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Re: programmatically creating and airflow quirks


Yup.

On Thu, Nov 22, 2018 at 3:16 PM soma dhavala <soma.dhavala@xxxxxxxxx> wrote:

>
>
> On Nov 23, 2018, at 3:28 AM, Alex Guziel <alex.guziel@xxxxxxxxxx> wrote:
>
> It’s because of this
>
> “When searching for DAGs, Airflow will only consider files where the
> string “airflow” and “DAG” both appear in the contents of the .py file.”
>
>
> Have not noticed it.  From airflow/models.py, in process_file — (both in
> 1.9 and 1.10)
> ..
> if not all([s in content for s in (b'DAG', b'airflow')]):
> ..
> is looking for those strings and if they are not found, it is returning
> without loading the DAGs.
>
>
> So having “airflow” and “DAG”  dummy strings placed somewhere will make it
> work?
>
>
> On Thu, Nov 22, 2018 at 2:27 AM soma dhavala <soma.dhavala@xxxxxxxxx>
> wrote:
>
>>
>>
>> On Nov 22, 2018, at 3:37 PM, Alex Guziel <alex.guziel@xxxxxxxxxx> wrote:
>>
>> I think this is what is going on. The dags are picked by local variables.
>> I.E. if you do
>> dag = Dag(...)
>> dag = Dag(…)
>>
>>
>> from my_module import create_dag
>>
>> for file in yaml_files:
>> dag = create_dag(file)
>> globals()[dag.dag_id] = dag
>>
>> You notice that create_dag is in a different module. If it is in the
>> same scope (file), it will be fine.
>>
>>
>>
>> Only the second dag will be picked up.
>>
>> On Thu, Nov 22, 2018 at 2:04 AM Soma S Dhavala <soma.dhavala@xxxxxxxxx>
>> wrote:
>>
>>> Hey AirFlow Devs:
>>> In our organization, we build a Machine Learning WorkBench with AirFlow
>>> as
>>> an orchestrator of the ML Work Flows, and have wrapped AirFlow python
>>> operators to customize the behaviour. These work flows are specified in
>>> YAML.
>>>
>>> We drop a DAG loader (written python) in the default location airflow
>>> expects the DAG files.  This DAG loader reads the specified YAML files
>>> and
>>> converts them into airflow DAG objects. Essentially, we are
>>> programmatically creating the DAG objects. In order to support muliple
>>> parsers (yaml, json etc), we separated the DAG creation from loading. But
>>> when a DAG is created (in a separate module) and made available to the
>>> DAG
>>> loaders, airflow does not pick it up. As an example, consider that I
>>> created a DAG picked it, and will simply unpickle the DAG and give it to
>>> airflow.
>>>
>>> However, in current avatar of airfow, the very creation of DAG has to
>>> happen in the loader itself. As far I am concerned, airflow should not
>>> care
>>> where and how the DAG object is created, so long as it is a valid DAG
>>> object. The workaround for us is to mix parser and loader in the same
>>> file
>>> and drop it in the airflow default dags folder. During dag_bag creation,
>>> this file is loaded up with import_modules utility and shows up in the
>>> UI.
>>> While this is a solution, but it is not clean.
>>>
>>> What do DEVs think about a solution to this problem? Will saving the DAG
>>> to
>>> the db and reading it from the db work? Or some core changes need to
>>> happen
>>> in the dag_bag creation. Can dag_bag take a bunch of "created" DAGs.
>>>
>>> thanks,
>>> -soma
>>>
>>
>>
>