Documentation for linking Stacks

[rkoron007]

Importing our docs outline into Github

Summary and pages affected:

1. Added the publish_output and upstream_input blocks to the deployment configuration reference
2. Added small mentions of inputs and outputs to "Design a Stack" article
3. New article on passing data from one stack to another

Target Release

1.11.x

CHANGELOG entry

(This is user-facing, but I'll leave the changelog entry to the team when this comes out)

• This change is user-facing and I added a changelog entry.
• This change is not user-facing.

[Uk1288]

LGTM from the technical perspective 🎉

[trujillo-adam]

Great first draft. Let me know if you have any questions about these suggestions.

[rkoron007]

Oops didn't mean this as a review - but posting anyway cause I don't want to lose my comments 😂

[rkoron007]

1. Is correct!
2. So, Stacks have a different VCS workflowIs actually a bit fuzzy depending on how you set up your Stack the first time. Most folks use a VCS-linked Stack so when you push to Github, HCP Terraform makes a new configuration version that you can apply (which is different then a deployment plan that rolls out a configuration version once it's been applied). There is also a second workflow you can go through manually, so you literally push the "Fetch configuration" button to start a configuration plan.

Since this article isn't about the second point (and we are in the Terraform language docs, not the HCP Terraform docs), I felt like it'd be distracting to talk about how to apply the configuration versus what folks care about here - which is that you have to apply it before the outputs are available.

[rkoron007]

I don't think we need to explain what an expression is here, or how to reference a value. Wouldn't that be what we'd want to put in a reference article? This is usage so that feels a bit excessive, what I'm trying to communicate is:

1. Declare a publish_output for each value you want to output from your Stack (can be value).
2. Here is an example of what that looks like.
3. To use this output, HCP Terraform needs to fetch your configuration and apply it.
4. Look at the reference article if you want to learn more about syntax.

[crw]

Approved per request of @rkoron007. Did a quick review but do not have the context to know if the content is correct. Be forewarned.