Support `terraform apply`?

[glenjamin]

As terraform apply now produces a diff and then prompts for a yes to apply, it would be neat if landscape could handle this too.

I hope this would mostly be a case of streaming the output through rather than buffering - but it might be more involved.

[sds]

Hey @glenjamin, would love to merge a pull request adding support for streaming!

[glenjamin]

I had a bit of a look into this. It seems doable but a bit more invasive than i'd initially hoped.

A high level outline of what is required to do this properly:

• [ ] modify grammar to remove plan and resource_list
• [ ] Flip Printer.process_stream and process_string around, so print delegates to stream
• [ ] Have stream read in lines at a time and apply the exclusion regexes
• [ ] Feed those lines into the parser one at a time
• [ ] Modify the TerraformPlan code to work on chunks - see this treetop thread
• [ ] Modify the printer to spit out chunk at a time too?

This would be cool as you'd also get incremental feedback - and could even maybe pass-through some of the underlying terraform incremental feedback messages?

While writing this up I realised this is overthinking it somewhat, and there's a cheat's way to do this:

• [ ] Tweak Printer.process_stream so that it also treats the apply prompt as the end of the input
• [ ] After outputting the formatted plan, output our own prompt

I'm going to have a go at the latter at some point, and I might have a go at the former if i'm feeling adventurous.

[sds]

Implemented in #54.

[glenjamin]

Do you think it's worth leaving an issue open for full streaming support in case someone else runs into it and wants to give it a go?