check_ceph_libs_mk: Various fixes

* Bugs in python-psutil
  Need to upgrade to package from jessie-backports in order
  to address the following issues:
    giampaolo/psutil#522
    giampaolo/psutil#572

* Race when checking for processes
  It seems that is possible to query for a process that no longer
  exists. Handle that situation by ignoring it.

* Wrong message when no processes are matches
  Not a problem at all, but handle that situation by printing a
  different message, just to be clear.

* Filter out qemu-system-x86_64 processes that do not have Ceph disks
  For some reason, it seems that QEMU maps librados and librbd
  libraries even when not using them (ie NFS, DRBD). Add a function
  that parses the cmdline of each QEMU process, looks for disk drives,
  and by looking at the path, tells if we should check that process or
  not. Only check VMs with rbd and tapdev (Archipelago) disks.

Also, split out process filtering stuff to a separate function.

monitoring/checkmk/check_ceph_libs_mk

@@ -38,6 +38,8 @@ import psutil
 import sys
 import argparse
 import json
+import re
+import os
 
 CHECK_NAME = 'check_ceph_libs'
 
@@ -71,15 +73,59 @@ def check_result(msg, status):
     sys.exit(0)
 
 
+def check_qemu_process(cmdline):
+    """
+    An ugly function to determine if a QEMU process needs to be checked or not
+
+    Only check QEMU instances with rbd or archipelago disks
+    """
+    ret = False
+
+    regex = re.compile(r'-drive file=([\d\w\-\.:/]+)')
+    results = regex.findall(' '.join(cmdline))
+    if results:
+        for disk in results:
+            if 'rbd' in disk:
+                ret = True
+            else:
+                if os.path.exists(disk):
+                    if 'tapdev' in os.path.realpath(disk):
+                        ret = True
+
+    return ret
+
+
+def check_process(proc, procs_to_check):
+    """
+    Determine if a given process should be checked or not
+
+    GRNET-specific rules in this function
+    """
+    check_proc = False
+    if any(x in proc['name'] for x in procs_to_check):
+        if proc['name'] == 'qemu-system-x86_64':
+            if check_qemu_process(proc['cmdline']):
+                check_proc = True
+        else:
+            check_proc = True
+
+    return check_proc
+
+
 def fetch_procs(procs_to_check):
     """
     Fetch all processes with name that matches entries in procs_to_check
     """
-    procs = [
-        p.as_dict()
-        for p in psutil.process_iter()
-        if any(x in p.as_dict()['name'] for x in 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.
+        try:
+            _pinfo = p.as_dict()
+        except psutil.NoSuchProcess:
+            continue
+        if check_process(_pinfo, procs_to_check):
+            procs.append(_pinfo)
 
     return procs
 
@@ -150,6 +196,8 @@ def main():
     try:
         # Fetch all processes using ceph-related libraries
         procs = fetch_procs(PROCS_TO_CHECK)
+        if not procs:
+            check_result('No processes matches on node', 'OK')
 
         # Find processes running old libraries
         procs_old_libs = find_procs_old_libs(procs, LIBS_TO_CHECK)
@@ -164,7 +212,7 @@ def main():
                 check_result('{} processes running with old Ceph libraries.'
                              .format(len(procs_old_libs['processes'])), 'WARNING')
             else:
-                check_result('All processes are running latest installed libs', 'OK')
+                check_result('All processes are running the latest installed libs', 'OK')
 
     except Exception as e:
         check_result('Something went wrong: {}'.format(str(e)), 'UNKNOWN')