Docker: Browsersync not working correctly

I'm encountering an issue with my Node.js app using Gulp, Browsersync and Docker.

When running locally with gulp watch, everything works fine.

However, when using docker-compose up, I get an error

Cannot GET /

The Browsersync UI on port 3001 works as expected.

Running app locally:

gulp watch 

Running in Docker container:

docker-compose up 

I get error:

Cannot GET /

Error message in the web browser console:

Refused to execute inline script because it violates the following Content Security Policy directive: "default-src 'self'". Either the 'unsafe-inline' keyword, a hash ('sha256-ZfFIHrd9MzirQdadZrM3hznhYlx+PRQo8+OCWjaPDaY='), or a nonce ('nonce-...') is required to enable inline execution. Note also that 'script-src' was not explicitly set, so 'default-src' is used as a fallback

Docker compose logs: it doesn't produce any error and just logs same output as when I run it locally with gulp watch.

 docker-compose up [+] Building 0.0s (0/0) docker:desktop-linux WARN[0000] Found orphan containers ([boilerplate-app-1]) for this project. If you removed or renamed this service in your compose file, you can run this command with the --remove-orphans flag to clean it up. [+] Running 1/0 ✔ Container boilerplate-node-1 Created 0.0s Attaching to boilerplate-node-1 boilerplate-node-1 | [07:52:39] Using gulpfile /Users/filiphuhta/Documents/Projects/Bitbucket/boilerplate/gulpfile.js boilerplate-node-1 | [07:52:39] Starting 'watch'... boilerplate-node-1 | [07:52:39] Starting 'cleanDist'... boilerplate-node-1 | [07:52:39] Finished 'cleanDist' after 1.61 ms boilerplate-node-1 | [07:52:39] Starting 'buildScripts'... boilerplate-node-1 | [07:52:39] Starting 'lintScripts'... boilerplate-node-1 | [07:52:39] Starting 'buildStyles'... boilerplate-node-1 | [07:52:39] Starting 'copyFiles'... boilerplate-node-1 | Browserslist: caniuse-lite is outdated. Please run: boilerplate-node-1 | npx update-browserslist-db@latest boilerplate-node-1 | Why you should do it regularly: https://github.com/browserslist/update-db#readme boilerplate-node-1 | [07:52:40] Finished 'copyFiles' after 413 ms boilerplate-node-1 | [07:52:40] Finished 'buildScripts' after 417 ms boilerplate-node-1 | [07:52:40] Finished 'lintScripts' after 417 ms boilerplate-node-1 | [07:52:40] Finished 'buildStyles' after 419 ms boilerplate-node-1 | [07:52:40] Starting 'startServer'... boilerplate-node-1 | [07:52:40] Finished 'startServer' after 28 ms boilerplate-node-1 | [07:52:40] Starting 'watchSource'... boilerplate-node-1 | [07:52:40] Finished 'watchSource' after 1.43 ms boilerplate-node-1 | [07:52:40] Finished 'watch' after 454 ms boilerplate-node-1 | [Browsersync] Access URLs: boilerplate-node-1 | ----------------------------------- boilerplate-node-1 | Local: http://localhost:3000 boilerplate-node-1 | External: http://172.18.0.2:3000 boilerplate-node-1 | ----------------------------------- boilerplate-node-1 | UI: http://localhost:3001 boilerplate-node-1 | UI External: http://localhost:3001 boilerplate-node-1 | ----------------------------------- boilerplate-node-1 | [Browsersync] Serving files from: assets/ boilerplate-node-1 | [Browsersync] Couldn't open browser (if you are using BrowserSync in a headless environment, you might want to set the open option to false) 

gulpfile.js:

let startServer = function (done) { if (!settings.reload) return done(); // Initialize BrowserSync browserSync.init({ server: { baseDir: paths.reload, directory: true }, proxy: "node:3000", }); done(); }; 

Dockerfile:

FROM node:20 WORKDIR /usr/src/app COPY gulpfile*.js ./ COPY package*.json ./ RUN npm install --global gulp-cli RUN npm install EXPOSE 3000 3001 CMD ["gulp watch"] 

docker-compose.yml:

version: "1" services: node: build: . command: gulp watch ports: - "3000:3000" - "3001:3001" 

The browsersync UI works fine on port 3001:

I'm not that good at configuring Docker containers, so it could definitely be something that I have missed. What could cause the problem with Cannot GET / for the files that should be available on port 3000 when I use the docker container instead of locally on my machine?

Thank you for your help!