Add version property to DurableOrchestrationContext class

azure/durable_functions/models/DurableOrchestrationContext.py

@@ -100,6 +100,8 @@ def __init__(self,
         self.open_tasks = defaultdict(list)
         self.deferred_tasks: Dict[Union[int, str], Tuple[HistoryEvent, bool, str]] = {}
 
+        self._version: str = self._extract_version_from_history(self._histories)
+
     @classmethod
     def from_json(cls, json_string: str):
         """Convert the value passed into a new instance of the class.
@@ -752,3 +754,25 @@ def _get_function_name(self, name: FunctionBuilder,
                 "https://github.com/Azure/azure-functions-durable-python.\n"\
                 "Error trace: " + e.message
             raise e
+
+    @property
+    def version(self) -> Optional[str]:
+        """Get the version assigned to the orchestration instance on creation.
+
+        Returns
+        -------
+        Optional[str]
+            The version assigned to the orchestration instance on creation, or None if not found.
+        """
+        return self._version
+
+    @staticmethod
+    def _extract_version_from_history(history_events: List[HistoryEvent]) -> Optional[str]:
+        """Extract the version from the execution started event in history.
+
+        Returns None if not found.
+        """
+        for event in history_events:
+            if event.event_type == HistoryEventType.EXECUTION_STARTED:
+                return event.Version
+        return None

samples-v2/orchestration_versioning/.funcignore

@@ -0,0 +1,5 @@
+.git*
+.vscode
+local.settings.json
+test
+.venv

samples-v2/orchestration_versioning/.gitignore

@@ -0,0 +1,130 @@
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+pip-wheel-metadata/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+.python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don’t work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# Azure Functions artifacts
+bin
+obj
+appsettings.json
+local.settings.json
+.python_packages

samples-v2/orchestration_versioning/README.md

@@ -0,0 +1,44 @@
+# Versioning
+
+This directory contains a Function app that demonstrates how to make changes to an orchestrator function without breaking existing orchestration instances.
+
+The orchestrator function has two code paths:
+
+1. The old path invoking `activity_a`.
+2. The new path invoking `activity_b` instead.
+
+While `defaultVersion` in `host.json` is set to `1.0`, the orchestrator will always follow the first path, producing the following output:
+
+```
+Orchestration version: 1.0
+Suborchestration version: 1.0
+Hello from A!
+```
+
+When `defaultVersion` in `host.json` is updated (for example, to `2.0`), *new orchestration instances* will follow the new path, producing the following output:
+
+```
+Orchestration version: 2.0
+Suborchestration version: 2.0
+Hello from B!
+```
+
+What happens to *existing orchestration instances* that were started *before* the `defaultVersion` change? Waiting for an external event in the middle of the orchestrator provides a convenient opportunity to emulate a deployment while orchestration instances are still running:
+
+1. Create a new orchestration by invoking the HTTP trigger (`http_start`).
+2. Wait for the orchestration to reach the point where it is waiting for an external event.
+3. Stop the app.
+4. Change `defaultVersion` in `host.json` to `2.0`.
+5. Deploy and start the updated app.
+6. Trigger the external event.
+7. Observe that the orchestration output.
+
+```
+Orchestration version: 1.0
+Suborchestration version: 2.0
+Hello from A!
+```
+
+Note that the value returned by `context.version` is permanently associated with the orchestrator instance and is not impacted by the `defaultVersion` change. As a result, the orchestrator follows the old execution path to guarantee deterministic replay behavior.
+
+However, the suborchestration version is `2.0` because this suborchestration was created *after* the `defaultVersion` change.

samples-v2/orchestration_versioning/function_app.py

@@ -0,0 +1,46 @@
+import logging
+import azure.functions as func
+import azure.durable_functions as df
+
+myApp = df.DFApp(http_auth_level=func.AuthLevel.ANONYMOUS)
+
+@myApp.route(route="orchestrators/{functionName}")
+@myApp.durable_client_input(client_name="client")
+async def http_start(req: func.HttpRequest, client):
+    function_name = req.route_params.get('functionName')
+    instance_id = await client.start_new(function_name)
+
+    logging.info(f"Started orchestration with ID = '{instance_id}'.")
+    return client.create_check_status_response(req, instance_id)
+
+@myApp.orchestration_trigger(context_name="context")
+def my_orchestrator(context: df.DurableOrchestrationContext):
+    # context.version contains the value of defaultVersion in host.json
+    # at the moment when the orchestration was created.
+    if (context.version == "1.0"):
+        # Legacy code path
+        activity_result = yield context.call_activity('activity_a')
+    else:
+        # New code path
+        activity_result = yield context.call_activity('activity_b')
+
+    # Provide an opportunity to update and restart the app
+    context.set_custom_status("Waiting for Continue event...")
+    yield context.wait_for_external_event("Continue")
+    context.set_custom_status("Continue event received")
+
+    # New sub-orchestrations will use the current defaultVersion specified in host.json
+    sub_result = yield context.call_sub_orchestrator('my_sub_orchestrator')
+    return [f'Orchestration version: {context.version}', f'Suborchestration version: {sub_result}', activity_result]
+
+@myApp.orchestration_trigger(context_name="context")
+def my_sub_orchestrator(context: df.DurableOrchestrationContext):
+    return context.version
+
+@myApp.activity_trigger()
+def activity_a() -> str:
+    return f"Hello from A!"
+
+@myApp.activity_trigger()
+def activity_b() -> str:
+    return f"Hello from B!"

samples-v2/orchestration_versioning/host.json

@@ -0,0 +1,16 @@
+{
+  "version": "2.0",
+  "logging": {
+    "applicationInsights": {
+      "samplingSettings": {
+        "isEnabled": true,
+        "excludedTypes": "Request"
+      }
+    }
+  },
+  "extensions": {
+    "durableTask": {
+      "defaultVersion": "1.0"
+    }
+  }
+}

samples-v2/orchestration_versioning/requirements.txt

@@ -0,0 +1,7 @@
+# DO NOT include azure-functions-worker in this file
+# The Python Worker is managed by Azure Functions platform
+# Manually managing azure-functions-worker may cause unexpected issues
+
+azure-functions
+azure-functions-durable
+pytest

tests/models/test_DurableOrchestrationContext.py

@@ -100,3 +100,11 @@ def test_get_input_json_str():
     result = context.get_input()
 
     assert 'Seattle' == result['city']
+
+def test_version_equals_version_from_execution_started_event():
+    builder = ContextBuilder('test_function_context')
+    builder.history_events = []
+    builder.add_orchestrator_started_event()
+    builder.add_execution_started_event(name="TestOrchestrator", version="1.0")
+    context = DurableOrchestrationContext.from_json(builder.to_json_string())
+    assert context.version == "1.0"