This is a significant rework of the Modules getting started guide to be
in terms of the Consul module available via the Terraform Registry. This
allows us to introduce the registry as part of the tutorial, and also
gives us some auto-generated documentation to link to as context for
the tutorial.
This new module is designed pretty differently than the one we formerly
used, and in particular it doesn't expose any server addresses for the
created Consul cluster -- due to using an auto-scaling group -- and thus
we're forced to use the (arguably-less-compelling) auto-scaling group name
for our output example.
In the 0.10 release we added an opt-in mode where Terraform would prompt
interactively for confirmation during apply. We made this opt-in to give
those who wrap Terraform in automation some time to update their scripts
to explicitly opt out of this behavior where appropriate.
Here we switch the default so that a "terraform apply" with no arguments
will -- if it computes a non-empty diff -- display the diff and wait for
the user to type "yes" in similar vein to the "terraform destroy" command.
This makes the commonly-used "terraform apply" a safe workflow for
interactive use, so "terraform plan" is now mainly for use in automation
where a separate planning step is used. The apply command remains
non-interactive when given an explicit plan file.
The previous behavior -- though not recommended -- can be obtained by
explicitly setting the -auto-approve option on the apply command line,
and indeed that is how all of the tests are updated here so that they can
continue to run non-interactively.