Add Modal Serverless Worker integration by harish-narayanappa-10 · Pull Request #1970 · temporalio/sdk-python

harish-narayanappa-10 · 2026-10-15T08:04:42Z

Summary

Add temporalio.contrib.modal.worker for running a versioned Temporal Worker during one Modal Function invocation
Create a fresh client and worker per invocation with Modal-tuned concurrency, polling, identity, Worker Versioning, and eager-activity defaults
Derive the worker lifecycle budget from the declared Modal Function timeout and shut down the worker and hooks before the deadline
Document a complete Activity, Workflow, and Modal Function setup

Testing

uv run pytest tests/contrib/modal/worker/test_modal_worker.py
Pyright, mypy, and basedpyright on temporalio/contrib/modal and tests/contrib/modal
poe format
poe gen-docs

…dal-sdk-python

CLAassistant · 2026-10-15T08:05:10Z

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CLAassistant · 2026-10-15T08:05:16Z

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seanbollin · 2026-10-15T16:40:06Z

+"""Run Temporal workers inside Modal Functions.
+
+The integration owns the worker lifecycle within one already-running Modal
+Function invocation. Authentication and invocation between a controller and


Can remove "Authentication and invocation ..."

We don't need to call out things we didn't do

The LLMs are pretty bad at these types of comments - can you go through the comments in the PR in general and make sure it isn't adding any text that a user wouldn't expect to see or that is unrelated to the plugins purpose

addressed/reviewed as suggested

seanbollin · 2026-10-15T16:55:16Z

+    config.execution_timeout = WORKER_EXECUTION_TIMEOUT
+
+
+@app.function(timeout=int(MODAL_FUNCTION_TIMEOUT.total_seconds()))


Can you add a simple workflow and activity to all the example code?

seanbollin · 2026-10-15T17:02:42Z

+
+    Call this from a top-level async function decorated with
+    ``@app.function``. A fresh Temporal client and worker are created for every
+    invocation. The worker polls until its execution budget approaches the


Can you talk about this behavior in the main README example? As a customer I think I'd want to know very clearly what this is doing - stops polling at time T, then allows X time for finishing activities etc.

added lifecycle timeline to the README showing setup, when polling stops, Modal deadline etc

seanbollin · 2026-10-15T17:30:03Z

+
+WORKER_EXECUTION_TIMEOUT = timedelta(minutes=2)
+MODAL_FUNCTION_TIMEOUT = (
+    WORKER_EXECUTION_TIMEOUT + MIN_FUNCTION_TIMEOUT_HEADROOM


Why expose this to the customer? If I'm a customer I just want to simply state that my functions run for a maximum of 5 minutes. But with this approach they need to do math to figure out how long their functions run.

Can't we just set the @app.function timeout to 5 minutes, set the modal_function_timeout to 5 minutes, and then let the internal run_worker code subtract the MIN_FUNCTION_TIMEOUT_HEADROOM

Updated as suggested. @app.function(timeout=...) and modal_function_timeout now use the same value

seanbollin · 2026-10-15T17:41:41Z

+    base_connect_config: ClientConnectConfig = {**profile.to_client_connect_config()}
+
+    base_worker_config: WorkerConfig = {}
+    apply_modal_worker_defaults(base_worker_config)


This sets graceful_shutdown_timeout to 5s (DEFAULT_GRACEFUL_SHUTDOWN_TIMEOUT) and then when you compute graceful_timeout on line 240 it always uses this 5s value not the user supplied configuration value. So shutdown_deadline_buffer is always 7s

Polling stops with 7 seconds of budget left no matter what they set for graceful_shutdown_timeout

Fixed. The default shutdown buffer is now calculated after configure from the final graceful_shutdown_timeout, plus two seconds for shutdown hooks

seanbollin · 2026-10-15T17:46:20Z

+    config.worker_config["activities"] = [my_activity]
+    config.execution_timeout = WORKER_EXECUTION_TIMEOUT
+
+


If you set this:

@app.function(timeout=900) # 15-minute container
async def temporal_worker():
await run_worker(VERSION, configure,
modal_function_timeout=timedelta(minutes=15))

execution_timeout is still 5 minutes if you don't set it in the config

Fixed. execution_timeout now defaults to modal_function_timeout minus the internal 15-second headroom

tconley1428

Discussing offline a final location for this code.

…thon into modal-sdk-python

harish-narayanappa-10 added 3 commits October 14, 2026 14:33

initial changes to support modal

0c58835

python sdk changes to support modal provider

d51fe57

Merge branch 'main' of ssh://github.com/temporalio/sdk-python into mo…

ae12140

…dal-sdk-python

harish-narayanappa-10 marked this pull request as ready for review October 15, 2026 16:08

harish-narayanappa-10 requested a review from a team as a code owner October 15, 2026 16:08

seanbollin reviewed Oct 15, 2026

View reviewed changes

tconley1428 requested changes Oct 16, 2026

View reviewed changes

harish-narayanappa-10 added 3 commits October 16, 2026 11:30

Merge branch 'main' into modal-sdk-python

371a18f

addressing review comments

64653bb

Merge branch 'modal-sdk-python' of ssh://github.com/temporalio/sdk-py…

48b839d

…thon into modal-sdk-python

		config.execution_timeout = WORKER_EXECUTION_TIMEOUT


		@app.function(timeout=int(MODAL_FUNCTION_TIMEOUT.total_seconds()))

		config.worker_config["activities"] = [my_activity]
		config.execution_timeout = WORKER_EXECUTION_TIMEOUT

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harish-narayanappa-10 Oct 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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harish-narayanappa-10 commented Oct 15, 2026 •

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CLAassistant commented Oct 15, 2026 •

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harish-narayanappa-10 Oct 19, 2026 •

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