Fixes #35: Adding support for loading configs from stdin

[ghost]

Changes introduced with this PR

This PR adds support for loading config files from the stdin by specifying -f - in plugins.

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[dustinblack]

Testing locally, I no longer get a file extension error trying to pass stdin to -f -, but the same params file that works when included in the container is not working when being cat'd to the container stdin.

This works as expected w/ the smallfile-example.yaml file included in the container.

$ podman run --rm smallfile-test -f smallfile-example.yaml

But I get a typing error traceback with the stdin aproach.

$ cat smallfile-example.yaml | podman run --rm smallfile-test -f - --debug
Invalid input encountered while executing step 'workload' from file '-':
  Validation failed: Must be a dict, got NoneType

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/arcaflow_plugin_sdk/schema.py", line 1644, in _unserialize_input
    return step.input.unserialize(data)
  File "/usr/local/lib/python3.9/site-packages/arcaflow_plugin_sdk/schema.py", line 1193, in unserialize
    raise ConstraintException(path, "Must be a dict, got {}".format(type(data).__name__))
arcaflow_plugin_sdk.schema.ConstraintException: Validation failed: Must be a dict, got NoneType

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/site-packages/arcaflow_plugin_sdk/plugin.py", line 648, in _execute_file
    output_id, output_data = s(step_id, data)
  File "/usr/local/lib/python3.9/site-packages/arcaflow_plugin_sdk/schema.py", line 1708, in __call__
    input_param = self._unserialize_input(step, data)
  File "/usr/local/lib/python3.9/site-packages/arcaflow_plugin_sdk/schema.py", line 1646, in _unserialize_input
    raise InvalidInputException(e) from e
arcaflow_plugin_sdk.schema.InvalidInputException: Validation failed: Must be a dict, got NoneType

Params file for reference:

smallfile_params:
  top: "/var/tmp"
  operation: "create"
  threads: 5
  file-size: 64
  files: 100
  auto-pause: 'N'
  fsync: 'N'
  files-per-dir: 100
  dirs-per-dir: 10
  stonewall: 'Y'
  finish: 'Y'
  prefix: 'foo'
  suffix: 'bar'
  hash-into-dirs: 'N'
  same-dir: 'N'
  verify-read: 'Y'
  incompressible: 'N'
  cleanup-delay-usec-per-file: 0

[ghost]

I've updated the integration to use sys.stdin.buffer instead of sys.stdin, please check if it helps. Containers must be run with -i to use stdin.

[dustinblack]

Tested with both podman run -i and docker run -i, using both direct echo of json and cat of both yaml and json input files, and all conditions passed.