In #15884 we adjusted the plan output to give an explicit command to run
to apply a plan, whereas before this command was just alluded to in the
prose.
Since releasing that, we've got good feedback that it's confusing to
include such instructions when Terraform is running in a workflow
automation tool, because such tools usually abstract away exactly what
commands are run and require users to take different actions to
proceed through the workflow.
To accommodate such environments while retaining helpful messages for
normal CLI usage, here we introduce a new environment variable
TF_IN_AUTOMATION which, when set to a non-empty value, is a hint to
Terraform that it isn't being run in an interactive command shell and
it should thus tone down the "next steps" messaging.
The documentation for this setting is included as part of the "...in
automation" guide since it's not generally useful in other cases. We also
intentionally disclaim comprehensive support for this since we want to
avoid creating an extreme number of "if running in automation..."
codepaths that would increase the testing matrix and hurt maintainability.
The focus is specifically on the output of the three commands we give in
the automation guide, which at present means the following two situations:
* "terraform init" does not include the final paragraphs that suggest
running "terraform plan" and tell you in what situations you might need
to re-run "terraform init".
* "terraform plan" does not include the final paragraphs that either
warn about not specifying "-out=..." or instruct to run
"terraform apply" with the generated plan file.
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.
Previously we just assumed the reader was familiar with the idea of a
graph but didn't explain it.
Since graphs are an implementation detail of Terraform, rather than
essential information needed for new users, this revises the introduction
text to talk only about _dependencies_, which we assume the user is
familiar with as a more practical concept.
Additionally, Paul Hinze did a great talk on how Terraform uses graphs
at HashiConf 2016 which is good additional content for our existing
"Graph Internals" page, which includes a concise explanation of the
basics of graph theory.
Add an ImportStateIdFunc field to the ImportState testing functionality.
This will allow for more powerful generation of complex import state IDs
that can't be accomplished by ImportStateId or ImportStateIdPrefix
themselves.
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_.
The fact that we clean up data source state by applying a "destroy" action
for them is an implementation detail, and so should not be visible to
outside callers or to the user.
Signalling these as real destroys creates confusion for users because
they see Terraform say things like:
data.template_file.foo: Refreshing state..."
...which, to an understandably-nervous sysadmin, might make them suspect
that the underlying object was deleted, rather than just Terraform's
record of it.
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.
The implementation of ResourceAddress.Less was flawed because it was only
testing each field in the "less than" direction, and falling through in
cases where an earlier field compared greater than a later one.
Now we test for inequality first as the selector, and only fall through
if the two values for a given field are equal.
Martin Atkins