Allows to configure a dedicated migration network.

This commits adds a new extra binding (migration) and
its corresponding fallback configuration flag (libvirt-
migration-network) that allows to specify a space or an
existing CIDR formatted network (if the config flag is pre-
ferred) that will be seleced as the inbound address to be used
as a the live migration target.

For the case of any openstack release >= ocata,
the live_migration_inbound_addr variable will be set
as well as the libvirt_migration_scheme (set to SSH
by default).

For older releases, the behavior remains as before,
as the only remaining option is to setup libvirt
to bind in a insecure tcp connection, so we keep it
as the current live_migration_uri.

The reason of not using an extra-binding exclusively relies
on the back-compability of the change, this needs
to be applied on existing clouds where updating
the bindings on deployed application
isn't possible due to LP: #1796653.

For fresh/new deployments, the migration extra-binding
has been defined and used with precedence over the
libvirt-migration-network variable.

Change-Id: I2f8c0a1e822ad6a90e23cd8009e181b8f86d765a
Closes-Bug: #1680531
Signed-off-by: Jorge Niedbalski <jnr@metaklass.org>

config.yaml

@@ -534,3 +534,18 @@ options:
     description: |
       Ensure notifications are included in the log files. It will set an additional
       log driver for oslo messaging notifications.
+  libvirt-migration-network:
+    type: string
+    default:
+    description: |
+      Specify a network in cidr notation (192.168.0.0/24),
+      which directs libvirt to use a specific network
+      address as the live_migration_inbound_addr to make
+      use of a dedicated migration network if possible.
+      .
+      Please note that if the migration binding has been
+      declared and set, the primary address for that space has precedence
+      over this configuration option.
+      .
+      This option doesn't have any effect on clouds running
+      a release < Ocata.

hooks/nova_compute_context.py

@@ -21,6 +21,7 @@ import uuid
 
 from charmhelpers.core.unitdata import kv
 from charmhelpers.contrib.openstack import context
+
 from charmhelpers.core.host import (
     lsb_release,
     CompareHostReleases,
@@ -53,7 +54,6 @@ from charmhelpers.contrib.network.ip import (
     get_relation_ip,
 )
 
-
 # This is just a label and it must be consistent across
 # nova-compute nodes to support live migration.
 CEPH_SECRET_UUID = '514c9fca-8cbe-11e2-9c52-3bc8c7819472'
@@ -199,7 +199,13 @@ class NovaComputeLibvirtContext(context.OSContextGenerator):
 
         if config('enable-live-migration') and \
                 config('migration-auth-type') == 'ssh':
-            # nova.conf
+            migration_address = get_relation_ip(
+                'migration', cidr_network=config('libvirt-migration-network'))
+
+            if cmp_os_release >= 'ocata':
+                ctxt['live_migration_scheme'] = config('migration-auth-type')
+                ctxt['live_migration_inbound_addr'] = migration_address
+            else:
                 ctxt['live_migration_uri'] = 'qemu+ssh://%s/system'
 
         if config('enable-live-migration'):

metadata.yaml

@@ -24,6 +24,7 @@ provides:
     scope: container
 extra-bindings:
   internal:
+  migration:
 requires:
   amqp:
     interface: rabbitmq

templates/ocata/nova.conf

@@ -215,6 +215,12 @@ rbd_secret_uuid = {{ rbd_secret_uuid }}
 {% if live_migration_uri -%}
 live_migration_uri = {{ live_migration_uri }}
 {% endif -%}
+{% if live_migration_scheme -%}
+live_migration_scheme = {{ live_migration_scheme }}
+{% endif -%}
+{% if live_migration_inbound_addr -%}
+live_migration_inbound_addr = {{ live_migration_inbound_addr }}
+{% endif -%}
 {% if live_migration_permit_post_copy -%}
 live_migration_permit_post_copy = {{ live_migration_permit_post_copy }}
 {% endif -%}

templates/pike/nova.conf

@@ -223,6 +223,12 @@ rbd_secret_uuid = {{ rbd_secret_uuid }}
 {% if live_migration_uri -%}
 live_migration_uri = {{ live_migration_uri }}
 {% endif -%}
+{% if live_migration_scheme -%}
+live_migration_scheme = {{ live_migration_scheme }}
+{% endif -%}
+{% if live_migration_inbound_addr -%}
+live_migration_inbound_addr = {{ live_migration_inbound_addr }}
+{% endif -%}
 {% if live_migration_permit_post_copy -%}
 live_migration_permit_post_copy = {{ live_migration_permit_post_copy }}
 {% endif -%}

templates/queens/nova.conf

@@ -235,6 +235,12 @@ rbd_secret_uuid = {{ rbd_secret_uuid }}
 {% if live_migration_uri -%}
 live_migration_uri = {{ live_migration_uri }}
 {% endif -%}
+{% if live_migration_scheme -%}
+live_migration_scheme = {{ live_migration_scheme }}
+{% endif -%}
+{% if live_migration_inbound_addr -%}
+live_migration_inbound_addr = {{ live_migration_inbound_addr }}
+{% endif -%}
 {% if live_migration_permit_post_copy -%}
 live_migration_permit_post_copy = {{ live_migration_permit_post_copy }}
 {% endif -%}

templates/rocky/nova.conf

@@ -235,6 +235,12 @@ rbd_secret_uuid = {{ rbd_secret_uuid }}
 {% if live_migration_uri -%}
 live_migration_uri = {{ live_migration_uri }}
 {% endif -%}
+{% if live_migration_scheme -%}
+live_migration_scheme = {{ live_migration_scheme }}
+{% endif -%}
+{% if live_migration_inbound_addr -%}
+live_migration_inbound_addr = {{ live_migration_inbound_addr }}
+{% endif -%}
 {% if live_migration_permit_post_copy -%}
 live_migration_permit_post_copy = {{ live_migration_permit_post_copy }}
 {% endif -%}

unit_tests/test_nova_compute_contexts.py

@@ -56,6 +56,10 @@ def fake_log(msg, level=None):
     print('[juju test log ({})] {}'.format(level, msg))
 
 
+def raise_no_space(self):
+    raise context.NoNetworkBinding
+
+
 class FakeUnitdata(object):
 
     def __init__(self, **kwargs):
@@ -344,6 +348,40 @@ class NovaComputeContextTests(CharmTestCase):
              'force_raw_images': True,
              'reserved_host_memory': 512}, libvirt())
 
+    def test_libvirt_context_without_migration_network(self):
+        self.kv.return_value = FakeUnitdata(**{'host_uuid': self.host_uuid})
+        self.lsb_release.return_value = {'DISTRIB_CODENAME': 'xenial'}
+        self.test_config.set('enable-live-migration', True)
+        self.test_config.set('migration-auth-type', 'ssh')
+        self.os_release.return_value = 'kilo'
+        self.assertEquals(context.NovaComputeLibvirtContext()()[
+                          'live_migration_uri'], 'qemu+ssh://%s/system')
+
+    def test_libvirt_context_with_migration_network(self):
+        self.kv.return_value = FakeUnitdata(**{'host_uuid': self.host_uuid})
+        self.lsb_release.return_value = {'DISTRIB_CODENAME': 'xenial'}
+        self.test_config.set('enable-live-migration', True)
+        self.test_config.set('migration-auth-type', 'ssh')
+        self.test_config.set('libvirt-migration-network', '10.5.0.0/16')
+        self.os_release.return_value = 'rocky'
+        context.NovaComputeLibvirtContext()()
+        self.get_relation_ip.assert_called_with('migration',
+                                                cidr_network="10.5.0.0/16")
+
+    def test_libvirt_context_with_migration_space(self):
+        self.kv.return_value = FakeUnitdata(**{'host_uuid': self.host_uuid})
+        self.lsb_release.return_value = {'DISTRIB_CODENAME': 'xenial'}
+        self.test_config.set('enable-live-migration', True)
+        self.os_release.return_value = 'ocata'
+        self.get_relation_ip.return_value = "10.5.0.5"
+        libvirt_context = context.NovaComputeLibvirtContext()()
+        self.get_relation_ip.assert_called_with('migration',
+                                                cidr_network=None)
+        self.assertTrue('live_migration_uri' not in libvirt_context.keys())
+        self.assertEquals(libvirt_context['live_migration_scheme'], 'ssh')
+        self.assertEquals(libvirt_context['live_migration_inbound_addr'],
+                          '10.5.0.5')
+
     def test_libvirt_bin_context_migration_tcp_listen_with_auto_converge(self):
         self.kv.return_value = FakeUnitdata(**{'host_uuid': self.host_uuid})
         self.lsb_release.return_value = {'DISTRIB_CODENAME': 'lucid'}