amoghrajesh opened a new pull request, #45431:
URL: https://github.com/apache/airflow/pull/45431
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closes: #45421
### Summary of changes
1. Added a minimal `Variable` user-facing definition which will be used in
DAG files by DAG authors
2. Added logic to get Variables in the context - both in "value" and "json"
format
- "value" is the raw form
- "json" is the deserialised json form, we are trying to keep the contract
between SDK and API server simple, they interact only in strings and the
responsibility of serialising + deserialising lies on the client before sending
it to the task sdk, not on the API server. This will enable multi language
support too.
#### Object Glossary
-`VariableResponse` is auto-generated and tightly coupled with the API
schema.
-`VariableResult` is runtime-specific and meant for internal communication
between Supervisor & Task Runner.
-`Variable` class here is where the public-facing, user-relevant aspects are
exposed, hiding internal details.
### Testing
DAG:
```
from __future__ import annotations
from airflow.models.baseoperator import BaseOperator
from airflow.models.dag import dag
class CustomOperator(BaseOperator):
def execute(self, context):
import os
os.environ["AIRFLOW_VAR_HI_MESSAGE"] = "hello_world"
os.environ["AIRFLOW_VAR_JSON_VAR"] = "{\r\n \"key1\":
\"value1\",\r\n \"key2\": \"value2\",\r\n \"enabled\": true,\r\n
\"threshold\": 42\r\n}"
task_id = context["task_instance"].task_id
print(f"Hello World {task_id}!")
print(context)
print(context["var"]["value"].hi_message)
print(context["var"]["json"].json_var)
@dag()
def var_from_context():
CustomOperator(task_id="hello")
var_from_context()
```
This dag tests both the scenarios of a regular `value` context as well as
`json`.
#### Case1: Variables found
Logs:
```
2c27ff9a5949
▶ Log message source details
2025-01-06 12:37:34.612546 [info ] Filling up the DagBag from
/files/dags/var_from_context.py [airflow.models.dagbag.DagBag]
2025-01-06 12:37:34.613168 [debug ] Importing
/files/dags/var_from_context.py [airflow.models.dagbag.DagBag]
2025-01-06 12:37:34.616934 [debug ] Loaded DAG <DAG: var_from_context>
[airflow.models.dagbag.DagBag]
2025-01-06 12:37:34.617131 [debug ] DAG file parsed [task]
file=/files/dags/var_from_context.py
2025-01-06 12:37:34.641905 [warning ] CustomOperator.execute cannot be
called outside TaskInstance!
[airflow.task.operators.unusual_prefix_c6632fd34e048ff55a9057c21ee5a54c16b99828_var_from_context.CustomOperator]
2025-01-06 12:37:34.642284 [info ] Hello World hello! [task]
chan=stdout
2025-01-06 12:37:34.642393 [info ] {'dag': <DAG: var_from_context>,
'inlets': [], 'map_index_template': None, 'outlets': [], 'run_id':
'manual__2025-01-06T12:37:34.037857+00:00', 'task': <Task(CustomOperator):
hello>, 'task_instance':
RuntimeTaskInstance(id=UUID('01943b9e-dadf-72eb-a47b-6c36e0fea3b7'),
task_id='hello', dag_id='var_from_context',
run_id='manual__2025-01-06T12:37:34.037857+00:00', try_number=1, map_index=-1,
task=<Task(CustomOperator): hello>), 'ti':
RuntimeTaskInstance(id=UUID('01943b9e-dadf-72eb-a47b-6c36e0fea3b7'),
task_id='hello', dag_id='var_from_context',
run_id='manual__2025-01-06T12:37:34.037857+00:00', try_number=1, map_index=-1,
task=<Task(CustomOperator): hello>), 'var': {'json': <VariableAccessor (dynamic
access)>, 'value': <VariableAccessor (dynamic access)>}, 'conn':
<ConnectionAccessor (dynamic access)>, 'dag_run':
DagRun(dag_id='var_from_context',
run_id='manual__2025-01-06T12:37:34.037857+00:00',
logical_date=datetime.datetime(2025, 1, 6, 12, 37
, 34, 37857, tzinfo=TzInfo(UTC)), data_interval_start=datetime.datetime(2025,
1, 6, 12, 37, 34, 37857, tzinfo=TzInfo(UTC)),
data_interval_end=datetime.datetime(2025, 1, 6, 12, 37, 34, 37857,
tzinfo=TzInfo(UTC)), start_date=datetime.datetime(2025, 1, 6, 12, 37, 34,
492777, tzinfo=TzInfo(UTC)), end_date=None, run_type=<DagRunType.MANUAL:
'manual'>, conf={}), 'data_interval_end': datetime.datetime(2025, 1, 6, 12, 37,
34, 37857, tzinfo=TzInfo(UTC)), 'data_interval_start': datetime.datetime(2025,
1, 6, 12, 37, 34, 37857, tzinfo=TzInfo(UTC)), 'logical_date':
datetime.datetime(2025, 1, 6, 12, 37, 34, 37857, tzinfo=TzInfo(UTC)), 'ds':
'2025-01-06', 'ds_nodash': '20250106', 'task_instance_key_str':
'var_from_context__hello__20250106', 'ts': '2025-01-06T12:37:34.037857+00:00',
'ts_nodash': '20250106T123734', 'ts_nodash_with_tz':
'20250106T123734.037857+0000'} [task] chan=stdout
2025-01-06 12:37:34.642268 [debug ] Sending request [task]
json={"key":"hi_message","type":"GetVariable"}
2025-01-06 12:37:34.648998 [info ] Variable(key='hi_message',
value='hello_world', description=None) [task] chan=stdout
2025-01-06 12:37:34.649000 [debug ] Sending request [task]
json={"key":"json_var","type":"GetVariable"}
2025-01-06 12:37:34.652506 [warning ] Pydantic serializer warnings:
Expected `str` but got `dict` with value `{'api_key': '12345', 'region':
'us-east-1'}` - serialized value may not be as expected [py.warnings]
category=UserWarning
filename=/usr/local/lib/python3.9/site-packages/pydantic/main.py lineno=426
2025-01-06 12:37:34.652586 [debug ] Sending request [task]
json={"state":"success","end_date":"2025-01-06T12:37:34.652550Z","type":"TaskState"}
2025-01-06 12:37:34.652845 [info ] Variable(key='json_var',
value={'api_key': '12345', 'region': 'us-east-1'}, description=None) [task]
chan=stdout
```
#### Case 2: Variable not found
Logs:
```
2c27ff9a5949
▶ Log message source details
2025-01-06 12:34:57.712062 [info ] Filling up the DagBag from
/files/dags/var_from_context.py [airflow.models.dagbag.DagBag]
2025-01-06 12:34:57.712579 [debug ] Importing
/files/dags/var_from_context.py [airflow.models.dagbag.DagBag]
2025-01-06 12:34:57.717120 [debug ] Loaded DAG <DAG: var_from_context>
[airflow.models.dagbag.DagBag]
2025-01-06 12:34:57.717434 [debug ] DAG file parsed [task]
file=/files/dags/var_from_context.py
2025-01-06 12:34:57.743903 [warning ] CustomOperator.execute cannot be
called outside TaskInstance!
[airflow.task.operators.unusual_prefix_c6632fd34e048ff55a9057c21ee5a54c16b99828_var_from_context.CustomOperator]
2025-01-06 12:34:57.744163 [info ] Hello World hello! [task]
chan=stdout
2025-01-06 12:34:57.744270 [info ] {'dag': <DAG: var_from_context>,
'inlets': [], 'map_index_template': None, 'outlets': [], 'run_id':
'manual__2025-01-06T12:34:56.856856+00:00', 'task': <Task(CustomOperator):
hello>, 'task_instance':
RuntimeTaskInstance(id=UUID('01943b9c-74e4-7b93-ba7e-7401dde98944'),
task_id='hello', dag_id='var_from_context',
run_id='manual__2025-01-06T12:34:56.856856+00:00', try_number=1, map_index=-1,
task=<Task(CustomOperator): hello>), 'ti':
RuntimeTaskInstance(id=UUID('01943b9c-74e4-7b93-ba7e-7401dde98944'),
task_id='hello', dag_id='var_from_context',
run_id='manual__2025-01-06T12:34:56.856856+00:00', try_number=1, map_index=-1,
task=<Task(CustomOperator): hello>), 'var': {'json': <VariableAccessor (dynamic
access)>, 'value': <VariableAccessor (dynamic access)>}, 'conn':
<ConnectionAccessor (dynamic access)>, 'dag_run':
DagRun(dag_id='var_from_context',
run_id='manual__2025-01-06T12:34:56.856856+00:00',
logical_date=datetime.datetime(2025, 1, 6, 12, 34
, 56, 856856, tzinfo=TzInfo(UTC)), data_interval_start=datetime.datetime(2025,
1, 6, 12, 34, 56, 856856, tzinfo=TzInfo(UTC)),
data_interval_end=datetime.datetime(2025, 1, 6, 12, 34, 56, 856856,
tzinfo=TzInfo(UTC)), start_date=datetime.datetime(2025, 1, 6, 12, 34, 57,
589490, tzinfo=TzInfo(UTC)), end_date=None, run_type=<DagRunType.MANUAL:
'manual'>, conf={}), 'data_interval_end': datetime.datetime(2025, 1, 6, 12, 34,
56, 856856, tzinfo=TzInfo(UTC)), 'data_interval_start': datetime.datetime(2025,
1, 6, 12, 34, 56, 856856, tzinfo=TzInfo(UTC)), 'logical_date':
datetime.datetime(2025, 1, 6, 12, 34, 56, 856856, tzinfo=TzInfo(UTC)), 'ds':
'2025-01-06', 'ds_nodash': '20250106', 'task_instance_key_str':
'var_from_context__hello__20250106', 'ts': '2025-01-06T12:34:56.856856+00:00',
'ts_nodash': '20250106T123456', 'ts_nodash_with_tz':
'20250106T123456.856856+0000'} [task] chan=stdout
2025-01-06 12:34:57.744177 [debug ] Sending request [task]
json={"key":"hi_message","type":"GetVariable"}
2025-01-06 12:34:57.749149 [debug ] Sending request [task]
json={"state":"failed","end_date":"2025-01-06T12:34:57.749108Z","type":"TaskState"}
```
TODO:
- [ ] Writing variables from task SDK
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