targetuserspacecreator: Update err msg when installing the container

Regarding the changes around source OVL, we need to update the error
msg properly in case the installation of the target userspace container
fails. In this case, we want to change only the part when the upgrade
fails due to missing space.

repos/system_upgrade/common/actors/targetuserspacecreator/libraries/userspacegen.py

@@ -1,5 +1,6 @@
 import itertools
 import os
+import re
 import shutil
 
 from leapp import reporting
@@ -55,6 +56,7 @@
 PROD_CERTS_FOLDER = 'prod-certs'
 GPG_CERTS_FOLDER = 'rpm-gpg'
 PERSISTENT_PACKAGE_CACHE_DIR = '/var/lib/leapp/persistent_package_cache'
+DEDICATED_LEAPP_PART_URL = 'https://access.redhat.com/solutions/7011704'
 
 
 def _check_deprecated_rhsm_skip():
@@ -172,6 +174,53 @@ def _import_gpg_keys(context, install_root_dir, target_major_version):
         )
 
 
+def _handle_transaction_err_msg_size_old(err):
+    # NOTE(pstodulk): This is going to be removed in future!
+
+    article_section = 'Generic case'
+    xfs_info = next(api.consume(XFSPresence), XFSPresence())
+    if xfs_info.present and xfs_info.without_ftype:
+        article_section = 'XFS ftype=0 case'
+
+    message = ('There is not enough space on the file system hosting /var/lib/leapp directory '
+               'to extract the packages.')
+    details = {'hint': "Please follow the instructions in the '{}' section of the article at: "
+                       "link: https://access.redhat.com/solutions/5057391".format(article_section)}
+
+    raise StopActorExecutionError(message=message, details=details)
+
+
+def _handle_transaction_err_msg_size(err):
+    if get_env('LEAPP_OVL_LEGACY', '0') == '1':
+        _handle_transaction_err_msg_size_old(err)
+        return  # not needed actually as the above function raises error, but for visibility
+    NO_SPACE_STR = 'more space needed on the'
+
+    # Disk Requirements:
+    #   At least <size> more space needed on the <path> filesystem.
+    #
+    missing_space = [line.strip() for line in err.stderr.split('\n') if NO_SPACE_STR in line]
+    size_str = re.match(r'At least (.*) more space needed', missing_space[0]).group(1)
+    message = 'There is not enough space on the file system hosting /var/lib/leapp.'
+    hint = (
+        'Increase the free space on the filesystem hosting'
+        ' /var/lib/leapp by {} at minimum. It is suggested to provide'
+        ' reasonably more space to be able to perform all planned actions'
+        ' (e.g. when 200MB is missing, add 1700MB or more).\n\n'
+        'It is also a good practice to create dedicated partition'
+        ' for /var/lib/leapp when more space is needed, which can be'
+        ' dropped after the system upgrade is fully completed'
+        ' For more info, see: {}'
+        .format(size_str, DEDICATED_LEAPP_PART_URL)
+    )
+    # we do not want to confuse customers by the orig msg speaking about
+    # missing space on '/'. Skip the Disk Requirements section.
+    # The information is part of the hint.
+    details = {'hint': hint}
+
+    raise StopActorExecutionError(message=message, details=details)
+
+
 def prepare_target_userspace(context, userspace_dir, enabled_repos, packages):
     """
     Implement the creation of the target userspace.
@@ -210,21 +259,11 @@ def prepare_target_userspace(context, userspace_dir, enabled_repos, packages):
             message = 'Unable to install RHEL {} userspace packages.'.format(target_major_version)
             details = {'details': str(exc), 'stderr': exc.stderr}
 
-            xfs_info = next(api.consume(XFSPresence), XFSPresence())
             if 'more space needed on the' in exc.stderr:
                 # The stderr contains this error summary:
                 # Disk Requirements:
                 #   At least <size> more space needed on the <path> filesystem.
-
-                article_section = 'Generic case'
-                if xfs_info.present and xfs_info.without_ftype:
-                    article_section = 'XFS ftype=0 case'
-
-                message = ('There is not enough space on the file system hosting /var/lib/leapp directory '
-                           'to extract the packages.')
-                details = {'hint': "Please follow the instructions in the '{}' section of the article at: "
-                                   "link: https://access.redhat.com/solutions/5057391".format(article_section)}
-                raise StopActorExecutionError(message=message, details=details)
+                _handle_transaction_err_msg_size(exc)
 
             # If a proxy was set in dnf config, it should be the reason why dnf
             # failed since leapp does not support updates behind proxy yet.