tracer: add logging about tracing events and errors

sipssert/scenario.py

@@ -55,7 +55,7 @@ def __init__(self, scenario_file, controller, test_set, set_logs_dir, set_defaul
         nets = self.networks if self.networks else []
         if self.network:
             nets.append(self.network)
-        self.tracer = tracer.Tracer(self.scen_logs_dir, "capture", nets)
+        self.tracer = tracer.Tracer(self.scen_logs_dir, "capture", nets, self.name)
         self.timeout = self.config.get("timeout", 0)
         container_prefix = f"{test_set.name}/{self.name}"
         self.tasks = tasks_list.TasksList("tasks", self.dirname, self.scen_logs_dir,

sipssert/tracer.py

@@ -24,37 +24,60 @@
 import os
 import time
 import subprocess
+from sipssert import logger
 
 class Tracer():
 
     """Class that implements the network capturing"""
 
-    def __init__(self, directory, name, net=[]):
+    def __init__(self, directory, filename, net=[], name=None):
         # TODO: use tshark instead of tcpdump
         if len(net) == 0 or (len(net) == 1 and net == "host") or len(net) > 1:
             self.interface = "any"
         else:
             self.interface = net[0]
-        self.capture_file = os.path.join(directory, f"{name}.pcap")
+        self.name = name if name else filename
+        self.capture_file = os.path.join(directory, f"{filename}.pcap")
         self.process = None
 
+    def status(self):
+        if not self.process:
+            return None, None
+        rc = self.process.returncode
+        if rc and rc != 0:
+            ret = self.process.communicate()[1]
+            if ret:
+                ret = ret.decode('utf-8')
+        else:
+            ret = None
+        return rc, ret
+
     def stop(self):
         """Stops started tcpdump"""
         if not self.process:
             return
         self.process.terminate()
         self.process.wait()
+        rc, err = self.status()
         self.process = None
+        logger.slog.debug(f"stopped tracer for {self.name}")
+        if rc and rc != 0:
+            logger.slog.error(f"tracer {self.name} failed with ({rc}):\n{err}")
 
     def start(self):
         """Starts a tcpdump for a scenario"""
         self.process = subprocess.Popen(['tcpdump',
             '-i', self.interface,
             '-w', self.capture_file],
             stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL)
-        # wait for proc to start
-        time.sleep(0.5)
+            stderr=subprocess.PIPE)
+        rc, err = self.status()
+        if rc and rc != 0:
+            logger.slog.error(f"could not start tracer {self.name} ({rc}):\n{err}")
+            # wait for proc to start
+        else:
+            logger.slog.debug(f"started tracer for {self.name}")
+            time.sleep(0.5)
 
 
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