- type: WriteFile
  fileMode: 755

The above example does not make the file executable and I have found it in a couple of platform configs. Since it does not work, I have seen the WriteFile command followed by "chmod" executions.

I believe the correct way to write the mode is "0o755" but it's not mentioned in the documentation, and I haven't tested yet to see if it works. (EDIT: it does not work, it is not possible to set the FileMode to 0o755, the coin scheduler returns the error:

Adjusting configurations returned error message: 'invalid literal for int() with base 10: '0o755'' 

In pre-existing platform configs I also find modes of "493" and "420" which apparently are in decimal, but they really don't mean anything to people reading them, if they don't know the context.