Add ability to provide another ephemeral storage for nova-compute

Nova has configuration option to specify ephemeral storage - images_type
But right now this charm allows to specify only ceph via relation to ceph.
This changeset adds ability to specify any images_type and add ability
to provide configuration for the ephemeral backend via relation.
Same functionality implemented in cinder charm via storage-backend interface.

Change-Id: Id851e172aed53723d4d8fb6623ff1c4b4a03fefa

hooks/ephemeral-backend-relation-broken

@@ -0,0 +1 @@
+nova_compute_hooks.py

hooks/ephemeral-backend-relation-changed

@@ -0,0 +1 @@
+nova_compute_hooks.py

hooks/nova_compute_context.py

@@ -149,6 +149,9 @@ class NovaComputeLibvirtContext(context.OSContextGenerator):
             db.flush()
             ctxt['host_uuid'] = host_uuid
 
+        if config('libvirt-image-backend'):
+            ctxt['libvirt_images_type'] = config('libvirt-image-backend')
+
         return ctxt
 
 
@@ -169,7 +172,7 @@ class NovaComputeVirtContext(context.OSContextGenerator):
         return {}
 
 
-def assert_libvirt_imagebackend_allowed():
+def assert_libvirt_rbd_imagebackend_allowed():
     os_rel = "Juno"
     os_ver = get_os_version_package('nova-common')
     if float(os_ver) < float(get_os_version_codename(os_rel.lower())):
@@ -196,11 +199,8 @@ class NovaComputeCephContext(context.CephContext):
         ctxt['rbd_pool'] = config('rbd-pool')
 
         if (config('libvirt-image-backend') == 'rbd' and
-                assert_libvirt_imagebackend_allowed()):
-            ctxt['libvirt_images_type'] = 'rbd'
+                assert_libvirt_rbd_imagebackend_allowed()):
             ctxt['libvirt_rbd_images_ceph_conf'] = ceph_config_file()
-        elif config('libvirt-image-backend') == 'lvm':
-            ctxt['libvirt_images_type'] = 'lvm'
 
         rbd_cache = config('rbd-client-cache') or ""
         if rbd_cache.lower() == "enabled":

hooks/nova_compute_hooks.py

@@ -83,7 +83,7 @@ from charmhelpers.core.unitdata import kv
 
 from nova_compute_context import (
     CEPH_SECRET_UUID,
-    assert_libvirt_imagebackend_allowed
+    assert_libvirt_rbd_imagebackend_allowed
 )
 from charmhelpers.contrib.charmsupport import nrpe
 from charmhelpers.core.sysctl import create as create_sysctl
@@ -173,7 +173,7 @@ def config_changed():
         set_ppc64_cpu_smt_state('off')
 
     if (config('libvirt-image-backend') == 'rbd' and
-            assert_libvirt_imagebackend_allowed()):
+            assert_libvirt_rbd_imagebackend_allowed()):
         for rid in relation_ids('ceph'):
             for unit in related_units(rid):
                 ceph_changed(rid=rid, unit=unit)
@@ -252,6 +252,16 @@ def image_service_changed():
     CONFIGS.write(NOVA_CONF)
 
 
+@hooks.hook('ephemeral-backend-relation-changed',
+            'ephemeral-backend-relation-broken')
+@restart_on_change(restart_map())
+def ephemeral_backend_hook():
+    if 'ephemeral-backend' not in CONFIGS.complete_contexts():
+        log('ephemeral-backend relation incomplete. Peer not ready?')
+        return
+    CONFIGS.write(NOVA_CONF)
+
+
 @hooks.hook('cloud-compute-relation-joined')
 def compute_joined(rid=None):
     # NOTE(james-page) in MAAS environments the actual hostname is a CNAME
@@ -325,7 +335,7 @@ def ceph_changed(rid=None, unit=None):
                               secret_uuid=CEPH_SECRET_UUID, key=key)
 
     if (config('libvirt-image-backend') == 'rbd' and
-            assert_libvirt_imagebackend_allowed()):
+            assert_libvirt_rbd_imagebackend_allowed()):
         if is_request_complete(get_ceph_request()):
             log('Request complete')
             # Ensure that nova-compute is restarted since only now can we

hooks/nova_compute_utils.py

@@ -174,7 +174,8 @@ BASE_RESOURCE_MAP = {
                      NovaComputeCephContext(),
                      context.SyslogContext(),
                      context.SubordinateConfigContext(
-                         interface=['neutron-plugin', 'nova-ceilometer'],
+                         interface=['neutron-plugin', 'nova-ceilometer',
+                                    'ephemeral-backend'],
                          service=['nova-compute', 'nova'],
                          config_file=NOVA_CONF),
                      InstanceConsoleContext(),

metadata.yaml

@@ -41,6 +41,9 @@ requires:
   zeromq-configuration:
     interface: zeromq-configuration
     scope: container
+  ephemeral-backend:
+    interface: ephemeral-backend
+    scope: container
 peers:
   compute-peer:
     interface: nova

templates/icehouse/nova.conf

@@ -155,8 +155,10 @@ cpu_mode = {{ cpu_mode }}
 {% if cpu_model -%}
 cpu_model = {{ cpu_model }}
 {% endif -%}
-{% if libvirt_images_type and rbd_pool -%}
+{% if libvirt_images_type -%}
 images_type = {{ libvirt_images_type }}
+{% endif -%}
+{% if libvirt_images_type and rbd_pool -%}
 images_rbd_pool = {{ rbd_pool }}
 images_rbd_ceph_conf = {{ libvirt_rbd_images_ceph_conf }}
 inject_password = false
@@ -169,3 +171,4 @@ rbd_secret_uuid = {{ rbd_secret_uuid }}
 disk_cachemodes = {{ disk_cachemodes }}
 {% endif -%}
 
+{% include "parts/section-ephemeral" %}

templates/juno/nova.conf

@@ -148,8 +148,10 @@ cpu_mode = {{ cpu_mode }}
 {% if cpu_model -%}
 cpu_model = {{ cpu_model }}
 {% endif -%}
-{% if libvirt_images_type and rbd_pool -%}
+{% if libvirt_images_type -%}
 images_type = {{ libvirt_images_type }}
+{% endif -%}
+{% if libvirt_images_type and rbd_pool -%}
 images_rbd_pool = {{ rbd_pool }}
 images_rbd_ceph_conf = {{ libvirt_rbd_images_ceph_conf }}
 inject_password = false
@@ -167,3 +169,4 @@ disk_cachemodes = {{ disk_cachemodes }}
 
 {% include "parts/section-cinder" %}
 
+{% include "parts/section-ephemeral" %}

templates/kilo/nova.conf

@@ -156,8 +156,10 @@ cpu_mode = {{ cpu_mode }}
 {% if cpu_model -%}
 cpu_model = {{ cpu_model }}
 {% endif -%}
-{% if libvirt_images_type and rbd_pool -%}
+{% if libvirt_images_type -%}
 images_type = {{ libvirt_images_type }}
+{% endif -%}
+{% if libvirt_images_type and rbd_pool -%}
 images_rbd_pool = {{ rbd_pool }}
 images_rbd_ceph_conf = {{ libvirt_rbd_images_ceph_conf }}
 inject_password = false
@@ -184,3 +186,5 @@ lock_path=/var/lock/nova
 
 [workarounds]
 disable_libvirt_livesnapshot = False
+
+{% include "parts/section-ephemeral" %}

templates/liberty/nova.conf

@@ -162,8 +162,10 @@ cpu_mode = {{ cpu_mode }}
 {% if cpu_model -%}
 cpu_model = {{ cpu_model }}
 {% endif -%}
-{% if libvirt_images_type and rbd_pool -%}
+{% if libvirt_images_type -%}
 images_type = {{ libvirt_images_type }}
+{% endif -%}
+{% if libvirt_images_type and rbd_pool -%}
 images_rbd_pool = {{ rbd_pool }}
 images_rbd_ceph_conf = {{ libvirt_rbd_images_ceph_conf }}
 inject_password = false
@@ -190,3 +192,5 @@ lock_path=/var/lock/nova
 
 [workarounds]
 disable_libvirt_livesnapshot = False
+
+{% include "parts/section-ephemeral" %}

templates/mitaka/nova.conf

@@ -161,8 +161,10 @@ cpu_mode = {{ cpu_mode }}
 {% if cpu_model -%}
 cpu_model = {{ cpu_model }}
 {% endif -%}
-{% if libvirt_images_type and rbd_pool -%}
+{% if libvirt_images_type -%}
 images_type = {{ libvirt_images_type }}
+{% endif -%}
+{% if libvirt_images_type and rbd_pool -%}
 images_rbd_pool = {{ rbd_pool }}
 images_rbd_ceph_conf = {{ libvirt_rbd_images_ceph_conf }}
 inject_password = false
@@ -189,3 +191,5 @@ lock_path=/var/lock/nova
 
 [workarounds]
 disable_libvirt_livesnapshot = False
+
+{% include "parts/section-ephemeral" %}

templates/parts/section-ephemeral

@@ -0,0 +1,8 @@
+{% for section in sections -%}
+{% if section != 'DEFAULT' -%}
+[{{ section }}]
+{% for key, value in sections[section] -%}
+{{ key }} = {{ value }}
+{% endfor %}
+{% endif %}
+{%- endfor %}

unit_tests/test_nova_compute_hooks.py

@@ -63,7 +63,7 @@ TO_PATCH = [
     # misc_utils
     'ensure_ceph_keyring',
     'execd_preinstall',
-    'assert_libvirt_imagebackend_allowed',
+    'assert_libvirt_rbd_imagebackend_allowed',
     'is_request_complete',
     'send_request_if_needed',
     # socket
@@ -467,7 +467,7 @@ class NovaComputeRelationsTests(CharmTestCase):
                                                      service_name):
         self.test_config.set('libvirt-image-backend', 'rbd')
         self.is_request_complete.return_value = True
-        self.assert_libvirt_imagebackend_allowed.return_value = True
+        self.assert_libvirt_rbd_imagebackend_allowed.return_value = True
         configs.complete_contexts = MagicMock()
         configs.complete_contexts.return_value = ['ceph']
         configs.write = MagicMock()