[python] add support for generic ASGI/WSGI applications to `vc dev` by nsidnev · Pull Request #15174 · vercel/vercel

nsidnev · 2026-02-20T03:45:55Z

Unifies vc_init_dev_asgi.py and vc_init_dev_wsgi.py into a single vc_init_dev.py script, which handles both interfaces. This also allows arbitrary Python ASGI/WSGI frameworks (such as Sanic or Blacksheep) to be run through the dev server, rather than just FastAPI or Flask, as is right now. This works for both, the current single app per project mode and for multi-service mode.

BaseHTTPRequestHandler-based functions are still served directly, as before.

Warning

High Risk Change

This PR refactors Python dev server code to unify ASGI/WSGI handling and expands framework support from only FastAPI/Flask to any Python framework, which is a significant behavioral change in the dev server infrastructure.

Expands framework support from FastAPI/Flask-only to generic Python ASGI/WSGI apps
Unifies two separate shim files (vc_init_dev_asgi.py, vc_init_dev_wsgi.py) into single vc_init_dev.py
Changes port detection from regex-based stdout parsing to port reachability polling

^{Risk assessment for commit 0bf1c7e.}

changeset-bot · 2026-02-20T03:46:01Z

🦋 Changeset detected

Latest commit: 0bf1c7e

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

This PR includes changesets to release 2 packages

Name	Type
@vercel/python	Minor
vercel	Patch

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github-actions · 2026-02-20T03:46:06Z

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github-actions · 2026-02-20T03:49:48Z

🧪 Unit Test Strategy

Comparing: d269bdc → 0bf1c7e (view diff)

Strategy: Code changed outside of a package - running all unit tests

⚠️ All unit tests will run because global code changes could impact all packages.

Affected packages - 40 (100%)

@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
@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
vercel

Results

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

This comment is automatically generated based on the affected testing strategy

packages/python/vc_init_dev.py

…ric-python-apps-not-only

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/build-utils@13.5.0 ### Minor Changes - Add django experimental framework. ([#15196](#15196)) ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/python-analysis@0.7.0 ## @vercel/frameworks@3.19.0 ### Minor Changes - Add django experimental framework. ([#15196](#15196)) ## @vercel/python@6.16.0 ### Minor Changes - [python] add support for running generic ASGI/WSGI applications to vc dev ([#15174](#15174)) ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/python-analysis@0.7.0 ## @vercel/python-analysis@0.7.0 ### Minor Changes - Add django experimental framework. ([#15196](#15196)) ## @vercel/backends@0.0.37 ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/build-utils@13.5.0 ## @vercel/cervel@0.0.24 ### Patch Changes - Updated dependencies \[]: - @vercel/backends@0.0.37 ## vercel@50.22.2 ### Patch Changes - fix(cli): add `integration-resource` command to `vc --help` output ([#15191](#15191)) - fix(cli): filter empty strings from trailing commas in array metadata ([#15163](#15163)) - fix(cli): add non-TTY guards and fix exit codes in marketplace commands ([#15158](#15158)) - Adding in a non-interactive flag for env command ([#14912](#14912)) - fix(cli): unify teamId scoping for all marketplace integration commands ([#15183](#15183)) - Updated dependencies \[[`3c4aff4acbfa603705556d145236b8a9ef106331`](3c4aff4), [`984d44875f959058f5d13fea27373785b1d66b6f`](984d448), [`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/next@4.15.32 - @vercel/python@6.16.0 - @vercel/build-utils@13.5.0 - @vercel/backends@0.0.37 - @vercel/elysia@0.1.40 - @vercel/express@0.1.49 - @vercel/fastify@0.1.43 - @vercel/go@3.4.1 - @vercel/h3@0.1.49 - @vercel/hono@0.2.43 - @vercel/hydrogen@1.3.5 - @vercel/koa@0.1.23 - @vercel/nestjs@0.2.44 - @vercel/node@5.6.7 - @vercel/redwood@2.4.9 - @vercel/remix-builder@5.5.10 - @vercel/ruby@2.3.1 - @vercel/rust@1.0.5 - @vercel/static-build@2.8.41 ## @vercel/client@17.2.46 ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/build-utils@13.5.0 ## @vercel/elysia@0.1.40 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/express@0.1.49 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 - @vercel/cervel@0.0.24 ## @vercel/fastify@0.1.43 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/fs-detectors@5.8.10 ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/frameworks@3.19.0 ## @vercel/gatsby-plugin-vercel-builder@2.0.139 ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/build-utils@13.5.0 ## @vercel/h3@0.1.49 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/hono@0.2.43 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/koa@0.1.23 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/nestjs@0.2.44 ### Patch Changes - Updated dependencies \[]: - @vercel/node@5.6.7 ## @vercel/next@4.15.32 ### Patch Changes - Revert per function builder support ([#15209](#15209)) ## @vercel/node@5.6.7 ### Patch Changes - Updated dependencies \[[`cb79f6f8080fddd3673a8911566085e0265b060b`](cb79f6f)]: - @vercel/build-utils@13.5.0 ## @vercel/static-build@2.8.41 ### Patch Changes - Updated dependencies \[]: - @vercel/gatsby-plugin-vercel-builder@2.0.139 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

[python] add support for generic ASGI/WSGI applications to vc dev

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nsidnev added 2 commits February 20, 2026 10:49

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Merge branch 'main' into nsidnev/py-55-vercel-dev-should-support-gene…

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…ric-python-apps-not-only

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nsidnev marked this pull request as ready for review February 20, 2026 16:03

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Merge branch 'main' into nsidnev/py-55-vercel-dev-should-support-gene…

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nsidnev merged commit 984d448 into main Feb 20, 2026
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nsidnev deleted the nsidnev/py-55-vercel-dev-should-support-generic-python-apps-not-only branch February 20, 2026 21:35

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[python] add support for generic ASGI/WSGI applications to `vc dev`#15174

[python] add support for generic ASGI/WSGI applications to `vc dev`#15174
nsidnev merged 5 commits intomainfrom
nsidnev/py-55-vercel-dev-should-support-generic-python-apps-not-only

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