upgradeinitramfsgenerator: Check the free space prior the initeramfs …

…generation

Under rare conditions it's possible the last piece free space
is consumed when the upgrade initramfs is generated. It's hard
to hit this problems right now without additional customisations
that consume more space than we expect. However, when it happens,
it not good situation. From this point, check the remaining free
space on the FS hosting the container. In case we have less than
500MB, do not even try. Possibly we will increase the value in future,
but consider it good enough for now.

repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/libraries/upgradeinitramfsgenerator.py

@@ -20,6 +20,7 @@
 
 INITRAM_GEN_SCRIPT_NAME = 'generate-initram.sh'
 DRACUT_DIR = '/dracut'
+DEDICATED_LEAPP_PART_URL = 'https://access.redhat.com/solutions/7011704'
 
 
 def _get_target_kernel_version(context):
@@ -231,13 +232,85 @@ def _update_files(copy_files):
     _copy_files(context, files)
 
 
+def _get_fspace(path, convert_to_mibs=False, coefficient=1):
+    """
+    Return the free disk space on given path.
+
+    The default is in bytes, but if convert_to_mibs is True, return MiBs instead.
+
+    Raises OSError if nothing exists on the given `path`.
+
+    :param path: Path to an existing file or directory
+    :type path: str
+    :param convert_to_mibs: If True, convert the value to MiBs
+    :type convert_to_mibs: bool
+    :param coefficient: Coefficient to multiply the free space (e.g. 0.9 to have it 10% lower). Max: 1
+    :type coefficient: float
+    :rtype: int
+    """
+    # TODO(pstodulk): discuss the function params
+    # NOTE(pstodulk): This func is copied from the overlaygen.py lib
+    # probably it would make sense to make it public in the utils.py lib,
+    # but for now, let's keep it private
+    stat = os.statvfs(path)
+
+    coefficient = min(coefficient, 1)
+    fspace_bytes = int(stat.f_frsize * stat.f_bavail * coefficient)
+    if convert_to_mibs:
+        return int(fspace_bytes / 1024 / 1024)  # noqa: W1619; pylint: disable=old-division
+    return fspace_bytes
+
+
+def _check_free_space(context):
+    """
+    Raise StopActorExecutionError if there is less than 500MB of free space available.
+
+    If there is not enough free space in the context, the initramfs will not be
+    generated successfully and it's hard to discover what was the issue. Also
+    the missing space is able to kill the leapp itself - trying to write to the
+    leapp.db when the FS hosting /var/lib/leapp is full, kills the framework
+    and the actor execution too - so there is no gentle way to handle such
+    exceptions when it happens. From this point, let's rather check the available
+    space in advance and stop the execution when it happens.
+
+    It is not expected to hit this issue, but I was successful and I know
+    it's still possible even with all other changes (just it's much harder
+    now to hit it). So adding this seatbelt, that is not 100% bulletproof,
+    but I call it good enough.
+
+    Currently protecting last 500MB. In case of problems, we can increase
+    the value.
+    """
+    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 500MB at minimum (suggested 1500MB).\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(DEDICATED_LEAPP_PART_URL)
+    )
+    detail = (
+        'Remaining free space is lower than 500MB which is not enough to'
+        ' be able to generate the upgrade initramfs. '
+    )
+
+    if _get_fspace(context.base_dir, convert_to_mibs=True) < 500:
+        raise StopActorExecutionError(
+            message=message,
+            details={'hint': hint, 'detail': detail}
+        )
+
+
 def generate_initram_disk(context):
     """
     Function to actually execute the init ramdisk creation.
 
     Includes handling of specified dracut and kernel modules from the host when
     needed. The check for the 'conflicting' modules is in a separate actor.
     """
+    _check_free_space(context)
     env = {}
     if get_target_major_version() == '9':
         env = {'SYSTEMD_SECCOMP': '0'}

repos/system_upgrade/common/actors/initramfs/upgradeinitramfsgenerator/tests/unit_test_upgradeinitramfsgenerator.py

@@ -10,6 +10,7 @@
 from leapp.utils.deprecation import suppress_deprecation
 
 from leapp.models import (  # isort:skip
+    FIPSInfo,
     RequiredUpgradeInitramPackages,  # deprecated
     UpgradeDracutModule,  # deprecated
     BootContent,
@@ -250,6 +251,16 @@ def test_prepare_userspace_for_initram(monkeypatch, adjust_cwd, input_msgs, pkgs
     assert _sort_files(upgradeinitramfsgenerator._copy_files.args[1]) == _files
 
 
+class MockedGetFspace(object):
+    def __init__(self, space):
+        self.space = space
+
+    def __call__(self, dummy_path, convert_to_mibs=False):
+        if not convert_to_mibs:
+            return self.space
+        return int(self.space / 1024 / 1024)  # noqa: W1619; pylint: disable=old-division
+
+
 @pytest.mark.parametrize('input_msgs,dracut_modules,kernel_modules', [
     # test dracut modules with UpgradeDracutModule(s) - orig functionality
     (gen_UDM_list(MODULES[0]), MODULES[0], []),
@@ -275,8 +286,11 @@ def test_generate_initram_disk(monkeypatch, input_msgs, dracut_modules, kernel_m
     monkeypatch.setattr(upgradeinitramfsgenerator, '_get_target_kernel_version', lambda _: '')
     monkeypatch.setattr(upgradeinitramfsgenerator, 'copy_kernel_modules', MockedCopyArgs())
     monkeypatch.setattr(upgradeinitramfsgenerator, 'copy_boot_files', lambda dummy: None)
+    monkeypatch.setattr(upgradeinitramfsgenerator, '_get_fspace', MockedGetFspace(2*2**30))
     upgradeinitramfsgenerator.generate_initram_disk(context)
 
+    # TODO(pstodulk): add tests for the check of the free space (sep. from this func)
+
     # test now just that all modules have been passed for copying - so we know
     # all modules have been consumed
     detected_dracut_modules = set()