Use named volumes for mounting single files

[adria-boada]

The Docker-compose documentation shows how it is possible to create a named bind mount. It should be mapped to a specific host path.

Named volumes specification works fine for directories, but they do not work for mounting single files. Podman returns an error. I am not sure if the error comes from Podman or Podman-compose.

Maybe I have poorly configured the named volume (see the example).

2c880aa9dd451f26554719bc295b9f691b1046022eb04f79c7591801a88eb593
[SERVICE] | Error: unable to start container 2c880aa9dd451f26554719bc295b9f691b1046022eb04f79c7591801a88eb593: mounting volume VOLUME-NAME for container 2c880aa9dd451f26554719bc295b9f691b1046022eb04f79c7591801a88eb593: mount: /home/USERNAME/.local/share/containers/storage/volumes/VOLUME-NAME/_data: wrong fs type, bad option, bad superblock on VOLUME-SOURCE, missing codepage or helper program, or other error.
[SERVICE] | dmesg(1) may have more information after failed mount system call.
[SERVICE] |

Example:

# Set up a tmp file.
echo "hello world" > /tmp/test-file-source

# docker-compose.yml
services:
  # This service always work, for directories and files.
  test_not_named:
    image: alpine
    volumes:
      - type: bind
        source: /tmp/test-file-source
        target: /tmp/test-file-target
    command: [ "cat", "/tmp/test-file-target" ]

  # This service returns an error for files, only works with directories.
  test_named:
    image: alpine
    volumes:
      - test_named_volume:/tmp/test-file-target
    command: [ "cat", "/tmp/test-file-target" ]
volumes:
  test_named_volume:
    driver: local
    driver_opts:
      type: bind
      device: "/tmp/test-file-target"
      o: "bind"

$ podman compose version
podman-compose version 1.6.0
podman version 5.8.2

Describe the solution you'd like

Possibility for named volumes to include named mounted files.

Describe alternatives you've considered

The first example works OK.