The previous diff presentation was rather "wordy", and not very friendly
to those who can't see color either because they have color-blindness or
because they don't have a color-supporting terminal.
This new presentation uses the actual symbols used in the plan output
and tries to be more concise. It also uses some framing characters to
try to separate the different stages of "terraform plan" to make it
easier to visually navigate.
The apply command also adopts this new plan presentation, in preparation
for "terraform apply" (with interactive plan confirmation) becoming the
primary, safe workflow in the next major release.
Finally, we standardize on the terminology "perform" and "actions" rather
than "execute" and "changes" to reflect the fact that reading is now an
action and that isn't actually a _change_.
Previously the rendered plan output was constructed directly from the
core plan and then annotated with counts derived from the count hook.
At various places we applied little adjustments to deal with the fact that
the user-facing diff model is not identical to the internal diff model,
including the special handling of data source reads and destroys. Since
this logic was just muddled into the rendering code, it behaved
inconsistently with the tally of adds, updates and deletes.
This change reworks the plan formatter so that it happens in two stages:
- First, we produce a specialized Plan object that is tailored for use
in the UI. This applies all the relevant logic to transform the
physical model into the user model.
- Second, we do a straightforward visual rendering of the display-oriented
plan object.
For the moment this is slightly overkill since there's only one rendering
path, but it does give us the benefit of letting the counts be derived
from the same data as the full detailed diff, ensuring that they'll stay
consistent.
Later we may choose to have other UIs for plans, such as a
machine-readable output intended to drive a web UI. In that case, we'd
want the web UI to consume a serialization of the _display-oriented_ plan
so that it doesn't need to re-implement all of these UI special cases.
This introduces to core a new diff action type for "refresh". Currently
this is used _only_ in the UI layer, to represent data source reads.
Later it would be good to use this type for the core diff as well, to
improve consistency, but that is left for another day to keep this change
focused on the UI.
This change makes various minor adjustments to the rendering of plans
in the output of "terraform plan":
- Resources are identified using the standard resource address syntax,
rather than exposing the legacy internal representation used in the
module diff resource keys. This fixes#8713.
- Subjectively, having square brackets in the addresses made it look more
visually "off" when the same name but with different indices were
shown together with differing-length "symbols", so the symbols are now
all padded and right-aligned to three characters for consistent layout
across all operations.
- The -/+ action is now more visually distinct, using several different
colors to help communicate what it will do and including a more obvious
"(new resource required)" marker to help draw attention to this not
being just an update diff. This fixes#15350.
- The resources are now sorted in a manner that sorts index [10] after
index [9], rather than after index [1] as we did before. This makes it
easier to scan the list and avoids the common confusion where it seems
that there are only 10 items when in fact there are 11-20 items with
all the tens hiding further up in the list.
Martin Atkins