Use journald for kernlogs if kern.log not found

On some hosts or sosreports kern.log may be missing so we
fall back to journald for calltrace checking if this is the
case.

hotsos/core/host_helpers/cli/cli.py

@@ -64,6 +64,9 @@ def __init__(self, *args, **kwargs):
 
     def format_journalctl_cmd(self, **kwargs):
         """ Add optional extras to journalctl command. """
+        if kwargs.get("opts"):
+            self.cmd = f"{self.cmd} {kwargs.get('opts')}"
+
         if kwargs.get("unit"):
             self.cmd = f"{self.cmd} --unit {kwargs.get('unit')}"
 
@@ -84,7 +87,13 @@ def __init__(self, *args, **kwargs):
         self.register_hook("pre-exec", self.preformat_sos_journalctl)
 
     def preformat_sos_journalctl(self, **kwargs):
-        self.path = f"journalctl -oshort-iso -D {self.path}"
+        default_opts = '-oshort-iso'
+        if kwargs.get("opts"):
+            self.path = (f"journalctl {default_opts} {kwargs.get('opts')} "
+                         f"-D {self.path}")
+        else:
+            self.path = f"journalctl {default_opts} -D {self.path}"
+
         if kwargs.get("unit"):
             self.path = f"{self.path} --unit {kwargs.get('unit')}"
 

hotsos/core/plugins/kernel/kernlog/calltrace.py

@@ -483,10 +483,8 @@ def __init__(self, *args, **kwargs):
         self.run()
 
     def run(self):
-        for tracetype in self.tracetypes:
-            self.searcher.add(tracetype.searchdef, self.path)
-
-        self.results = self.searcher.run()
+        self.results = self.perform_search([t.searchdef
+                                            for t in self.tracetypes])
         for tracetype in self.tracetypes:
             if isinstance(tracetype.searchdef, SequenceSearchDef):
                 results = self.results.find_sequence_sections(

hotsos/core/plugins/kernel/kernlog/common.py

@@ -2,7 +2,11 @@
 import os
 
 from hotsos.core.config import HotSOSConfig
-from hotsos.core.host_helpers import CLIHelper, HostNetworkingHelper
+from hotsos.core.host_helpers import (
+    CLIHelper,
+    CLIHelperFile,
+    HostNetworkingHelper,
+)
 from hotsos.core.search import (
     CommonTimestampMatcher,
     FileSearcher,
@@ -86,6 +90,21 @@ def __iter__(self):
 class KernLogBase():
     """ Base class for kernlog analysis implementations. """
     def __init__(self):
+        self.hostnet_helper = HostNetworkingHelper()
+        self.cli_helper = CLIHelper()
+
+    @property
+    def path(self):
+        """
+        Return path we want to search. By default we search kern.log but that
+        may not exist e.g. sosreport does not collect it if systemd-journald is
+        running. In that case we need to fallback to using the journal.
+
+        @return: path
+        """
+        return os.path.join(HotSOSConfig.data_root, 'var/log/kern.log')
+
+    def perform_search(self, searchdefs):
         try:
             constraint = SearchConstraintSearchSince(
                                          ts_matcher_cls=CommonTimestampMatcher)
@@ -94,14 +113,17 @@ def __init__(self):
                         "calltrace checker: %s", exc)
             constraint = None
 
-        self.searcher = FileSearcher(constraint=constraint)
-        self.hostnet_helper = HostNetworkingHelper()
-        self.cli_helper = CLIHelper()
+        searcher = FileSearcher(constraint=constraint)
+        with CLIHelperFile() as cli:
+            if not os.path.exists(self.path):
+                path = cli.journalctl(opts='-k')
+            else:
+                if HotSOSConfig.use_all_logs:
+                    path = f"{self.path}*"
+                else:
+                    path = self.path
 
-    @property
-    def path(self):
-        path = os.path.join(HotSOSConfig.data_root, 'var/log/kern.log')
-        if HotSOSConfig.use_all_logs:
-            return f"{path}*"
+            for sd in searchdefs:
+                searcher.add(sd, path)
 
-        return path
+            return searcher.run()

hotsos/core/plugins/kernel/kernlog/events.py

@@ -7,10 +7,8 @@ class KernLogEvents(KernLogBase):
     """ Kern log events info. """
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        for event in [self.over_mtu_dropped_packets_search_def]:
-            self.searcher.add(event, self.path)
-
-        self.results = self.searcher.run()
+        self.results = self.perform_search([
+                                     self.over_mtu_dropped_packets_search_def])
 
     @property
     def over_mtu_dropped_packets_search_def(self):