[Bug] SandboxWorkflowRunner doesn't use correct Pydantic field types in some cases

What are you really trying to do?

I want to be able to pass in Pydantic models with datetime fields.

To encode datetimefields, I am using the pydantic.json.pydantic_encoder but can hit this behaviour without any data conversion occurring.

Describe the bug

The SandboxWorkflowRunner restrictions are resulting in Pydantic models being created with incorrect field types.

Specifically, I am seeing models derived from Pydantic’s BaseModel class (let’s say MyDatetimeWrapper) that contain a datetime field being instantiated with a date object instead when a MyDatetimeWrapper object is created within a workflow.

Minimal Reproduction

I’ve created a code sample to illustrate the issue:

import asyncio
import dataclasses
from datetime import datetime
from uuid import uuid4

from pydantic import BaseModel
from temporalio import workflow
from temporalio.client import Client
from temporalio.worker import Worker
from temporalio.worker.workflow_sandbox import SandboxRestrictions, SandboxedWorkflowRunner

class Message(BaseModel):
    content: datetime


@workflow.defn
class Workflow:

    @workflow.run
    async def run(self, context: str) -> None:
        message = Message(content=workflow.now())
        print(f"Message in workflow with {context}: {message} (`content` type is{type(message.content)})\n")


def default_worker(client: Client, task_queue: str) -> Worker:
    return Worker(client, workflows=[Workflow], activities=[], task_queue=task_queue)


def relaxed_worker(client: Client, task_queue: str) -> Worker:
    restrictions = dataclasses.replace(
        SandboxRestrictions.default,
        invalid_module_members=dataclasses.replace(
            SandboxRestrictions.invalid_module_members_default,
            children={
                k: v for k, v in SandboxRestrictions.invalid_module_members_default.children.items() if k != "datetime"
            }
        )
    )
    runner = SandboxedWorkflowRunner(restrictions=restrictions)
    return Worker(client, workflows=[Workflow], activities=[], task_queue=task_queue, workflow_runner=runner)


async def main():
    task_queue = str(uuid4())
    client = await Client.connect("temporal:7233", namespace="default-namespace")

    async with default_worker(client, task_queue):
        context = "default sandbox"
        message = Message(content=datetime.utcnow())
        print(f"Message in main with {context}: {message} (`content` type is{type(message.content)})\n")
        handle = await client.start_workflow(Workflow.run, context, id=str(uuid4()), task_queue=task_queue)
        await handle.result()


    async with relaxed_worker(client, task_queue):
        context = "relaxed sandbox"
        message = Message(content=datetime.utcnow())
        print(f"Message in main with {context}: {message} (`content` type is{type(message.content)})\n")
        handle = await client.start_workflow(Workflow.run, context, id=str(uuid4()), task_queue=task_queue)
        await handle.result()


if __name__ == "__main__":
    asyncio.run(main())

The output from this snippet it:

Message in main with default sandbox: content=datetime.datetime(2022, 11, 18, 14, 13, 25, 326269) (`content` type is<class 'datetime.datetime'>)

Message in workflow with default sandbox: content=datetime.date(2022, 11, 18) (`content` type is<class 'datetime.date'>)

Message in main with relaxed sandbox: content=datetime.datetime(2022, 11, 18, 14, 13, 25, 360676) (`content` type is<class 'datetime.datetime'>)

Message in workflow with relaxed sandbox: content=datetime.datetime(2022, 11, 18, 14, 13, 25, 369645, tzinfo=datetime.timezone.utc) (`content` type is<class 'datetime.datetime'>)

As you can see, the default sandbox runner is resulting in content being converted to just a date despite being instantiated with a datetime.

Environment/Versions

• OS and processor: M1 Pro Mac
• Temporal Version: 1.8.4 and SDK version 0.1b3 (Pydantic 1.10.2)
• Using Docker to run Temporal server
• Python Version: Python 3.10.7

[cretz]

Here’s my small reproduction:

import asyncio
from datetime import datetime
from uuid import uuid4

from pydantic import BaseModel
from temporalio import workflow
from temporalio.exceptions import ApplicationError
from temporalio.testing import WorkflowEnvironment
from temporalio.worker import Worker


class Message(BaseModel):
    content: datetime


@workflow.defn
class Workflow:
    @workflow.run
    async def run(self) -> None:
        message = Message(content=workflow.now())
        if not isinstance(message.content, datetime):
            raise ApplicationError(f"was type {type(message.content)}")


async def main():
    async with await WorkflowEnvironment.start_local() as env:
        task_queue = str(uuid4())
        async with Worker(env.client, workflows=[Workflow], task_queue=task_queue):
            await env.client.execute_workflow(
                Workflow.run, id=str(uuid4()), task_queue=task_queue
            )


if __name__ == "__main__":
    asyncio.run(main())

Debugging now…

[cretz]

For now, I have just marked this a known issue in the README in #219. If this becomes enough of an issue, we’ll have to consider patching datetime.__subclasscheck__.