Do you know what is happening here on the host with the directory structure?

Can you answer this questions before you execute docker-compose build and docker-compose up?

1. Does the docker-compose build command creates directories on host machine?
2. Does the docker-compose up command creates directories on host machine?
3. How many folders are created on your host machine?
4. How many folders do you have in your running docker container?
5. Which directory permissions do you have on a Linux system?
6. Create a file on host ./core folder! Answer true or false if files exists on host
7. Does ./foo/core on host have a file?
8. Does ./bar/core on host have a file?
9. Now, go into the container!
10. Does /app/foo/core inside the docker container have a file?
11. docker exec -it ${CONTAINERID} ls -la /app/foo/core
12. Does /app/bar/core inside the docker container have a file?
13. docker exec -it ${CONTAINERID} ls -la /app/bar/core

Advanced

1. Delete the test file on host in the directory ./core, now!
2. Create a new file on host in the directory ./foo/core
3. Is the file on host in ./core ?
4. Is the file on host in ./bar/core ?
5. Can you find the file inside the docker container somewhere?