conductor-python 1.0.19

Netflix Conductor Python SDK

Conductor Python

Software Development Kit for Netflix Conductor, written on and providing support for Python.

Quick Guide

1. Create a virtual environment

   $ virtualenv conductor
   $ source conductor/bin/activate
   $ python3 -m pip list
   Package    Version
   ---------- -------
   pip        22.0.3
   setuptools 60.6.0
   wheel      0.37.1
   

2. Install latest version of conductor-python from pypi

   $ python3 -m pip install conductor-python
   Collecting conductor-python
   Collecting certifi>=14.05.14
   Collecting urllib3>=1.15.1
   Requirement already satisfied: setuptools>=21.0.0 in ./conductor/lib/python3.8/site-packages (from conductor-python) (60.6.0)
   Collecting six>=1.10
   Installing collected packages: certifi, urllib3, six, conductor-python
   Successfully installed certifi-2021.10.8 conductor-python-1.0.7 six-1.16.0 urllib3-1.26.8
   

3. Create a worker capable of executing a Task. Example:

   from conductor.client.http.models.task import Task
   from conductor.client.http.models.task_result import TaskResult
   from conductor.client.http.models.task_result_status import TaskResultStatus
   from conductor.client.worker.worker_interface import WorkerInterface
   
   
   class SimplePythonWorker(WorkerInterface):
       def execute(self, task: Task) -> TaskResult:
           task_result = self.get_task_result_from_task(task)
           task_result.add_output_data('key', 'value')
           task_result.status = TaskResultStatus.COMPLETED
           return task_result
   

   • The add_output_data is the most relevant part, since you can store information in a dictionary, which will be sent within TaskResult as your execution response to Conductor
4. Create a main method to start polling tasks to execute with your worker. Example:

   from conductor.client.automator.task_handler import TaskHandler
   from conductor.client.example.worker.cpp.simple_cpp_worker import SimpleCppWorker
   from conductor.client.example.worker.python.simple_python_worker import SimplePythonWorker
   
   
   def main():
       workers = [
           SimpleCppWorker('cpp_task_example'),
           SimplePythonWorker('python_task_example')
       ]
       with TaskHandler(workers) as task_handler:
           task_handler.start_processes()
           task_handler.join_processes()
   
   
   if __name__ == '__main__':
       main()
   

   • This example contains two workers, each with a different execution method, capable of running the same task_definition_name
   • You can pass a Configuration object to TaskHandler, where you can set:
     • base_url: like localhost:8000/api
     • debug: true/false
     • AuthenticationSettings:

       authentication_settings=AuthenticationSettings(
           key_id='id',
           key_secret='secret'
       )
       

   • You can pass a MetricsSettings object to TaskHandler, where you can set:

     metrics_settings=MetricsSettings(
         directory='.',
         file_name='metrics.log', 
         update_interval=0.1
     )
     

5. Now that you have implemented the example, you can start the Conductor server locally:
   1. Clone Netflix Conductor repository:

      $ git clone https://github.com/Netflix/conductor.git
      $ cd conductor/
      

   2. Start the Conductor server:

      /conductor$ ./gradlew bootRun
      

   3. Start Conductor UI:

      /conductor$ cd ui/
      /conductor/ui$ yarn install
      /conductor/ui$ yarn run start
      

   You should be able to access:
   • Conductor API:
     • http://localhost:8080/swagger-ui/index.html
   • Conductor UI:
     • http://localhost:5000
6. Create a Task within Conductor:

   {
       "name": "python_task_example",
       "description": "Python task example",
       "retryCount": 3,
       "retryLogic": "FIXED",
       "retryDelaySeconds": 10,
       "timeoutSeconds": 300,
       "timeoutPolicy": "TIME_OUT_WF",
       "responseTimeoutSeconds": 180,
       "ownerEmail": "[e-mail]"
   }
   

7. Create a Workflow within Conductor:

   {
       "name": "workflow_with_python_task_example",
       "description": "Workflow with Python Task example",
       "version": 1,
       "tasks": [
         {
           "name": "python_task_example",
           "taskReferenceName": "python_task_example_ref_1",
           "inputParameters": {},
           "type": "SIMPLE"
         }
       ],
       "inputParameters": [],
       "outputParameters": {
         "workerOutput": "${python_task_example_ref_1.output}"
       },
       "schemaVersion": 2,
       "restartable": true,
       "ownerEmail": "[e-mail]",
       "timeoutPolicy": "ALERT_ONLY",
       "timeoutSeconds": 0
   }
   

8. Start a new workflow of the type you just created
9. Run your Python file with the main method

C/C++ Support

C++

1. Export your C++ functions as extern "C":
   • C++ function example (sum two integers)

     #include <iostream>
     
     extern "C" int32_t get_sum(const int32_t A, const int32_t B) {
         return A + B; 
     }
     

2. Compile and share its library:
   • C++ file name: simple_cpp_lib.cpp
   • Library output name goal: lib.so

     $ g++ -c -fPIC simple_cpp_lib.cpp -o simple_cpp_lib.o
     $ g++ -shared -Wl,-install_name,lib.so -o lib.so simple_cpp_lib.o
     

3. Create a Task definition:

   {
       "name": "cpp_task_example",
       "description": "C++ Task Example",
       "retryCount": 3,
       "timeoutSeconds": 300,
       "inputKeys": [],
       "outputKeys": [],
       "timeoutPolicy": "TIME_OUT_WF",
       "retryLogic": "FIXED",
       "retryDelaySeconds": 10,
       "responseTimeoutSeconds": 180,
       "inputTemplate": {},
       "rateLimitPerFrequency": 0,
       "rateLimitFrequencyInSeconds": 1,
       "ownerEmail": "[e-mail]",
       "backoffScaleFactor": 1
   }
   

4. Create a Workflow definition:

   {
       "name": "workflow_with_cpp_task_example",
       "description": "Workflow with C++ Task example",
       "version": 1,
       "tasks": [
           {
               "name": "cpp_task_example",
               "taskReferenceName": "cpp_task_example_ref_0",
               "inputParameters": {},
               "type": "SIMPLE",
               "decisionCases": {},
               "defaultCase": [],
               "forkTasks": [],
               "startDelay": 0,
               "joinOn": [],
               "optional": false,
               "defaultExclusiveJoinTask": [],
               "asyncComplete": false,
               "loopOver": []
           }
       ],
       "inputParameters": [],
       "outputParameters": {
           "workerOutput": "${cpp_task_example_ref_0.output}"
       },
       "schemaVersion": 2,
       "restartable": true,
       "workflowStatusListenerEnabled": false,
       "ownerEmail": "[e-mail]",
       "timeoutPolicy": "ALERT_ONLY",
       "timeoutSeconds": 0,
       "variables": {},
       "inputTemplate": {}
   }
   

5. Python Worker example:

   from conductor.client.http.models.task import Task
   from conductor.client.http.models.task_result import TaskResult
   from conductor.client.http.models.task_result_status import TaskResultStatus
   from conductor.client.worker.worker_interface import WorkerInterface
   from ctypes import cdll
   
   
   class CppWrapper:
       def __init__(self, file_path='./lib.so'):
           self.cpp_lib = cdll.LoadLibrary(file_path)
   
       def get_sum(self, X: int, Y: int) -> int:
           return self.cpp_lib.get_sum(X, Y)
   
   
   class SimpleCppWorker(WorkerInterface):
       cpp_wrapper = CppWrapper()
   
       def execute(self, task: Task) -> TaskResult:
           execution_result = self.cpp_wrapper.get_sum(1, 2)
           task_result = self.get_task_result_from_task(task)
           task_result.add_output_data(
               'sum', execution_result
           )
           task_result.status = TaskResultStatus.COMPLETED
           return task_result
   

Unit Tests

Simple validation

/conductor-python/src$ python3 -m unittest -v
test_execute_task (tst.automator.test_task_runner.TestTaskRunner) ... ok
test_execute_task_with_faulty_execution_worker (tst.automator.test_task_runner.TestTaskRunner) ... ok
test_execute_task_with_invalid_task (tst.automator.test_task_runner.TestTaskRunner) ... ok

----------------------------------------------------------------------
Ran 3 tests in 0.001s

OK

Run with code coverage

/conductor-python/src$ python3 -m coverage run --source=conductor/ -m unittest

Report:

/conductor-python/src$ python3 -m coverage report

Visual coverage results:

/conductor-python/src$ python3 -m coverage html