Register term_handler for all zuul apps

Almost all zuul apps use the method term_handler for SIGINT and
SIGTERM. Defining this centrally in ZuulDaemonApp makes this much
simpler and without repitition.

Change-Id: I68f8d1bf52b0e16340818d2bcc44cd9fc5868ca7

zuul/cmd/__init__.py

@@ -170,6 +170,14 @@ class ZuulDaemonApp(ZuulApp, metaclass=abc.ABCMeta):
                              expand_user=True)
         return pid_fn
 
+    @abc.abstractmethod
+    def exit_handler(self, signum, frame):
+        """
+        This is a signal handler which is called on SIGINT and SIGTERM and must
+        take care of stopping the application.
+        """
+        pass
+
     @abc.abstractmethod
     def run(self):
         """
@@ -189,6 +197,8 @@ class ZuulDaemonApp(ZuulApp, metaclass=abc.ABCMeta):
         signal.signal(signal.SIGUSR2, stack_dump_handler)
 
         if self.args.nodaemon:
+            signal.signal(signal.SIGTERM, self.exit_handler)
+            signal.signal(signal.SIGINT, self.exit_handler)
             self.run()
         else:
             # Exercise the pidfile before we do anything else (including

zuul/cmd/executor.py

@@ -19,7 +19,6 @@ import logging
 import os
 import pwd
 import sys
-import signal
 import tempfile
 
 import zuul.cmd
@@ -53,8 +52,6 @@ class Executor(zuul.cmd.ZuulDaemonApp):
 
     def exit_handler(self, signum, frame):
         self.executor.stop()
-        self.executor.join()
-        sys.exit(0)
 
     def start_log_streamer(self):
         pipe_read, pipe_write = os.pipe()
@@ -130,16 +127,7 @@ class Executor(zuul.cmd.ZuulDaemonApp):
                                        log_streaming_port=self.finger_port)
         self.executor.start()
 
-        if self.args.nodaemon:
-            signal.signal(signal.SIGTERM, self.exit_handler)
-            while True:
-                try:
-                    signal.pause()
-                except KeyboardInterrupt:
-                    print("Ctrl + C: asking executor to exit nicely...\n")
-                    self.exit_handler(signal.SIGINT, None)
-        else:
-            self.executor.join()
+        self.executor.join()
 
 
 def main():

zuul/cmd/fingergw.py

@@ -14,7 +14,6 @@
 # under the License.
 
 import logging
-import signal
 import sys
 
 import zuul.cmd
@@ -47,6 +46,9 @@ class FingerGatewayApp(zuul.cmd.ZuulDaemonApp):
         if self.args.command:
             self.args.nodaemon = True
 
+    def exit_handler(self, signum, frame):
+        self.stop()
+
     def run(self):
         '''
         Main entry point for the FingerGatewayApp.
@@ -84,19 +86,7 @@ class FingerGatewayApp(zuul.cmd.ZuulDaemonApp):
         self.log.info('Starting Zuul finger gateway app')
         self.gateway.start()
 
-        if self.args.nodaemon:
-            # NOTE(Shrews): When running in non-daemon mode, although sending
-            # the 'stop' command via the command socket will shutdown the
-            # gateway, it's still necessary to Ctrl+C to stop the app.
-            while True:
-                try:
-                    signal.pause()
-                except KeyboardInterrupt:
-                    print("Ctrl + C: asking gateway to exit nicely...\n")
-                    self.stop()
-                    break
-        else:
-            self.gateway.wait()
+        self.gateway.wait()
 
         self.log.info('Stopped Zuul finger gateway app')
 

zuul/cmd/merger.py

@@ -14,7 +14,6 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-import signal
 import sys
 
 import zuul.cmd
@@ -44,8 +43,6 @@ class Merger(zuul.cmd.ZuulDaemonApp):
 
     def exit_handler(self, signum, frame):
         self.merger.stop()
-        self.merger.join()
-        sys.exit(0)
 
     def run(self):
         # See comment at top of file about zuul imports
@@ -62,16 +59,7 @@ class Merger(zuul.cmd.ZuulDaemonApp):
                                                      self.connections)
         self.merger.start()
 
-        if self.args.nodaemon:
-            signal.signal(signal.SIGTERM, self.exit_handler)
-            while True:
-                try:
-                    signal.pause()
-                except KeyboardInterrupt:
-                    print("Ctrl + C: asking merger to exit nicely...\n")
-                    self.exit_handler(signal.SIGINT, None)
-        else:
-            self.merger.join()
+        self.merger.join()
 
 
 def main():

zuul/cmd/scheduler.py

@@ -63,9 +63,7 @@ class Scheduler(zuul.cmd.ZuulDaemonApp):
 
     def exit_handler(self, signum, frame):
         self.sched.exit()
-        self.sched.join()
         self.stop_gear_server()
-        sys.exit(0)
 
     def start_gear_server(self):
         pipe_read, pipe_write = os.pipe()
@@ -175,16 +173,7 @@ class Scheduler(zuul.cmd.ZuulDaemonApp):
 
         signal.signal(signal.SIGHUP, self.reconfigure_handler)
 
-        if self.args.nodaemon:
-            signal.signal(signal.SIGTERM, self.exit_handler)
-            while True:
-                try:
-                    signal.pause()
-                except KeyboardInterrupt:
-                    print("Ctrl + C: asking scheduler to exit nicely...\n")
-                    self.exit_handler(signal.SIGINT, None)
-        else:
-            self.sched.join()
+        self.sched.join()
 
 
 def main():

zuul/cmd/web.py

@@ -89,12 +89,6 @@ class WebServer(zuul.cmd.ZuulDaemonApp):
                                        name='web')
         self.thread.start()
 
-        try:
-            signal.pause()
-        except KeyboardInterrupt:
-            print("Ctrl + C: asking web server to exit nicely...\n")
-            self.exit_handler(signal.SIGINT, None)
-
         self.thread.join()
         loop.stop()
         loop.close()