Native Python Tasks

Here is an example of a script as a local native python task: This example shows that we can still take advantage of pre-processing and variable substitution. This will allow the manual and comments section, these will also be pre-processed.

There are several ways of doing this. The following are examples.

•  There are two ways of accessing the ecflow child commands(init,event,meter, label,abort,complete). 
   We can either call the child commands directly using ecflow extension, or we can call system command to access ecflow_clent. 
   The following examples will use ecflow python extension. This requires that the PYTHONPATH is set to the directory where ecflow.so extension was installed.

• definition file:
  The default ECF_MICRO is %, this may interfere with your python scripts. In this case you either redefine it, in the task definition or directly in the python script.

    task python
      edit ECF_MICRO '$'
      edit ECF_JOB_CMD 'python $ECF_JOB$ > $ECF_JOBOUT$ 2>&1'
      label info "none"
      meter step -1 100 100
      event my_event
      

• Header: head.py

  python header

  import os, time, signal
  import ecflow
   
  print "PYTHONPATH====================================================="
  print os.environ['PYTHONPATH'].split(os.pathsep)
  
  class Client(object):
      """Encapsulate communication with the ecflow server. This will automatically call
         the child command init()/complete(), for job start/finish. It will also
         handle exceptions and signals, by calling the abort child command.
         *ONLY* one instance of this class, should be used. Otherwise zombies will be created.
      """
      def __init__(self):
        print "Creating Client"
        self.ci = ecflow.Client()
        self.ci.set_host_port("%ECF_NODE%","%ECF_PORT%")
        self.ci.set_child_pid(os.getpid())
        self.ci.set_child_path("%ECF_NAME%")
        self.ci.set_child_password("%ECF_PASS%")
        self.ci.set_child_try_no(%ECF_TRYNO%)
     
        print "Only wait 20 seconds, if the server cannot be contacted (note default is 24 hours) before failing"
        self.ci.set_child_timeout(20) 
      
        # Abort the task for the following signals
        signal.signal(signal.SIGINT,  self.signal_handler) 
        signal.signal(signal.SIGHUP,  self.signal_handler)
        signal.signal(signal.SIGQUIT, self.signal_handler)
        signal.signal(signal.SIGILL,  self.signal_handler)
        signal.signal(signal.SIGTRAP, self.signal_handler)
        signal.signal(signal.SIGIOT,  self.signal_handler)
        signal.signal(signal.SIGBUS,  self.signal_handler)
        signal.signal(signal.SIGFPE,  self.signal_handler)
        signal.signal(signal.SIGUSR1, self.signal_handler)
        signal.signal(signal.SIGUSR2, self.signal_handler)
        signal.signal(signal.SIGPIPE, self.signal_handler)
        signal.signal(signal.SIGTERM, self.signal_handler)
        signal.signal(signal.SIGXCPU, self.signal_handler)
        signal.signal(signal.SIGPWR,  self.signal_handler)
      
     def signal_handler(self,signum, frame):
        print 'Aborting: Signal handler called with signal ', signum
        self.ci.child_abort("Signal handler called with signal " + str(signum));
      
     def __enter__(self):
        self.ci.child_init()
        return self.ci
      
     def __exit__(self,ex_type,value,tb):
        print "Client:__exit__: ex_type:" + str(ex_type) + " value:" + str(value) + "\n" + str(tb)
        if ex_type != None:
           self.ci.child_abort("Aborted with exception type " + str(ex_type) + ":" + str(value))
           return False
        self.ci.child_complete()
        return False

•  task wrapper:

  $include <head.py>
  
  # This will also handle call to sys.exit(), i.e Client.__exit__ will still be called.
  with Client() as ci:
     # *******************************************************************************
     # This is where the main work is done. 
     # *******************************************************************************
     for i in range(1,100):
        ci.child_meter('step',i)
        ci.child_label('info', "value_" + str(i))
        time.sleep(1)
        
     ci.child_event('my_event')
     print "Finished event,meter and label child commands"
  
  $manual
     This is the manual section. Instead of calling python from the ECF_JOB_CMD we could alternatively place,
         #!/bin/env/python
     on the first line of this file.
  $end
  
  $comment
     Note: We do not need a include a tail.py, the head.py does it all.
  $end