check_ceph_libs_mk: Handle some failures

There are cases where this check fails. Let's take care of them:
* KeyError: 'getpwuid(): uid not found: XXXXX'
 This seems to be caused by a bug in grnet/nss-uidpool.

* IOError: 'No such file or directory: '/proc/XXXXX/maps'
  This case happens when the check queries for a PID that does not
  exist anymore.

monitoring/checkmk/check_ceph_libs_mk

@@ -114,12 +114,15 @@ def fetch_procs(procs_to_check):
     """
     procs = []
     for p in psutil.process_iter():
-        # It is possible that a process found by process_iter() has died.
-        # Catch that exception and ignore it.
+        # It is possible that:
+        # * a process found by process_iter() has died
+        # * a UID cannot be found (see libnss-uidpool bug, T1934)
+        # Catch these exceptions and ignore them.
         try:
             _pinfo = p.as_dict()
-        except psutil.NoSuchProcess:
+        except (psutil.NoSuchProcess, KeyError):
             continue
+
         if check_process(_pinfo, procs_to_check):
             procs.append(_pinfo)
 
@@ -155,12 +158,18 @@ def find_procs_old_libs(procs, libs_to_check):
         # Since psutil 4.0.0, '(deleted)' string gets deleted.
         # There is no way in psutil to find out if the library has
         # been deleted, other than reading the /proc/[pid]/maps file.
-        mapfile = '/proc/{}/maps'.format(proc['pid'])
-        with open(mapfile, 'r') as f:
-            for line in f:
-                if any(lib in line for lib in libs_to_check):
-                    if '(deleted)' in line:
-                        oldmaps.append(' '.join(line.split()[-2:]))
+        try:
+            mapfile = '/proc/{}/maps'.format(proc['pid'])
+            with open(mapfile, 'r') as f:
+                for line in f:
+                    if any(lib in line for lib in libs_to_check):
+                        if '(deleted)' in line:
+                            oldmaps.append(' '.join(line.split()[-2:]))
+        # In case a process found by fetch_procs() has died, its mapfile in
+        # procfs won't be available. We do not want the check to fail, so
+        # handle that exception accordingly.
+        except IOError:
+            continue
 
         # If oldmaps contains at least one element, we have to show it.
         # Append a dict with all proc information and stale mappings. We pass