Run npx webpack as part of Cloud Run deployment - docker

Question

I have a web application that's a hybrid of JS/NPM/Webpack for the frontend and Python/Django for the backend. The backend code and the source code for the frontend are stored in the code repository but the "compiled" frontend code is not as the expectation is that Webpack would build this code after deployment.
Currently, I have the following package.json:
{
"name": "Name",
"description": "...",
"scripts": {
"start": "npx webpack --config webpack.config.js"
},
"engines": {
"npm": ">=8.11.0",
"node": ">=16.15.1"
},
"devDependencies": {
[...]
},
"dependencies": {
[...]
}
}
The app is deployed to Google Cloud's Run Cloud via the deploy command, specifically:
/gcloud/google-cloud-sdk/bin/gcloud run deploy [SERVICE-NAME] --source . --region us-west1 --allow-unauthenticated
However, the command npx webpack --config webpack.config.js is apparently never executed as the built files are not generated. Django returns the error:
Error reading /app/webpack-stats.json. Are you sure webpack has generated the file and the path is correct?
What's the most elegant/efficient way to execute the build command in production? Should I include in the Dockerfile via RUN npx webpack --config webpack.config.js? I'm not even sure this would work.
Edit 1:
My current Dockerfile:
# Base image is one of Python's official distributions.
FROM python:3.8.13-slim-buster
# Declare generic app variables.
ENV APP_ENVIRONMENT=Dev
# Update and install libraries.
RUN apt update
RUN apt -y install \
sudo \
curl \
install-info \
git-all \
gnupg \
lsb-release
# Install nodejs.
RUN curl -fsSL https://deb.nodesource.com/setup_18.x | sudo -E bash -
RUN sudo apt install -y nodejs
RUN npx webpack --config webpack.config.js
# Copy local code to the container image. This is ncessary
# for the installation on Cloud Run to work.
ENV APP_HOME /app
WORKDIR $APP_HOME
COPY . ./
# Handle requirements.txt first so that we don't need to re-install our
# python dependencies every time we rebuild the Dockerfile.
COPY requirements.txt ./
RUN pip install --no-cache-dir -r requirements.txt
# Run the web service on container startup. Here we use the gunicorn
# webserver, with one worker process and 8 threads.
# For environments with multiple CPU cores, increase the number of workers
# to be equal to the cores available.
# Timeout is set to 0 to disable the timeouts of the workers to allow Cloud Run to handle instance scaling.
# Note that the $PORT variable is available by default on Cloud Run.
CMD exec gunicorn --bind :$PORT --workers 1 --threads 8 --timeout 0 --chdir project/ backbone.wsgi:application

Answer 1

According to your error message (Error reading /app/webpack-stats.json), there is a reference to /app directory in webpack.config.js. It could be the problem, because at that point the directory does not exist. Try to run npx webpack command after WORKDIR /app.