Previously we used a single plan action "Replace" to represent both the
destroy-before-create and the create-before-destroy variants of replacing.
However, this forces the apply graph builder to jump through a lot of
hoops to figure out which nodes need it forced on and rebuild parts of
the graph to represent that.
If we instead decide between these two cases at plan time, the actual
determination of it is more straightforward because each resource is
represented by only one node in the plan graph, and then we can ensure
we put the right nodes in the graph during DiffTransformer and thus avoid
the logic for dealing with deposed instances being spread across various
different transformers and node types.
As a nice side-effect, this also allows us to show the difference between
destroy-then-create and create-then-destroy in the rendered diff in the
CLI, although this change doesn't fully implement that yet.
We'll now show an "update" symbol prior to the argument to this synthetic
jsonencode(...) call, for consistency with how we show nested values in
other cases and to attach a verb to any "# forces replacement".
We'll also show a special form in the case where the value seems to differ
only in whitespace, so users can understand what's going on in that
hopefully-rare situation, particularly if those whitespace-only changes
end up forcing us to replace a remote object.
Since our own syntax for primitive values is similar to that of JSON, and
since we permit automatic conversions from number and bool to string, we
must do this special JSON value diff formatting only if the value is a
JSON array or object to avoid confusing results.
Because so far we've not supported dynamically-typed complex data
structures, several providers have used strings containing JSON to stand
in for these.
In order to get a readable diff in those cases, we'll recognize situations
where old and new are both JSON and present a diff of the effective value
of the JSON, using a faux call to the jsonencode(...) function to indicate
when we've done so.
This is a bit of a "cute" heuristic, but is important at least for now
until we can migrate away from that practice of passing large JSON strings
to providers and use dynamically-typed attributes instead.
This extra comment line gives us a place to show the full resource address
(since the block header line only includes type and name) and also allows
us to explain in long form the meaning of the change icon on the following
line.
This is a light adaptation of our earlier prototype of structural diff
rendering, as a starting point for what we'll actually ship. This is not
consistent with the latest mocks, so will need some additional work before
it is ready, but integrating this allows us to at least see the plan
contents while fixing up remaining issues elsewhere.
Previously we just left these out of the plan altogether, but in the new
plan types we intentionally include change information for every resource
instance, even if no changes are actually planned, to allow alternative
plan file viewers to show what isn't changing as well as what is.
This codepath is going to be significantly changed before release to make
it support structural diff of the new data types, but this lets us lean on
the old renderer to produce partial output in the mean time while we
continue to work on getting things working end-to-end after the
considerable refactoring that's been going on.
Due to how often the state and plan types are referenced throughout
Terraform, there isn't a great way to switch them out gradually. As a
consequence, this huge commit gets us from the old world to a _compilable_
new world, but still has a large number of known test failures due to
key functionality being stubbed out.
The stubs here are for anything that interacts with providers, since we
now need to do the follow-up work to similarly replace the old
terraform.ResourceProvider interface with its replacement in the new
"providers" package. That work, along with work to fix the remaining
failing tests, will follow in subsequent commits.
The aim here was to replace all references to terraform.State and its
downstream types with states.State, terraform.Plan with plans.Plan,
state.State with statemgr.State, and switch to the new implementations of
the state and plan file formats. However, due to the number of times those
types are used, this also ended up affecting numerous other parts of core
such as terraform.Hook, the backend.Backend interface, and most of the CLI
commands.
Just as with 5861dbf3fc49b19587a31816eb06f511ab861bb4 before, I apologize
in advance to the person who inevitably just found this huge commit while
spelunking through the commit history.
If we get a diagnostic message that references a source range, and if the
source code for the referenced file is available, we'll show a snippet of
the source code with the source range highlighted.
At the moment we have no cache of source code, so in practice this
codepath can never be visited. Callers to format.Diagnostic will be
gradually updated in subsequent commits.
This new method showDiagnostics takes any value that would be accepted by
tfdiags.Append and renders it to the UI.
This is intended to encourage consistent handling of the different kinds
of errors and diagnostics that can be produced, and allow richer error
objects like the HCL2 diagnostics to be easily unwrapped and shown in
their full-fidelity.
In 3ea1592 the plan rendering was refactored to add an extra indirection
of producing a display-oriented plan object first and then rendering from
that object.
There was a logic error while adapting the existing plan rendering code
to use the new display-oriented object: the core InstanceDiff object sets
the "Destroy" flag (a boolean) for both DiffDestroy and DiffDestroyCreate,
and so this code previously checked r.Destroy to recognize the
"destroy-create" case. This was incorrectly adapted to a check for the
display action being DiffDestroy, when it should actually have been
DiffDestroyCreate.
The effect of this bug was to cause the "(forces new resource)"
annotations to not be displayed on attributes, though the resource-level
information still correctly reflected that a new resource was required.
This fix restores the attribute-level annotations.
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