How to add a volume to Docker but also exclude a sub-folder

Question

I want to add some folder to the Docker container as a volume, I know that I can do this either by using ADD in the Dockerfile or by mounting it as a volume.

Now that folder is having a sub-folder, /someFolder/subFolder.

I want to mount /someFolder into the Docker container but I don't want to have it included /hostFolder/subFolder. I want to exclude this, and I also want the Docker container to be able to make changes to this sub-folder, without the consequence of having it changed on the host as well.

Can anyone help me with this?

Thanks

Answer 1

Here is what you can try if you want to have subdirectories ignored by docker-compose but persistent, 

volumes:
  node_modules:
services:
  server:
    volumes:
      - .:/app
      - node_modules:/app/node_modules

the above YAML file definition will mount your current directory as a shared volume but mount a persistent docker volume in place of your local node_modules directory.

I hope that the above explanation will resolve your query.

Answer 2

This is very similar to @Shubham's answer but a little bit different.

You can use node_modules for this purpose. Have a look at the following example:

volumes:
   - './angularApp:/opt/app'
   - /opt/app/node_modules/

Here everything in ./angularApp is mapped to /opt/app. And then I've created another volume /opt/app/node_modules/ which is an empty directory but when used locally it'll have all the files that are in /opt/app.

Comments

This did not work

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Yeah it hasn't worked for a lot of people. You can follow @Siddhart's approach. It will work

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Or else create an empty folder and map it to a target folder.

volumes:
   - ./angularApp:/opt/app
   - .empty:/opt/app/node_modules/

Answer 3

You can exclude a file by using something like this:

volumes:
   - /hostFolder:/folder
   - /dev/null:/folder/fileToBeExcluded

Answer 4

Instead of using Volume, you can use COPY. You can use it with dockerignore file to exclude the subdirectories. 

By using the .dockerignore file which is mentioned at the end of a Dockerfile, all the unwanted files can be excluded from the final image. 

This is how your dockerignore file should look:

.*
docs
mkdocs.yml
docker-compose.yml
test*
*.md

Answer 5

There is another very simple approach. What you can do is COPY the entire folder and run a cp -rm command to remove the subdirectories that are not needed. I am not sure if this affects the performance but it works for sure.

Answer 6

create an empty folder and map it to a target folder.

volumes:
   - ./angularApp:/opt/app
   - .empty:/opt/app/node_modules/