Revert "Add graceful stop environment variable"

This reverts commit f1fca03fd1.

This needs more discussion.

Change-Id: Iebf5c01e4436899a9d6e37150337dcdb4cf9705f

doc/source/discussion/components.rst

@@ -927,12 +927,6 @@ circumstances this will be the best way to stop Zuul.
 To stop the executor immediately, run ``zuul-executor stop``. Jobs that were
 running on the stopped executor will be rescheduled on other executors.
 
-The executor normally responds to a ``SIGTERM`` signal in the same way
-as the ``stop`` command, however you can change this behavior to match
-``graceful`` by setting the environment variable
-``ZUUL_EXECUTOR_SIGTERM_METHOD`` to ``graceful`` (the default is
-``stop``).
-
 To enable or disable running Ansible in verbose mode (with the
 ``-vvv`` argument to ansible-playbook) run ``zuul-executor verbose``
 and ``zuul-executor unverbose``.

releasenotes/notes/graceful-09c7267360190f7a.yaml

@@ -1,7 +0,0 @@
----
-features:
-  - |
-    The executor now honors the ``ZUUL_EXECUTOR_SIGTERM_METHOD``
-    environment variable to determine whether ``SIGTERM`` should be
-    equivalent to the ``stop`` command (the default) or the
-    ``graceful`` command.

zuul/cmd/executor.py

@@ -44,11 +44,7 @@ class Executor(zuul.cmd.ZuulDaemonApp):
             self.args.nodaemon = True
 
     def exit_handler(self, signum, frame):
-        graceful = os.environ.get('ZUUL_EXECUTOR_SIGTERM_METHOD', 'stop')
-        if graceful.lower() == 'graceful':
-            self.executor.graceful()
-        else:
-            self.executor.stop()
+        self.executor.stop()
 
     def start_log_streamer(self):
         pipe_read, pipe_write = os.pipe()