cephadm: use importlib.metadata for querying ceph_iscsi's version

use importlib.metadata for querying ceph_iscsi's version and fallback to
pkg_resources. as the former is only available in Python 3.8, while
the latter is deprecated.

Refs https://tracker.ceph.com/issues/66201
Signed-off-by: Kefu Chai <tchaikov@gmail.com>
(cherry picked from commit cbd4bede7f258823462f27cb15d86e13eb52c359)

Conflicts:
	src/cephadm/cephadmlib/daemons/iscsi.py [ this file doesn't
	  exist in quincy, get_version() lives in src/cephadm/cephadm ]

diff --git a/src/cephadm/cephadm b/src/cephadm/cephadm
index 6c64a8b6d7fb03c4fe81b407d39f3cfa52925602..2addee773e345a7781baafcd8675966cf7e511ab 100755 (executable)
--- a/src/cephadm/cephadm
+++ b/src/cephadm/cephadm
@@ -892,6 +892,11 @@ class CephIscsi(object):
         out, _, code = python(
             "from importlib.metadata import version; print(version('ceph_iscsi'))"
         )
+        if code == 0:
+            return out.strip()
+        out, _, code = python(
+            "import pkg_resources; print(pkg_resources.require('ceph_iscsi')[0].version)"
+        )
         if code == 0:
             return out.strip()
         return None