K-67: Validate if train/serve file is executable

[ms-shankar]

Description

Closes issue 67

Checklist

• An issue was first created before opening this pull request
• The new code follows the kaos contribution guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests to ensure that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[jfri3d]

Shankar,

Some changes are required since the SHEBANG check forces python3... while we should only care an ENV is selected (not which).

Lastly, we should also check for the ./serve file since it is also run as an executable. Might not have been in the original issue scope but should be added.

[ImScientist]

LGTM

[aalhour]

@ms-shankar, @ImScientist, how can I test the PR changes locally?

[ms-shankar]

Hi @aalhour,

These changes can be tested by following the quickstart documentation to

1. setup workspace
2. loading mnist template
3. After loading the template, modify /templates/mnist/model-train/mnist/model/train in order to remove the shebang line at the top and change it from being an executable
4. Run the train command, and the train command should fail throwing appropriate errors.
5. Repeat the same change in the /templates/mnist/model-serve/mnist/model/serve and run the serve command to check appropriate validation errors are encountered.