()