Fix nits for supporting non-glance images

Addresses some comments that were posted in change
Iec8e1f862d29639363b71c67d60e711d35d2ed94 on last patch set.

Change-Id: Idf35eb1a603714973dd0522f8e1207c8894f349b

doc/source/deploy/install-guide.rst

@@ -993,13 +993,13 @@ It's possible to use Ironic without other OpenStack services.
 
 You should make the following changes to ``/etc/ironic/ironic.conf``:
 
-#. To disable usage of keystone tokens::
+#. To disable usage of Keystone tokens::
 
     [DEFAULT]
     ...
     auth_strategy=none
 
-#. If you want to disable neutron, you should have your network pre-configured
+#. If you want to disable Neutron, you should have your network pre-configured
    to serve DHCP and TFTP for machines that you're deploying. To disable it,
    change the following lines::
 
@@ -1007,6 +1007,17 @@ You should make the following changes to ``/etc/ironic/ironic.conf``:
     ...
     dhcp_provider=none
 
+   .. note::
+      If you disabled Neutron and driver that you use is supported by at most
+      one conductor, PXE boot will still work for your nodes without any
+      manual config editing. This is because you know all the DHCP options
+      that will be used for deployment and can set up your DHCP server
+      appropriately.
+
+      If you have multiple conductors per driver, it would be better to use
+      Neutron since it will do all the dynamically changing configurations for
+      you.
+
 If you don't use Glance, it's possible to provide images to Ironic via hrefs.
 
 .. note::

ironic/common/images.py

@@ -308,7 +308,7 @@ def converted_size(path):
 
 
 def get_image_properties(context, image_href, properties="all"):
-    """Returns the values of several properties of a glance image
+    """Returns the values of several properties of an image
 
     :param context: context
     :param image_href: href of the image

ironic/drivers/modules/agent.py

@@ -171,7 +171,10 @@ def build_instance_info_for_deploy(task):
             image_service.HttpImageService().validate_href(image_source)
         except exception.ImageRefValidationFailed:
             with excutils.save_and_reraise_exception():
-                LOG.error(_LE("Agent deploy supports only HTTP(S) URLs."))
+                LOG.error(_LE("Agent deploy supports only HTTP(S) URLs as "
+                              "instance_info['image_source']. Either %s "
+                              "is not a valid HTTP(S) URL or "
+                              "is not reachable."), image_source)
         instance_info['image_url'] = image_source
 
     return instance_info

ironic/drivers/modules/ilo/deploy.py

@@ -107,8 +107,11 @@ def _get_boot_iso(task, root_uuid):
                 image_service.HttpImageService().validate_href(boot_iso)
             except exception.ImageRefValidationFailed:
                 with excutils.save_and_reraise_exception():
-                    LOG.error(_LE("Ilo can attach only HTTP(S) URL as "
+                    LOG.error(_LE("Virtual media deploy accepts only Glance "
-                                  "virtual media."))
+                                  "images or HTTP(S) URLs as "
+                                  "instance_info['ilo_boot_iso']. Either %s "
+                                  "is not a valid HTTP(S) URL or is "
+                                  "not reachable."), boot_iso)
         return task.node.instance_info['ilo_boot_iso']
 
     # Option 2 - Check if user has provided a boot_iso in Glance. If boot_iso