[python-runtime] Fix legacy invocation ASGI lifespan support by elprans · Pull Request #15268 · vercel/vercel

elprans · 2026-02-25T21:22:54Z

The non-N1 ASGI code path in vc_init.py never sent lifespan
events, so frameworks like FastAPI that depend on startup hooks
(e.g. prisma.connect() in a lifespan context manager) failed
with ClientNotConnectedError at request time.

Add a persistent event loop shared between the lifespan task and
per-request ASGICycle invocations, with an atexit handler for
clean shutdown.

Found this when testing functions with vd invoke in legacy mode.

Note

Low Risk Change

This PR adds ASGI lifespan protocol support to the Python runtime's legacy code path, implementing proper startup/shutdown event handling with a persistent event loop - a bug fix with no security, auth, or schema implications.

Adds ASGI lifespan startup/shutdown handling with asyncio.Runner for persistent event loop
Removes legacy per-request event loop creation in favor of shared runner
Adds test fixture and test case for lifespan protocol verification

^{Risk assessment for commit 2f64826.}

changeset-bot · 2026-02-25T21:23:00Z

🦋 Changeset detected

Latest commit: 2f64826

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@vercel/python-runtime	Patch

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github-actions · 2026-02-25T21:23:48Z

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github-actions · 2026-02-25T21:24:31Z

🧪 Unit Test Strategy

Comparing: 0ca7895 → 2f64826 (view diff)

Strategy: Affected packages only

✅ Only testing packages that have been modified or depend on modified packages.

Affected packages - 2 (5%)

@vercel/python
vercel

Unaffected packages - 38 (95%)

@vercel-internals/get-package-json
@vercel/backends
@vercel/build-utils
@vercel/cervel
@vercel/cli-auth
@vercel/client
@vercel/config
@vercel/detect-agent
@vercel/edge
@vercel/elysia
@vercel/error-utils
@vercel/express
@vercel/fastify
@vercel/firewall
@vercel/frameworks
@vercel/fs-detectors
@vercel/functions
@vercel/gatsby-plugin-vercel-builder
@vercel/go
@vercel/h3
@vercel/hono
@vercel/hydrogen
@vercel/koa
@vercel/nestjs
@vercel/next
@vercel/node
@vercel/oidc
@vercel/oidc-aws-credentials-provider
@vercel/python-analysis
@vercel/redwood
@vercel/related-projects
@vercel/remix-builder
@vercel/routing-utils
@vercel/ruby
@vercel/rust
@vercel/static-build
@vercel/static-config
examples

Results

Unit tests: Only affected packages will run unit tests
E2E tests: Running in parallel via E2E Tests workflow
Type checks: Only affected packages will run type checks

This comment is automatically generated based on the affected testing strategy

python/vercel-runtime/src/vercel_runtime/vc_init.py

The non-N1 ASGI code path in `vc_init.py` never sent lifespan events, so frameworks like FastAPI that depend on startup hooks (e.g. `prisma.connect()` in a lifespan context manager) failed with `ClientNotConnectedError` at request time. Add a persistent event loop shared between the lifespan task and per-request `ASGICycle` invocations, with an `atexit` handler for clean shutdown. Found this when testing functions with `vd invoke` in legacy mode.

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## @vercel/routing-utils@6.0.0 ### Major Changes - Allow `routes` to coexist with `rewrites`, `headers`, `redirects`, `cleanUrls`, and `trailingSlash`. ([#15020](#15020)) This is part of our efforts to undeprecate `routes`, which had previously been deprecated for a few years and replaced by the properties above. Now that we are undeprecating `routes` in favor of a more focused deprecation of properties within it, it is now allowed to coexist with the new properties. When used together, `routes` are inserted after `cleanUrls` and `trailingSlash` but before `redirects`, `headers`, and `rewrites` in the routing order. - Deprecate `handle`, `important`, and `override` properties in `routes` schema ([#15015](#15015)) ## @vercel/build-utils@13.6.0 ### Minor Changes - Find entrypoints for django projects. ([#15167](#15167)) ### Patch Changes - Rename fetch to nodeFetch in cases where it is an import from node-fetch ([#15234](#15234)) - [@vercel/build-utils] fix uncaught exception in streamToBuffer when stream exceeds max Buffer size ([#15276](#15276)) - Remove source and destination typo suggestions for routes schema ([#15014](#15014)) - Support function overrides in backends builder ([#15214](#15214)) - Updated dependencies \[[`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc)]: - @vercel/python-analysis@0.8.0 ## vercel@50.25.0 ### Minor Changes - Launch auto-provision flow as default for `vercel integration add` and `vercel install`. The `FF_AUTO_PROVISION_INSTALL` flag is now a kill-switch (`=0` to revert) instead of opt-in. ([#15265](#15265)) - [services] make the `experimentalServices` config the primary marker for the services flow ([#15246](#15246)) - Added command to fetch a development OIDC token ([#14785](#14785)) ### Patch Changes - Rename fetch to nodeFetch when importing from node-fetch ([#15232](#15232)) - Add setup/destroy hooks and context handling to the CLI eval runner. ([#15247](#15247)) - [services] fix dev server hang when FastAPI CLI is used ([#15274](#15274)) - Fix `--help` flag to return exit code 0 instead of 2 for the `metrics` command, aligning with standard CLI conventions. ([#15259](#15259)) - Rename fetch to nodeFetch in cases where it is an import from node-fetch ([#15234](#15234)) - Change `vercel metrics` default query output from CSV to rich text with metadata, summary tables, sparklines, and optional raw values via `--raw-values`. ([#15178](#15178)) - Removes the legacy SSO redirect flow code. ([#15228](#15228)) - Updated dependencies \[[`ad86425c3e0a1d1738cef8464dd767dd1d9a0e9a`](ad86425), [`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269), [`d9e3a570a9c6ee47afa3446ec611b6a9e4b4feec`](d9e3a57), [`2db57840669ca2fa8dadf492bd38c21bf9e3cfeb`](2db5784), [`0d42acfd22e51e51cb0e4a5aea7c19f3886ed496`](0d42acf), [`8404a7315260851495d708f1c7c6e870d7ffa007`](8404a73), [`fbf649223e6fa8b509295a85784347dcebd4a0b0`](fbf6492), [`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc), [`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585)]: - @vercel/remix-builder@5.6.0 - @vercel/python@6.17.0 - @vercel/next@4.15.35 - @vercel/node@5.6.8 - @vercel/static-build@2.8.42 - @vercel/build-utils@13.6.0 - @vercel/go@3.4.3 - @vercel/backends@0.0.38 - @vercel/elysia@0.1.41 - @vercel/express@0.1.50 - @vercel/fastify@0.1.44 - @vercel/h3@0.1.50 - @vercel/hono@0.2.44 - @vercel/koa@0.1.24 - @vercel/nestjs@0.2.45 - @vercel/redwood@2.4.9 - @vercel/rust@1.0.5 - @vercel/hydrogen@1.3.5 - @vercel/ruby@2.3.2 ## @vercel/python@6.17.0 ### Minor Changes - Find entrypoints for django projects. ([#15167](#15167)) ### Patch Changes - Rename fetch to nodeFetch when importing from node-fetch ([#15232](#15232)) - [services] fix dev server hang when FastAPI CLI is used ([#15274](#15274)) - [python] fix dev server crash on relative imports ([#15269](#15269)) - Updated dependencies \[[`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc)]: - @vercel/python-analysis@0.8.0 ## @vercel/python-analysis@0.8.0 ### Minor Changes - Find entrypoints for django projects. ([#15167](#15167)) ## @vercel/remix-builder@5.6.0 ### Minor Changes - [remix] Support future.v8_middleware option ([#15189](#15189)) ## @vercel/backends@0.0.38 ### Patch Changes - Support function overrides in backends builder ([#15214](#15214)) - Updated dependencies \[[`2db57840669ca2fa8dadf492bd38c21bf9e3cfeb`](2db5784), [`0d42acfd22e51e51cb0e4a5aea7c19f3886ed496`](0d42acf), [`8404a7315260851495d708f1c7c6e870d7ffa007`](8404a73), [`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc), [`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585)]: - @vercel/build-utils@13.6.0 ## @vercel/cervel@0.0.25 ### Patch Changes - Updated dependencies \[[`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585)]: - @vercel/backends@0.0.38 ## @vercel/client@17.2.48 ### Patch Changes - rename fetch to fetchApi ([#15231](#15231)) - Updated dependencies \[[`e64a85daec784b4fe571abe7405a80aca150007a`](e64a85d), [`2db57840669ca2fa8dadf492bd38c21bf9e3cfeb`](2db5784), [`0d42acfd22e51e51cb0e4a5aea7c19f3886ed496`](0d42acf), [`8404a7315260851495d708f1c7c6e870d7ffa007`](8404a73), [`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc), [`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585), [`af6a651229cad4ddb7fcc15bd14d06355c2b77ee`](af6a651)]: - @vercel/routing-utils@6.0.0 - @vercel/build-utils@13.6.0 ## @vercel/config@0.0.35 ### Patch Changes - Updated dependencies \[[`e64a85daec784b4fe571abe7405a80aca150007a`](e64a85d), [`af6a651229cad4ddb7fcc15bd14d06355c2b77ee`](af6a651)]: - @vercel/routing-utils@6.0.0 ## @vercel/elysia@0.1.41 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/express@0.1.50 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 - @vercel/cervel@0.0.25 ## @vercel/fastify@0.1.44 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/frameworks@3.19.1 ### Patch Changes - Rename fetch to nodeFetch when importing from node-fetch ([#15232](#15232)) ## @vercel/fs-detectors@5.8.12 ### Patch Changes - Support function overrides in backends builder ([#15214](#15214)) - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269), [`e64a85daec784b4fe571abe7405a80aca150007a`](e64a85d), [`af6a651229cad4ddb7fcc15bd14d06355c2b77ee`](af6a651)]: - @vercel/frameworks@3.19.1 - @vercel/routing-utils@6.0.0 ## @vercel/gatsby-plugin-vercel-builder@2.0.140 ### Patch Changes - Updated dependencies \[[`2db57840669ca2fa8dadf492bd38c21bf9e3cfeb`](2db5784), [`0d42acfd22e51e51cb0e4a5aea7c19f3886ed496`](0d42acf), [`8404a7315260851495d708f1c7c6e870d7ffa007`](8404a73), [`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc), [`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585)]: - @vercel/build-utils@13.6.0 ## @vercel/go@3.4.3 ### Patch Changes - Rename fetch to nodeFetch in cases where it is an import from node-fetch ([#15234](#15234)) ## @vercel/h3@0.1.50 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/hono@0.2.44 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/koa@0.1.24 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/nestjs@0.2.45 ### Patch Changes - Updated dependencies \[[`3d872692c601abeec98743d2af3a3ea19587e799`](3d87269)]: - @vercel/node@5.6.8 ## @vercel/next@4.15.35 ### Patch Changes - Rename fetch to nodeFetch when importing from node-fetch ([#15232](#15232)) ## @vercel/node@5.6.8 ### Patch Changes - Rename fetch to nodeFetch when importing from node-fetch ([#15232](#15232)) - Updated dependencies \[[`2db57840669ca2fa8dadf492bd38c21bf9e3cfeb`](2db5784), [`0d42acfd22e51e51cb0e4a5aea7c19f3886ed496`](0d42acf), [`8404a7315260851495d708f1c7c6e870d7ffa007`](8404a73), [`b3a96cc4f276ce8d16c695eabd499d3a17e73aa8`](b3a96cc), [`9a6358529f0737415110cf03d626dc9ee8e99126`](9a63585)]: - @vercel/build-utils@13.6.0 ## @vercel/static-build@2.8.42 ### Patch Changes - Rename fetch to nodeFetch in cases where it is an import from node-fetch ([#15234](#15234)) - Updated dependencies \[]: - @vercel/gatsby-plugin-vercel-builder@2.0.140 ## @vercel/python-runtime@0.5.2 ### Patch Changes - fix ASGI lifecycle events in non-IPC codepath ([#15268](#15268)) ## @vercel/python-workers@0.0.11 ### Patch Changes - Add a version bump for `@vercel/python-workers` so previously merged changes are included in the next release. ([#15254](#15254))  > [!NOTE] > Low Risk Change > > This PR is an automated Changesets release that only updates version numbers in package.json files and CHANGELOG.md files across multiple packages, with no logic or schema changes. > > - Version bumps across ~30 packages (package.json version fields) > - CHANGELOG.md updates documenting previously merged changes > - Deletion of .changeset/*.md files consumed by release automation > > <sup>Risk assessment for [commit 9b78e59](https://github.com/vercel/vercel/commit/9b78e59c7c4716d10beac3a0228e767c8565f65a).</sup>  Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

elprans requested review from a team as code owners February 25, 2026 21:22

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elprans requested review from 1st1 and fantix February 25, 2026 21:24

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elprans force-pushed the elprans/python-fix-asgi-lifespan branch from 46f8b37 to 2f64826 Compare February 25, 2026 21:37

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ricardo-agz approved these changes Feb 25, 2026

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elprans merged commit 2bab7bf into main Feb 25, 2026
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elprans deleted the elprans/python-fix-asgi-lifespan branch February 25, 2026 23:32

vercel-release-bot mentioned this pull request Feb 25, 2026

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[python-runtime] Fix legacy invocation ASGI lifespan support#15268

[python-runtime] Fix legacy invocation ASGI lifespan support#15268
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