[pacemaker] Redesign node enumeration logic

It has been found that `pcs status` output is liable to change, which
ends up breaking our parsing of node lists when using it on newer
versions.

Instead, first try to parse through `crm_mon` output, which is what `pcs
status` uses under the hood, but as a stable and reliable xml format.

Failing that, for example if the `--primary` node is not functioning as
part of the cluster, source `/etc/corosync/corosync.conf` instead.

Related: RHBZ2065805
Related: RHBZ2065811

Signed-off-by: Jake Hunsaker <jhunsake@redhat.com>

1 files changed, 76 insertions, 34 deletions

diff --git a/sos/collector/clusters/pacemaker.py b/sos/collector/clusters/pacemaker.py
index 55024314..49d0ce51 100644
--- a/sos/collector/clusters/pacemaker.py
+++ b/sos/collector/clusters/pacemaker.py
@@ -8,7 +8,11 @@
 #
 # See the LICENSE file in the source distribution for further information.
 
+import re
+
 from sos.collector.clusters import Cluster
+from setuptools._vendor.packaging import version
+from xml.etree import ElementTree
 
 
 class pacemaker(Cluster):
@@ -18,42 +22,80 @@ class pacemaker(Cluster):
     packages = ('pacemaker',)
     option_list = [
         ('online', True, 'Collect nodes listed as online'),
-        ('offline', True, 'Collect nodes listed as offline')
+        ('offline', True, 'Collect nodes listed as offline'),
+        ('only-corosync', False, 'Only use corosync.conf to enumerate nodes')
     ]
 
     def get_nodes(self):
-        self.res = self.exec_primary_cmd('pcs status')
-        if self.res['status'] != 0:
-            self.log_error('Cluster status could not be determined. Is the '
-                           'cluster running on this node?')
-            return []
-        if 'node names do not match' in self.res['output']:
-            self.log_warn('Warning: node name mismatch reported. Attempts to '
-                          'connect to some nodes may fail.\n')
-        return self.parse_pcs_output()
-
-    def parse_pcs_output(self):
-        nodes = []
-        if self.get_option('online'):
-            nodes += self.get_online_nodes()
-        if self.get_option('offline'):
-            nodes += self.get_offline_nodes()
-        return nodes
-
-    def get_online_nodes(self):
-        for line in self.res['output'].splitlines():
-            if line.startswith('Online:'):
-                nodes = line.split('[')[1].split(']')[0]
-                return [n for n in nodes.split(' ') if n]
-
-    def get_offline_nodes(self):
-        offline = []
-        for line in self.res['output'].splitlines():
-            if line.startswith('Node') and line.endswith('(offline)'):
-                offline.append(line.split()[1].replace(':', ''))
-            if line.startswith('OFFLINE:'):
-                nodes = line.split('[')[1].split(']')[0]
-                offline.extend([n for n in nodes.split(' ') if n])
-        return offline
+        self.nodes = []
+        # try crm_mon first
+        try:
+            if not self.get_option('only-corosync'):
+                try:
+                    self.get_nodes_from_crm()
+                except Exception as err:
+                    self.log_warn("Falling back to sourcing corosync.conf. "
+                                  "Could not parse crm_mon output: %s" % err)
+            if not self.nodes:
+                # fallback to corosync.conf, in case the node we're inspecting
+                # is offline from the cluster
+                self.get_nodes_from_corosync()
+        except Exception as err:
+            self.log_error("Could not determine nodes from cluster: %s" % err)
+
+        _shorts = [n for n in self.nodes if '.' not in n]
+        if _shorts:
+            self.log_warn(
+                "WARNING: Node addresses '%s' may not resolve locally if you "
+                "are not running on a node in the cluster. Try using option "
+                "'-c pacemaker.only-corosync' if these connections fail."
+                % ','.join(_shorts)
+            )
+        return self.nodes
+
+    def get_nodes_from_crm(self):
+        """
+        Try to parse crm_mon output for node list and status.
+        """
+        xmlopt = '--output-as=xml'
+        # older pacemaker had a different option for xml output
+        _ver = self.exec_primary_cmd('crm_mon --version')
+        if _ver['status'] == 0:
+            cver = _ver['output'].split()[1].split('-')[0]
+            if not version.parse(cver) > version.parse('2.0.3'):
+                xmlopt = '--as-xml'
+        else:
+            return
+        _out = self.exec_primary_cmd(
+            "crm_mon --one-shot --inactive %s" % xmlopt,
+            need_root=True
+        )
+        if _out['status'] == 0:
+            self.parse_crm_xml(_out['output'])
+
+    def parse_crm_xml(self, xmlstring):
+        """
+        Parse the xml output string provided by crm_mon
+        """
+        _xml = ElementTree.fromstring(xmlstring)
+        nodes = _xml.find('nodes')
+        for node in nodes:
+            _node = node.attrib
+            if self.get_option('online') and _node['online'] == 'true':
+                self.nodes.append(_node['name'])
+            elif self.get_option('offline') and _node['online'] == 'false':
+                self.nodes.append(_node['name'])
+
+    def get_nodes_from_corosync(self):
+        """
+        As a fallback measure, read corosync.conf to get the node list. Note
+        that this prevents us from separating online nodes from offline nodes.
+        """
+        self.log_warn("WARNING: unable to distinguish online nodes from "
+                      "offline nodes when sourcing from corosync.conf")
+        cc = self.primary.read_file('/etc/corosync/corosync.conf')
+        nodes = re.findall(r'((\sring0_addr:)(.*))', cc)
+        for node in nodes:
+            self.nodes.append(node[-1].strip())
 
 # vim: set et ts=4 sw=4 :