Workaround: LVM can't detect VG by UUID and vgcfgrestore fails to construct volume group even though blkid shows the correct UUID

lvm.conf

#
# This is a boilerplate LVM configuration file (/etc/lvm/lvm.conf) with a few simple modifications
# that will fix a bug encountered when booting a no-modules kernel with LVM inside of a LUKS device
# The bug is best described as a failure of LVM to find a disk by UUID, even though the device with
# that UUID is present (in this case, in the form of an unlocked LUKS volume)
#
##
# Symptoms/Preconditions:
#  - LUKS device is unlocked and the UUID for the VG can be seen in the `blkid` output
#  - The LVM VGs are not present in /dev/mapper/ as expected
#  - Using pvscan, lvscan, vgscan and vgchange -ay have no effect
#  - Using vgcfgrestore with the backup file defining the configuration of the VG (explicitly!)
#    fails, saying it can't find the UUID for the PV
#  - The PV UUID is present in `blkid` output, suggesting LVM is searching using some alternate
#    method to find the PV by UUID
#
## Cause
#   I honestly do not know. This may be something related to udev, as I believe the LVM tools in
#   the default configuration rely on UUID information from udev. As this behavior was only
#   encountered on a custom built kernel with modules disabled, there is a strong likelihood that
#   this has *something* to do with the problem- but the solution doesn't seem to have anything to do
#   with missing kernel features.. ???
#   EDIT: Cause seems likely to be a lack of a running lvmetad .. 
#
# Solution/Workaround:
#
# The important changes are in the scan and filter lines. Once the lvm.conf is changed to include the
# added regex patterns, the lvm tools are able to discover the UUID correctly. Once the lvm.conf file
# is updated, it is possible to use all of the standard commands to activate the VG..
#
# lvm pvscan
# lvm lvscan
# lvm vgscan --mknodes
# vgchange -ay
#
# Probably the following will be all that you need (if you have a VG backup file)
# vgcfgrestore -f /etc/lvm/backup/<my>-vg <my>-vg
# cgchange -ay
#
config {
	checks = 1
	abort_on_errors = 0
	profile_dir = "/etc/lvm/profile"
}

devices {
	dir = "/dev"
	scan = [ "/dev", "/dev/mapper" ]
	obtain_device_list_from_udev = 1
	external_device_info_source = "none"
	filter = [ "a|/dev/sda.*|", "a|/dev/mapper/.*|", "a|/dev/disk/by-uuid/.*|", "a|/dev/disk/by-id/dm-uuid-.*mpath-.*|", "r|.*|"]
	sysfs_scan = 1
	scan_lvs = 1
	multipath_component_detection = 1
	md_component_detection = 1
	fw_raid_component_detection = 0
	md_chunk_alignment = 1
	data_alignment_detection = 1
	data_alignment = 0
	data_alignment_offset_detection = 1
	ignore_suspended_devices = 0
	ignore_lvm_mirrors = 1
	require_restorefile_with_uuid = 1
	pv_min_size = 2048
	issue_discards = 0
	allow_changes_with_duplicate_pvs = 0
}

allocation {
	maximise_cling = 1
	use_blkid_wiping = 1
	wipe_signatures_when_zeroing_new_lvs = 1
	mirror_logs_require_separate_pvs = 0
	cache_pool_metadata_require_separate_pvs = 0
	thin_pool_metadata_require_separate_pvs = 0
}

log {
	verbose = 0
	silent = 0
	syslog = 1
	overwrite = 0
	level = 0
	indent = 1
	command_names = 0
	prefix = "  "
	activation = 0
	debug_classes = [ "memory", "devices", "io", "activation", "allocation", "metadata", "cache", "locking", "lvmpolld", "dbus" ]
}

backup {
	backup = 1
	backup_dir = "/etc/lvm/backup"
	archive = 1
	archive_dir = "/etc/lvm/archive"
	retain_min = 10
	retain_days = 30
}

shell {
	history_size = 100
}

global {
	umask = 077
	test = 0
	units = "r"
	si_unit_consistency = 1
	suffix = 1
	activation = 1
	proc = "/proc"
	etc = "/etc"
	wait_for_locks = 1
	locking_dir = "/run/lock/lvm"
	prioritise_write_locks = 1
	abort_on_internal_errors = 0
	metadata_read_only = 0
	mirror_segtype_default = "raid1"
	raid10_segtype_default = "raid10"
	sparse_segtype_default = "thin"
	event_activation = 1
	use_lvmlockd = 0
	system_id_source = "none"
	use_lvmpolld = 1
	notify_dbus = 1
}

activation {
	checks = 0
	udev_sync = 1
	udev_rules = 1
	verify_udev_operations = 0
	retry_deactivation = 1
	missing_stripe_filler = "error"
	use_linear_target = 1
	reserved_stack = 64
	reserved_memory = 8192
	process_priority = -18
	raid_region_size = 2048
	readahead = "auto"
	raid_fault_policy = "warn"
	mirror_image_fault_policy = "remove"
	mirror_log_fault_policy = "allocate"
	snapshot_autoextend_threshold = 100
	snapshot_autoextend_percent = 20
	thin_pool_autoextend_threshold = 100
	thin_pool_autoextend_percent = 20
	vdo_pool_autoextend_threshold = 100
	use_mlockall = 0
	monitoring = 1
	polling_interval = 15
	activation_mode = "degraded"
}

dmeventd {
	mirror_library = "libdevmapper-event-lvm2mirror.so"
	snapshot_library = "libdevmapper-event-lvm2snapshot.so"
	thin_library = "libdevmapper-event-lvm2thin.so"
}