Handle detect strings as arguments for blockdevs

Allows specifying blockdevs in the OSD and OSD-DB addition commands as
detect strings rather than actual block device paths. This provides
greater flexibility for automation with pvcbootstrapd (which originates
the concept of detect strings) and in general usage as well.

node-daemon/pvcnoded/objects/CephInstance.py

@@ -26,7 +26,76 @@ import psutil
 import daemon_lib.common as common
 
 from distutils.util import strtobool
-from re import search
+from re import search, match, sub
+
+
+def get_detect_device(detect_string):
+    """
+    Parses a "detect:" string into a normalized block device path using lsscsi.
+
+    A detect string is formatted "detect:<NAME>:<SIZE>:<ID>", where
+    NAME is some unique identifier in lsscsi, SIZE is a human-readable
+    size value to within +/- 3% of the real size of the device, and
+    ID is the Nth (0-indexed) matching entry of that NAME and SIZE.
+    """
+    _, name, size, idd = detect_string.split(":")
+    if _ != "detect":
+        return None
+
+    retcode, stdout, stderr = common.run_os_command("lsscsi -s")
+    if retcode:
+        print(f"Failed to run lsscsi: {stderr}")
+        return None
+
+    # Get valid lines
+    lsscsi_lines_raw = stdout.split("\n")
+    lsscsi_lines = list()
+    for line in lsscsi_lines_raw:
+        if not line:
+            continue
+        split_line = line.split()
+        if split_line[1] != "disk":
+            continue
+        lsscsi_lines.append(line)
+
+    # Handle size determination (+/- 3%)
+    lsscsi_sizes = set()
+    for line in lsscsi_lines:
+        lsscsi_sizes.add(split_line[-1])
+    for l_size in lsscsi_sizes:
+        b_size = float(sub(r"\D.", "", size))
+        t_size = float(sub(r"\D.", "", l_size))
+
+        plusthreepct = t_size * 1.03
+        minusthreepct = t_size * 0.97
+
+        if b_size > minusthreepct and b_size < plusthreepct:
+            size = l_size
+            break
+
+    blockdev = None
+    matches = list()
+    for idx, line in enumerate(lsscsi_lines):
+        # Skip non-disk entries
+        if line.split()[1] != "disk":
+            continue
+        # Skip if name is not contained in the line (case-insensitive)
+        if name.lower() not in line.lower():
+            continue
+        # Skip if the size does not match
+        if size != line.split()[-1]:
+            continue
+        # Get our blockdev and append to the list
+        matches.append(line.split()[-2])
+
+    blockdev = None
+    # Find the blockdev at index {idd}
+    for idx, _blockdev in enumerate(matches):
+        if int(idx) == int(idd):
+            blockdev = _blockdev
+            break
+
+    return blockdev
 
 
 class CephOSDInstance(object):
@@ -76,6 +145,22 @@ class CephOSDInstance(object):
     def add_osd(
         zkhandler, logger, node, device, weight, ext_db_flag=False, ext_db_ratio=0.05
     ):
+        # Handle a detect device if that is passed
+        if match(r"detect:", device):
+            ddevice = get_detect_device(device)
+            if ddevice is None:
+                logger.out(
+                    f"Failed to determine block device from detect string {device}",
+                    state="e",
+                )
+                return False
+            else:
+                logger.out(
+                    f"Determined block device {ddevice} from detect string {device}",
+                    state="i",
+                )
+                device = ddevice
+
         # We are ready to create a new OSD on this node
         logger.out("Creating new OSD disk on block device {}".format(device), state="i")
         try:
@@ -354,17 +439,33 @@ class CephOSDInstance(object):
 
     @staticmethod
     def add_db_vg(zkhandler, logger, device):
+        # Check if an existsing volume group exists
+        retcode, stdout, stderr = common.run_os_command("vgdisplay osd-db")
+        if retcode != 5:
+            logger.out('Ceph OSD database VG "osd-db" already exists', state="e")
+            return False
+
+        # Handle a detect device if that is passed
+        if match(r"detect:", device):
+            ddevice = get_detect_device(device)
+            if ddevice is None:
+                logger.out(
+                    f"Failed to determine block device from detect string {device}",
+                    state="e",
+                )
+                return False
+            else:
+                logger.out(
+                    f"Determined block device {ddevice} from detect string {device}",
+                    state="i",
+                )
+                device = ddevice
+
         logger.out(
             "Creating new OSD database volume group on block device {}".format(device),
             state="i",
         )
         try:
-            # 0. Check if an existsing volume group exists
-            retcode, stdout, stderr = common.run_os_command("vgdisplay osd-db")
-            if retcode != 5:
-                logger.out('Ceph OSD database VG "osd-db" already exists', state="e")
-                return False
-
             # 1. Create an empty partition table
             logger.out(
                 "Creating partitions on block device {}".format(device), state="i"