How to mount a single file in a volume

Question

I am trying to dockerize a PHP application. In the dockerfile, I download the archive, extract it, etc.

Everything works fine. However, if a new version gets released

Answer 1

TL;DR/Notice:

If you experience a directory being created in place of the file you are trying to mount, you have probably failed to supply a valid and absolute path. This is a common mistake with a silent and confusing failure mode.

File volumes are done this way in docker (absolute path example (can use env variables), and you need to mention the file name) :

    volumes:
      - /src/docker/myapp/upload:/var/www/html/upload
      - /src/docker/myapp/upload/config.php:/var/www/html/config.php

You can also do:

    volumes:
      - ${PWD}/upload:/var/www/html/upload
      - ${PWD}/upload/config.php:/var/www/html/config.php

If you fire the docker-compose from /src/docker/myapp folder