docker run add shortcut for mounting PWD

[roubles]

Description

docker run is a very powerful way to make scripts platform independent. Unfortunately the only way to pass files to a docker run is via a volume mount.

So when I have a script that works as follows:

my-awesome-script --file ./path/to/some/file

The dockerized version of calling that script becomes this monstrosity:

docker run -i -v $(pwd):/mnt containers.example.com/foo/my-awesome-script-img --file /mnt/path/to/some/file

#1273 adds support for mounting relative paths. The ask for this enhancement is to provide a shortcut (say -x) that automounts the pwd, making all files available within the docker at the same relative path location, so, the call to the dockerized version of the script could simply be:

docker run -ix containers.example.com/foo/my-awesome-script-img --file ./path/to/some/file

This will make docker run even more convenient/powerful.

This is a very frequent usecase that comes up on SO:
https://stackoverflow.com/questions/41092587/passing-file-as-argument-to-docker-container
https://stackoverflow.com/questions/44421635/how-to-get-docker-container-to-read-from-stdin

[storkinsj]

It's a shame this isn't getting more traction.
Counting on host volume mounts (dangerous, and flagged as such by cloud based systems) or "keeping docker interactive" - those are non-starters.
Curling down a file has its own set of risks and certainly inconveniences such as expiring api keys, maintaining extra servers, etc. Obviously we don't want to give a container access to a source repo.
If you are running nginx, syslog, or some other service in your docker that requires a configuration file, it is key to be able to offer this functionality to keep your container general purpose.

[thaJeztah]

Support for relative paths was added in #3469, which is part of docker 23.0; so this should now work;

touch hello.txt
docker run -v ./:/somewhere --rm alpine ls -la /somewhere
total 8
drwxr-xr-x 2 root root 4096 May 19 22:36 .
drwxr-xr-x 1 root root 4096 May 19 22:36 ..
-rw-r--r-- 1 root root 0 May 19 22:36 hello.txt