Docker bind mount volumes do not propagate changes events watched by angular `ng serve` execution

Question

Following these steps:

1. Define the Dockerfile:

   FROM node:alpine
   
   RUN yarn global add @angular/cli
   RUN yarn global add node-sass
   
   RUN mkdir /volumes
   
   WORKDIR /volumes
   
   EXPOSE 4200
   
   ENTRYPOINT ["ng"]
   

2. Build an image from this Dockerfile:

   docker build -t my_angular_image .
   

3. Use the image to create a new angular app :

   // Create the new app
   docker run --rm --mount type=bind,src=$PWD,dst=/volumes my_angular_image new my-app --directory app --style scss
   // Change ownership of the generated app
   sudo chown -R $USER:$USER .
   

4. Based on the image, run a container bind mounting the app volume:

   docker run -p 4200:4200 --mount type=bind,src=$PWD/app,dst=/volumes my_angular_image serve --host 0.0.0.0
   

Results: The first compilation works as expected and the container serves the app. However, when changing the value (from host) of a file which has to be watched by ng serve in container, a new angular build is not triggered (and so, the served app is not updated).

Question: Does someone know why changing the value of a bind mount volume on host does not trigger the angular ng serve update in container (as it does when not using Docker)?

Environment:

• OS : Ubuntu 16.04
• Docker : 18.01.0-ce

Answer 1

In order to make the example working, replace step 3 by the commands below:

// Create the new app
docker run --rm --mount type=bind,src=$PWD,dst=/volumes my_angular_image new my-app --directory app --style scss
// Change ownership of the generated app
sudo chown -R $USER:$USER .
// Configure angular-cli polling:
sed -i 's/\"styleExt\": \"scss\",/"styleExt": "scss", "poll": 1000,/g' $PWD/app/.angular-cli.json

Credits:

• @PavelAgarkov's answer and its usefull links.

Answer 2

there is a hidden option for angular-cli.json named poll by specifying which you can change the way how underlining webpack watches for file updates. Links:

1. https://webpack.js.org/configuration/watch/#watchoptions-poll
2. https://github.com/angular/angular-cli/pull/1814
3. https://github.com/angular/angular-cli/wiki/angular-cli#angular-cli-config-schema