Follow up to ISO image build patch

This change addresses a few nits pointed out in the Gerrit
review (Change-Id: Idf912ff2146434b666fdb4250dc1ecad39bc5a04).

Change-Id: I8668b02a2f46427567526189caa2040fc1e3b402
Story: 1526753
Task: 28098

ironic/common/images.py

@@ -261,18 +261,16 @@ def create_isolinux_image_for_uefi(output_file, kernel, ramdisk,
             # Open the deploy iso used to initiate deploy and copy the
             # efiboot.img i.e. boot loader to the current temporary
             # directory.
-            if deploy_iso:
+            if deploy_iso and not esp_image:
                 uefi_path_info, e_img_rel_path, grub_rel_path = (
                     _mount_deploy_iso(deploy_iso, mountdir))
 
                 grub_cfg = os.path.join(tmpdir, grub_rel_path)
 
             # Use ELF boot loader provided
-            elif esp_image:
+            elif esp_image and not deploy_iso:
                 e_img_rel_path = EFIBOOT_LOCATION
-                grub_rel_path = CONF.grub_config_path.strip()
-                while grub_rel_path.startswith(os.sep):
-                    grub_rel_path = grub_rel_path[1:]
+                grub_rel_path = CONF.grub_config_path.lstrip(' ' + os.sep)
                 grub_cfg = os.path.join(tmpdir, grub_rel_path)
 
                 uefi_path_info = {
@@ -281,9 +279,10 @@ def create_isolinux_image_for_uefi(output_file, kernel, ramdisk,
                 }
 
             else:
+                msg = _('Neither deploy ISO nor ESP image configured or '
+                        'both of them configured')
                 raise exception.ImageCreationFailed(
-                    image_type='iso',
-                    error='Neither `deploy_iso` nor `esp_image` configured')
+                    image_type='iso', error=msg)
 
             files_info.update(uefi_path_info)
 

ironic/conf/default.py

@@ -230,11 +230,12 @@ image_opts = [
                       'efficiently. ESP image should contain a '
                       'FAT12/16/32-formatted file system holding EFI boot '
                       'loaders (e.g. GRUB2) for each hardware architecture '
-                      'ironic needs to boot. If not configured, ironic '
-                      'will attempt to fetch ESP image from some remote '
-                      'store (if configured) or extract ESP image from '
-                      'UEFI-bootable deploy ISO image.')),
-
+                      'ironic needs to boot. This option is only used when '
+                      'neither ESP nor ISO deploy image is configured to '
+                      'the node being deployed in which case ironic will '
+                      'attempt to fetch ESP image from the configured '
+                      'location or extract ESP image from UEFI-bootable '
+                      'deploy ISO image.')),
 ]
 
 img_cache_opts = [

releasenotes/notes/build-iso-from-esp-d156036aa8ef85fb.yaml

@@ -5,7 +5,7 @@ features:
     building UEFI-bootable ISO images, in form of a local file or UUID
     or URI reference. The new ``[conductor]esp_image`` option can be used
     to configure ironic to use local file.
-other:
+fixes:
   - |
     Makes ironic building UEFI-only bootable ISO image (when being asked to
     build a UEFI-bootable image) rather than building a hybrid