User prompts

[lkingland]

The general architecture of the system is to provide sensible defaults for as many choice-points as possible in order to smooth the overall first-use flow. However this has the side-effect of hiding the details of what is happening, and producing sometimes inscrutable errors when the defaults are not able to be inferred. This only applies to the CLI, not the client library (which clearly deliniates the expected parameters and returns errors), so we could solve this by adding an interactive prompt when the terminal is detected to be interactive, such that defaults are clearly displayed with an option to override. This maintains the important "paved path" of default options, while exposing them for inspection and optional override.

• Prompt for choice points, such as:
  • Function name
  • Container registry
  • Skip public route (internal only)
  • Overwrite extant
• Display calculated default, allowing an [enter] to accept
• Validate user input prior to invoking the client library
• Keep the implementation separate from the client library
• Implement as a package, not hacked into cmd or main with full tests.
• Only prompt when terminal is interactive