python_directive - execute a python script in current process

New in version 0.4.

Execute a piece of python code as part of task execution. You can execute any callable object imported from your external python file. The object is called in the current task process.

Parameters

parameter	required	description	type	default	choices
<kwarg>	no	arbitrarily named parameter with a value. All these key=value pairs will be passed to the python script as callable parameters.	anything
callable	yes	name of the object to call. This can be a function reference, a callable instance reference, or an instance.method reference. See examples.	str
file	yes	absolute or relative path to the python file to be executed (the task directory is considered the current working directory)	str

Return Values

The output of the python script, which must be either None or a basestring.

If this python script is supposed to be the main check of the task, it is supposed to provide output in a Task result format. This format is then used in the resultsdb directive. The easiest way to create it is to use CheckDetail objects to construct your result (or results), and then generate the YAML output with export_YAML(). Read more in Writing Tasks for Taskotron.

Exceptions

• TaskotronDirectiveError: if file can’t be read, or if callable returns something else than None or basestring
• anything that the python script raises itself

Examples

This runs a rpmlint python-wrapper to process all RPMs in the workdir:

- name: run rpmlint on downloaded rpms
  python:
      file: run_rpmlint.py
      callable: run
      workdir: ${workdir}
  export: rpmlint_output

You can pass complex python-structures as keyval parameters:

- name: run upgradepath
  python:
      file: upgradepath.py
      callable: main
      custom_args: [--debug, "${koji_tag}"]
  export: upgradepath_output

Note

If you use JSON list syntax ([a, b, c]) inside the YAML file, you must enclose any variables (and anything else containing curly braces) in quotation marks. If your variable is not supposed to be a string, you have to use YAML-native list syntax (dashes separated by line breaks). Example follows.

Depcheck uses a lot of keyval parameters, also uses both JSON list syntax and YAML list syntax, depending on its needs (${yumrepos} is not a string, but a dictionary):

- name: run depcheck
  python:
      file: run_depcheck.py
      callable: taskotron_run
      arch: ${arch}
      rpms: [ "${workdir}/downloaded_tag/" ]
      repos:
          - ${yumrepos}
          - workdir_repo: ${workdir}/downloaded_tag/
      report_format: rpms
  export: depcheck_output

There are several ways how to implement the callable object inside the python script. Given a callable name do_this_thing, possible implementations could include:

1. function reference:

   def do_this_thing(some, args):
       return "I'm a function!"
   

2. instance method reference:

   class TaskClass(object):
       def my_task(self, some, args):
           return "I'm a class method!"
   
   _task_instance = TaskClass()
   do_this_thing = _task_instance.my_task
   

3. callable instance reference:

   class EmbeddedCallClass(object):
       def __call__(self, some, args):
           return "I'm a __call__ method in a class!"
   
   do_this_thing = EmbeddedCallClass()