Support relative paths with bind mounts (volumes)

[borekb]

As previously discussed in moby/moby#4830, it would be useful to be able to bind-mount relative paths like this:

docker run --mount type=bind,source=host-dir,target=/app ...

Note: The original issue suggests docker run -v host-dir:/app ... which might (probably?) be confused with named volumes so I think it's more likely to expect it from the newer --mount option.

The two main motivations for this are:

• Consistency with docker-compose.
• Ability to write cross-platform docker run commands, e.g., we have a npm script that currently does something like "start": "docker run -v $PWD:/app ...". It's not easy at all to write a command that would work across Linux, macOS and Windows today.

[JonasJR]

This would be verry helpful! Been looking for this but havent found any good solution....

[matthewwo]

In my opinion, it is explicit and makes sense to resolve the path as relative path instead of absolute if the bind mount path starts with a ./.

For example:

docker run -v ./data-dump:/app/dump my-image

./ resolves as relative path in docker-compose as well which makes perfect sense and should be supported in docker cli as well imho.

[felschr]

Coming from docker-compose which supports relative paths for volumes I would've expected docker itself to support it.

[Downchuck]

Seems like this one got dropped on contributor agreement -- otherwise looks like an easy one to get through.

[matthewwo]

Would highly appreciated if there’s any updates regarding this issue.

[Downchuck]

@prankymat looks like it failed the automated tests on a rw label

[gpapin]

You can always use replace . by $(pwd) to achieve the same result in the meantime Like so : docker run -v $(pwd)/data-dump:/app/dump my-image

[borekb]

@gpapin You can't, your example won't work in some shells on Windows. See the original post where this is mentioned.

[gpapin]

You are right @borekb, this is just a workaround for linux like you mentioned in your original post.

[matthewwo]

Casual ping that I've addressed this in #1273 which just passed all the tests. Would be more than happy if any moderators could help review it! 😄