I had this after reading #12537 and #9047. Currently `DockerOperator`’s `volumes` argument is passed directly to docker-py’s `bind` (aka `docker -v`). But `-v`’s behaviour has long been problematic, and [Docker has been pushing users to the new `--mount` syntax instead](https://docs.docker.com/storage/bind-mounts/#choose-the--v-or---mount-flag). With #12537, it seems like `-v`’s behaviour is also confusing to some Airflow users, so I want to migrate Airflow’s internals to `--mount`.

However, `--mount` has a different syntax to `-v`, and the behaviour is also slightly different, so for compatibility reasons we can’t just do it under the hood. I can think of two possible solutions to this:

A. Deprecate `volumes` altogether and introduce `DockerOperator(mounts=...)`

This will emit a deprecation warning when the user passes `DockerOperator(volumes=...)` to tell them to convert to `DockerOperator(mounts=...)` instead. `volumes` will stay unchanged otherwise, and continue to be passed to bind mounts.

`mounts` will take a list of [`docker.types.Mount`](https://docker-py.readthedocs.io/en/stable/api.html#docker.types.Mount) to describe the mounts. They will be passed directly to the mounts API. Some shorthands could be useful as well, for example:

```python
DockerOperator(
    ...
    mounts=[
        ('/root/data1', './data1'),  # Source and target, default to volume mount.
        ('/root/data2', './data2', 'bind'),  # Bind mount.
    ],
)
```

B. Reuse `volumes` and do introspection to choose between binds and mounts

The `volumes` argument can be augmented to also accept `docker.types.Mount` instances, and internally we’ll do something like

```python
binds = []
mounts = []
for vol in volumes:
    if isinstance(vol, str):
        binds.append(vol)
    elif isintance(vol, docker.types.Mount):
        mounts.append(vol)
    else:
        raise ValueError('...')
if binds:
    warnings.warn('...', DeprecationWarning)
```

and pass the collected lists to binds and mounts respectively.

I’m very interested in hearing thoughts on this.


**Are you willing to submit a PR?**
Yes

**Related Issues**

* #12537: Confusing on the bind syntax.
* #9047: Implement mounting in `DockerSwarmOperator` (it’s a subclass of `DockerOperator`, but the `volumes` option is currently unused).

airflow/providers/docker/operators/docker_swarm.py
super().__init__(image=image, **kwargs)
        self.enable_logging = enable_logging
        self.service = None
    def execute(self, context) -> None:
        self.cli = self._get_cli()
        self.environment['AIRFLOW_TMP_DIR'] = self.tmp_dir
        return self._run_service()
    def _run_service(self) -> None:
        self.log.info('Starting docker service from image %s', self.image)
        if not self.cli:
            raise Exception("The 'cli' should be initialized before!")
        self.service = self.cli.create_service(
            types.TaskTemplate(
                container_spec=types.ContainerSpec(
                    image=self.image,
                    command=self.format_command(self.command),
                    env=self.environment,
                    user=self.user,
                    tty=self.tty,
                ),
                restart_policy=types.RestartPolicy(condition='none'),
                resources=types.Resources(mem_limit=self.mem_limit),
            ),
            name=f'airflow-{get_random_string()}',
            labels={'name': f'airflow__{self.dag_id}__{self.task_id}'},
        )
        self.log.info('Service started: %s', str(self.service))
        
        while not self.cli.tasks(filters={'service': self.service['ID']}):
            continue