Implement service restart

[#1]

I've implemented dummy service like described here but it works fine for start and stop commands only.

But when I'm restarting the service it causes the following exception:

Traceback (most recent call last):
  File "/var/lib/ambari-agent/cache/stacks/HDP/2.5/services/CATALOGER/package/scripts/application.py", line 28, in <module>
    Master().execute()
  File "/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py", line 280, in execute
    method(env)
  File "/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py", line 709, in restart
    self.status(env)
  File "/var/lib/ambari-agent/cache/stacks/HDP/2.5/services/CATALOGER/package/scripts/application.py", line 25, in status
    Execute ( format("cat {pid_file}") );
  File "/usr/lib/python2.6/site-packages/resource_management/core/base.py", line 155, in __init__
    self.env.run()
  File "/usr/lib/python2.6/site-packages/resource_management/core/environment.py", line 160, in run
    self.run_action(resource, action)
  File "/usr/lib/python2.6/site-packages/resource_management/core/environment.py", line 124, in run_action
    provider_action()
  File "/usr/lib/python2.6/site-packages/resource_management/core/providers/system.py", line 273, in action_run
    tries=self.resource.tries, try_sleep=self.resource.try_sleep)
  File "/usr/lib/python2.6/site-packages/resource_management/core/shell.py", line 71, in inner
    result = function(command, **kwargs)
  File "/usr/lib/python2.6/site-packages/resource_management/core/shell.py", line 93, in checked_call
    tries=tries, try_sleep=try_sleep)
  File "/usr/lib/python2.6/site-packages/resource_management/core/shell.py", line 141, in _call_wrapper
    result = _call(command, **kwargs_copy)
  File "/usr/lib/python2.6/site-packages/resource_management/core/shell.py", line 294, in _call
    raise Fail(err_msg)
resource_management.core.exceptions.Fail: Execution of 'cat /opt/app/application.pid' returned 1. cat: /opt/app/application.pid: No such file or directory

Ok. File really does not exist (because was deleted during service stop). So I' adding lines like this:

def status(self, env):
    pid_file = "/opt/app/application.pid";
    if (os.path.exists(pid_file)):
      Execute ( format("cat {pid_file}") );

and now it checks file existence but still fails with this message:

Traceback (most recent call last):
  File "/var/lib/ambari-agent/cache/stacks/HDP/2.5/services/CATALOGER/package/scripts/application.py", line 30, in <module>
    Master().execute()
  File "/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py", line 280, in execute
    method(env)
  File "/usr/lib/python2.6/site-packages/resource_management/libraries/script/script.py", line 710, in restart
    raise Fail("Stop command finished but process keep running.")
resource_management.core.exceptions.Fail: Stop command finished but process keep running.

Can anyone suggest how to manage service restart properly?

[#2]

@Volodymyr Ostapiv can you please send over your script ?

[#3]

import sys
import time
import os.path
from resource_management import *
class Master(Script):
  def install(self, env):
    import params;
    env.set_params(params);
    print 'Install application';
    Execute('/var/lib/ambari-server/resources/stacks/HDP/2.5/services/CATALOGER/application.sh start');
  def configure(self, env):
    import params;
    env.set_params(params);
    print 'Configure application';
  def stop(self, env):
    import params;
    env.set_params(params);
    print 'Stop application';
    Execute('/var/lib/ambari-server/resources/stacks/HDP/2.5/services/CATALOGER/application.sh stop');
  def start(self, env):
    import params;
    env.set_params(params);
    print 'Start application';
    Execute('/var/lib/ambari-server/resources/stacks/HDP/2.5/services/CATALOGER/application.sh start');
  def status(self, env):
    #What should be here??
if __name__ == "__main__":
  Master().execute()