Executor: start log streaming before connection and logging setup

Some python logging handlers (eg, splunk) may start background
threads which are not going to survive the fork for the console
log stream process.  To mitigate this, start the log streamer
before the logging setup, and execute logging setup in both
processes.

Change-Id: I3fe4b0fdfed0e307fe9436a8980f8ea58eda9070

zuul/cmd/executor.py

@@ -62,6 +62,9 @@ class Executor(zuul.cmd.ZuulDaemonApp):
             os.close(pipe_write)
             import zuul.lib.log_streamer
 
+            self.setup_logging('executor', 'log_config')
+            self.log = logging.getLogger("zuul.Executor")
+
             self.log.info("Starting log streamer")
             streamer = zuul.lib.log_streamer.LogStreamer(
                 '::', self.finger_port, self.job_dir)
@@ -110,16 +113,6 @@ class Executor(zuul.cmd.ZuulDaemonApp):
         if user:
             self.dropPrivs(user)
 
-        self.setup_logging('executor', 'log_config')
-        self.log = logging.getLogger("zuul.Executor")
-
-        self.configure_connections(sources=True)
-
-        # Check bwrap after dropping privileges
-        self.connections.drivers['bubblewrap'].setCgroupManager(
-            cgroup_manager)
-        self.connections.drivers['bubblewrap'].check()
-
         if self.config.has_option('executor', 'job_dir'):
             self.job_dir = os.path.expanduser(
                 self.config.get('executor', 'job_dir'))
@@ -137,8 +130,20 @@ class Executor(zuul.cmd.ZuulDaemonApp):
                         zuul.executor.server.DEFAULT_FINGER_PORT)
         )
 
+        # This forks, so minimize setup before this point.  Do not set
+        # up logging since some log handlers may start threads.
         self.start_log_streamer()
 
+        self.setup_logging('executor', 'log_config')
+        self.log = logging.getLogger("zuul.Executor")
+
+        self.configure_connections(sources=True)
+
+        # Check bwrap after dropping privileges
+        self.connections.drivers['bubblewrap'].setCgroupManager(
+            cgroup_manager)
+        self.connections.drivers['bubblewrap'].check()
+
         ExecutorServer = zuul.executor.server.ExecutorServer
         self.executor = ExecutorServer(self.config,
                                        self.connections,