Fix traceback when running nova-console

Recently utils.last_bytes has moved to libvirt/utils.py in nova.
(2341a41eaee5152e95379e5ed38012270af82ef5). Duplicate the function
that was in nova/utils.py.

Also includes a fix for nova-lxd's gate:
Update test-requirements with wsgi-intercept

Closes-Bug: #1707096

Change-Id: Ie77c8e67e29e8a01bbf58ab9277c5110cd7c112e
Signed-off-by: Chuck Short <charles.short@ericsson.com>>

devstack/tempest-dsvm-lxd-rc

@@ -36,7 +36,7 @@ r="$r|(?:tempest\.scenario\.test_minimum_basic\.TestMinimumBasicScenario\.test_m
 
 # XXX: zulcss (18 Oct 2016) nova-lxd does not support booting from ebs volumes
 r="$r|(?:tempest\.scenario\.test_volume_boot_pattern.*)"
-
+r="$r|(?:tempest\.api\.compute\.servers\.test_create_server\.ServersTestBootFromVolume)"
 # XXX: zulcss (18 Oct 2016) tempest test only passes when there is more than 10 lines in the
 #  console output, and cirros LXD consoles have only a single line of output
 r="$r|(?:tempest\.api\.compute\.servers\.test_server_actions\.ServerActionsTestJSON\.test_get_console_output_with_unlimited_size)"

nova/virt/lxd/driver.py

@@ -15,6 +15,7 @@
 
 from __future__ import absolute_import
 
+import errno
 import io
 import json
 import os
@@ -95,6 +96,30 @@ BASE_DIR = os.path.join(
     CONF.instances_path, CONF.image_cache_subdirectory_name)
 
 
+def _last_bytes(file_like_object, num):
+    """Return num bytes from the end of the file, and remaning byte count.
+
+    :param file_like_object: The file to read
+    :param num: The number of bytes to return
+
+    :returns: (data, remaining)
+    """
+
+    try:
+        file_like_object.seek(-num, os.SEEK_END)
+    except IOError as e:
+        # seek() fails with EINVAL when trying to go before the start of
+        # the file. It means that num is larger than the file size, so
+        # just go to the start.
+        if e.errno == errno.EINVAL:
+            file_like_object.seek(0, os.SEEK_SET)
+        else:
+            raise
+
+    remaining = file_like_object.tell()
+    return (file_like_object.read(), remaining)
+
+
 def _neutron_failed_callback(event_name, instance):
     LOG.error('Neutron Reported failure on event '
               '%(event)s for instance %(uuid)s',
@@ -591,7 +616,7 @@ class LXDDriver(driver.ComputeDriver):
         utils.execute(
             'chmod', '755', instance_attrs.container_path, run_as_root=True)
         with open(console_path, 'rb') as f:
-            log_data, _ = utils.last_bytes(f, MAX_CONSOLE_BYTES)
+            log_data, _ = _last_bytes(f, MAX_CONSOLE_BYTES)
             return log_data
 
     def get_host_ip_addr(self):

test-requirements.txt

@@ -15,3 +15,4 @@ testscenarios>=0.4 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT
 os-testr>=0.8.0 # Apache-2.0
 nosexcover # BSD
+wsgi-intercept>=1.4.1 # MIT License