Allow cloud volume to provide a list of volumes for attach

While opening the view to attach a selected volume to a new instance,
the UI will currently ask for the VMs that are available in the cloud
tenant of the chosen volume. While it works for OpenStack, Amazon has no
notion of tenants currently.

Instead of relying on the tenant's VMs, this patch proposes a new method
in the cloud volume allowing it to specify the list of VMs this volume
can be attached to. In case of OpenStack, this will be delagated to
`cloud_tenant` and on Amazon it will be delagated to `availability_zone`
(because the volume has to reside in the same AZ).

A simple spec test is provided to validate the `available_vms` only
return the list of VMs in the same cloud tenant.

Signed-off-by: Gregor Berginc <gregor.berginc@xlab.si>

app/models/cloud_volume.rb

@@ -130,4 +130,7 @@ def raw_delete_volume
     raise NotImplementedError, _("raw_delete_volume must be implemented in a subclass")
   end
 
+  def available_vms
+    raise NotImplementedError, _("available_vms must be implemented in a subclass")
+  end
 end

app/models/manageiq/providers/openstack/cloud_manager/cloud_volume.rb

@@ -120,6 +120,10 @@ def create_volume_snapshot_queue(userid, options)
       .create_snapshot_queue(userid, self, options)
   end
 
+  def available_vms
+    cloud_tenant.vms
+  end
+
   def provider_object(connection)
     connection.volumes.get(ems_ref)
   end

spec/models/manageiq/providers/openstack/cloud_manager/cloud_volume_spec.rb

@@ -135,4 +135,15 @@
       end
     end
   end
+
+  describe "instance linsting for attaching volumes" do
+    let(:first_instance) { FactoryGirl.create(:vm_openstack, :ext_management_system => ems, :ems_ref => "instance_0", :cloud_tenant => tenant) }
+    let(:second_instance) { FactoryGirl.create(:vm_openstack, :ext_management_system => ems, :ems_ref => "instance_1", :cloud_tenant => tenant) }
+    let(:other_tenant) { FactoryGirl.create(:cloud_tenant_openstack, :ext_management_system => ems) }
+    let(:other_instance) { FactoryGirl.create(:vm_openstack, :ext_management_system => ems, :ems_ref => "instance_2", :cloud_tenant => other_tenant) }
+
+    it "supports attachment to only those instances that are in the same tenant" do
+      expect(cloud_volume.available_vms).to contain_exactly(first_instance, second_instance)
+    end
+  end
 end