Add option to disable daemonization

We are double forking in the docker image and that seems to confuse
docker because the process it started has exited. Fix this by adding a
--no-daemon option to gerritbot then set that in the dockerfile. This
should run gerritbot without any additional forking.

Change-Id: I048115da5362a883360dcaf40860022ed5b63d47

Dockerfile

@@ -23,4 +23,4 @@ FROM opendevorg/python-base:3.7 as gerritbot
 COPY --from=builder /output/ /output
 RUN /output/install-from-bindep
 
-CMD ["/usr/local/bin/gerritbot", "/etc/gerritbot/gerritbot.config"]
+CMD ["/usr/local/bin/gerritbot", "--no-daemon", "/etc/gerritbot/gerritbot.config"]

gerritbot/bot.py

@@ -15,6 +15,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import argparse
 import configparser
 import daemon
 from ib3.auth import SASL
@@ -24,7 +25,6 @@ import json
 import logging.config
 import os
 import re
-import sys
 import threading
 import time
 import yaml
@@ -471,21 +471,26 @@ def _main(config):
 
 
 def main():
-    if len(sys.argv) != 2:
-        print("Usage: %s CONFIGFILE" % sys.argv[0])
-        sys.exit(1)
+    parser = argparse.ArgumentParser()
+    parser.add_argument('config_file', help='Path to the config file file')
+    parser.add_argument('--no-daemon', dest='daemon', action='store_false',
+                        help='Option to disable daemonization')
+    args = parser.parse_args()
 
     config = configparser.ConfigParser()
-    config.read(sys.argv[1])
+    config.read(args.config_file)
 
-    pid_path = ""
-    if config.has_option('ircbot', 'pid'):
-        pid_path = config.get('ircbot', 'pid')
+    if args.daemon:
+        pid_path = ""
+        if config.has_option('ircbot', 'pid'):
+            pid_path = config.get('ircbot', 'pid')
+        else:
+            pid_path = "/var/run/gerritbot/gerritbot.pid"
+
+        pid = pid_file_module.TimeoutPIDLockFile(pid_path, 10)
+        with daemon.DaemonContext(pidfile=pid):
+            _main(config)
     else:
-        pid_path = "/var/run/gerritbot/gerritbot.pid"
-
-    pid = pid_file_module.TimeoutPIDLockFile(pid_path, 10)
-    with daemon.DaemonContext(pidfile=pid):
         _main(config)