FastAPI + Github Actions CI/CD Issues

Hello,

I'm trying to deploy a FastAPI app using Github Actions. I can successfully deploy it without using the --prebuilt tag. However, I wonder if having --prebuilt is best practice? it seems to me that it prevents the whole source code to be deployed but only the new changes? I'm not quite sure but apparently Vercel can't detect .vercel/output folder even though it looks like vercel build does create it.

Command

vercel deploy --prebuilt --token=${{ secrets.VERCEL_TOKEN }}

Error

Error: ENOENT: no such file or directory, lstat '/vercel/path0/.vercel/output/builds.json'

Project Setup

vercel.json

{
  "version": 2,
  "builds": [
    {
      "src": "app/main.py",
      "use": "@vercel/python"
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "app/main.py"
    }
  ],
  "outputDirectory": ".vercel/output"
}

ci_cd_pipeline.yml

name: Run Tests and Deploy to Vercel

on:
  push:
    branches:
      - main

jobs:
  run_tests:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v2

    - name: Set up Python
      uses: actions/setup-python@v4
      with:
        python-version: '3.11.5'

    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install -r requirements.txt

    - name: Run tests
      run: |
        pytest

    # deploy to vercel
    - name: Install Vercel CLI
      run: npm install --global vercel@latest

    - name: Pull Vercel Environment Information
      run: vercel pull --yes --environment=preview --token=${{ secrets.VERCEL_TOKEN }}

    - name: Build Project Artifacts
      run: vercel build --token=${{ secrets.VERCEL_TOKEN }}

    - name: Deploy Project Artifacts to Vercel
      run: vercel deploy --prebuilt --token=${{ secrets.VERCEL_TOKEN }}

Full Log

Run vercel build --token=***
  vercel build --token=***
  shell: /usr/bin/bash -e {0}
  env:
    pythonLocation: /opt/hostedtoolcache/Python/3.11.5/x64
    PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib/pkgconfig
    Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib
  
Vercel CLI 39.1.2
WARN! Due to `builds` existing in your configuration file, the Build and Development Settings defined in your Project Settings will not apply. Learn More: https://vercel.link/unused-build-settings
Installing required dependencies...
Build Completed in .vercel/output [4s]

Run vercel deploy --prebuilt --token=***
  vercel deploy --prebuilt --token=***
  shell: /usr/bin/bash -e {0}
  env:
    pythonLocation: /opt/hostedtoolcache/Python/3.11.5/x64
    PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib/pkgconfig
    Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64
    LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib
  
Vercel CLI 39.1.2
Retrieving project…
Deploying redhorseacademy-projects/fastapi_demo
Uploading [--------------------] (0.0B/8.4MB)
(node:1865) MaxListenersExceededWarning: Possible EventTarget memory leak detected. 11 abort listeners added to [AbortSignal]. Use events.setMaxListeners() to increase limit
(Use `node --trace-warnings ...` to show where the warning was created)
Uploading [=====---------------] (2.1MB/8.4MB)
Uploading [==========----------] (4.2MB/8.4MB)
Uploading [===============-----] (6.3MB/8.4MB)
Uploading [====================] (8.4MB/8.4MB)
Inspect: https://vercel.com/redhorseacademy-projects/fastapi_demo/6e2Q9vtYnY25YHu7rtBXviBYiQUb [10s]
Preview: https://fastapidemo-juxg522yb-redhorseacademy-projects.vercel.app [10s]
Queued
Building
Error: ENOENT: no such file or directory, lstat '/vercel/path0/.vercel/output/builds.json'
https://fastapidemo-juxg522yb-redhorseacademy-projects.vercel.app
Error: Process completed with exit code 1.

Am I missing something? Since it's not an officially supported framework, do I need a custom/different configuration for FastAPI?

UPDATE 1 Well, to make matters worse, I tried building/deploying locally using Vercel CLI and it turns out I also run into the same issue despite the .vercel/output/builds.json being in the local directory.

(fastapi_env) (base) redhorseacademyPC:fastapi_demo redhorseacademy$ vercel build
Vercel CLI 39.1.2
WARN! Due to `builds` existing in your configuration file, the Build and Development Settings defined in your Project Settings will not apply. Learn More: https://vercel.link/unused-build-settings
Installing required dependencies...
✅  Build Completed in .vercel/output [9s]
(fastapi_env) (base) redhorseacademyPC:fastapi_demo redhorseacademy$ vercel deploy --prebuilt --archive=tgz
Vercel CLI 39.1.2
🔍  Inspect: https://vercel.com/redhorseacademy-projects/fastapi_demo/D7sF6esFWwpRLEbhCRdibYFNKyCn [6m]
✅  Preview: https://fastapidemo-38s604pe3-redhorseacademy-projects.vercel.app [6m]
Error: ENOENT: no such file or directory, lstat '/vercel/path0/.vercel/output/builds.json'

.vercel/output/builds.json

{
  "//": "This file was generated by the `vercel build` command. It is not part of the Build Output API.",
  "target": "preview",
  "argv": [
    "/usr/local/bin/node",
    "/usr/local/bin/vercel",
    "build"
  ],
  "builds": [
    {
      "require": "@vercel/python",
      "requirePath": "/usr/local/lib/node_modules/vercel/node_modules/@vercel/python/dist/index.js",
      "apiVersion": 3,
      "src": "app/main.py",
      "use": "@vercel/python"
    }
  ]
}

Any help is appreciated

{ "version": 2, "builds": [ { "src": "app/main.py", "use": "@vercel/python" } ], "routes": [ { "src": "/(.*)", "dest": "app/main.py" } ], "outputDirectory": ".vercel/output" }

name: Run Tests and Deploy to Vercel on: push: branches: - main jobs: run_tests: runs-on: ubuntu-latest steps: - name: Checkout code uses: actions/checkout@v2 - name: Set up Python uses: actions/setup-python@v4 with: python-version: '3.11.5' - name: Install dependencies run: | python -m pip install --upgrade pip pip install -r requirements.txt - name: Run tests run: | pytest # deploy to vercel - name: Install Vercel CLI run: npm install --global vercel@latest - name: Pull Vercel Environment Information run: vercel pull --yes --environment=preview --token=${{ secrets.VERCEL_TOKEN }} - name: Build Project Artifacts run: vercel build --token=${{ secrets.VERCEL_TOKEN }} - name: Deploy Project Artifacts to Vercel run: vercel deploy --prebuilt --token=${{ secrets.VERCEL_TOKEN }}

Run vercel build --token=*** vercel build --token=*** shell: /usr/bin/bash -e {0} env: pythonLocation: /opt/hostedtoolcache/Python/3.11.5/x64 PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib/pkgconfig Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib Vercel CLI 39.1.2 WARN! Due to `builds` existing in your configuration file, the Build and Development Settings defined in your Project Settings will not apply. Learn More: https://vercel.link/unused-build-settings Installing required dependencies... Build Completed in .vercel/output [4s] Run vercel deploy --prebuilt --token=*** vercel deploy --prebuilt --token=*** shell: /usr/bin/bash -e {0} env: pythonLocation: /opt/hostedtoolcache/Python/3.11.5/x64 PKG_CONFIG_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib/pkgconfig Python_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 Python2_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 Python3_ROOT_DIR: /opt/hostedtoolcache/Python/3.11.5/x64 LD_LIBRARY_PATH: /opt/hostedtoolcache/Python/3.11.5/x64/lib Vercel CLI 39.1.2 Retrieving project… Deploying redhorseacademy-projects/fastapi_demo Uploading [--------------------] (0.0B/8.4MB) (node:1865) MaxListenersExceededWarning: Possible EventTarget memory leak detected. 11 abort listeners added to [AbortSignal]. Use events.setMaxListeners() to increase limit (Use `node --trace-warnings ...` to show where the warning was created) Uploading [=====---------------] (2.1MB/8.4MB) Uploading [==========----------] (4.2MB/8.4MB) Uploading [===============-----] (6.3MB/8.4MB) Uploading [====================] (8.4MB/8.4MB) Inspect: https://vercel.com/redhorseacademy-projects/fastapi_demo/6e2Q9vtYnY25YHu7rtBXviBYiQUb [10s] Preview: https://fastapidemo-juxg522yb-redhorseacademy-projects.vercel.app [10s] Queued Building Error: ENOENT: no such file or directory, lstat '/vercel/path0/.vercel/output/builds.json' https://fastapidemo-juxg522yb-redhorseacademy-projects.vercel.app Error: Process completed with exit code 1.

(fastapi_env) (base) redhorseacademyPC:fastapi_demo redhorseacademy$ vercel build Vercel CLI 39.1.2 WARN! Due to `builds` existing in your configuration file, the Build and Development Settings defined in your Project Settings will not apply. Learn More: https://vercel.link/unused-build-settings Installing required dependencies... ✅ Build Completed in .vercel/output [9s] (fastapi_env) (base) redhorseacademyPC:fastapi_demo redhorseacademy$ vercel deploy --prebuilt --archive=tgz Vercel CLI 39.1.2 🔍 Inspect: https://vercel.com/redhorseacademy-projects/fastapi_demo/D7sF6esFWwpRLEbhCRdibYFNKyCn [6m] ✅ Preview: https://fastapidemo-38s604pe3-redhorseacademy-projects.vercel.app [6m] Error: ENOENT: no such file or directory, lstat '/vercel/path0/.vercel/output/builds.json'

{ "//": "This file was generated by the `vercel build` command. It is not part of the Build Output API.", "target": "preview", "argv": [ "/usr/local/bin/node", "/usr/local/bin/vercel", "build" ], "builds": [ { "require": "@vercel/python", "requirePath": "/usr/local/lib/node_modules/vercel/node_modules/@vercel/python/dist/index.js", "apiVersion": 3, "src": "app/main.py", "use": "@vercel/python" } ] }