When rendering a diff between current state and projected state, we only
show resources and outputs which have changes. However, we show a full
structural diff for these values, which includes all attributes and
blocks for a changed resource or output. The result can be a very long
diff, which makes it difficult to verify what the changed fields are.
This commit adds an experimental concise diff renderer, which suppresses
most unchanged fields, only displaying the most relevant changes and
some identifying context. This means:
- Always show all identifying attributes, initially defined as `id`,
`name`, and `tags`, even if unchanged;
- Only show changed, added, or removed primitive values: `string`,
`number`, or `bool`;
- Only show added or removed elements in unordered collections and
structural types: `map`, `set`, and `object`;
- Show added or removed elements with any surrounding unchanged elements
for sequence types: `list` and `tuple`;
- Only show added or removed nested blocks, or blocks with changed
attributes.
If any attributes, collection elements, or blocks are hidden, a count
is kept and displayed at the end of the parent scope. This ensures that
it is clear that the diff is only displaying a subset of the resource.
The experiment is currently enabled by default, but can be disabled by
setting the TF_X_CONCISE_DIFF environment variable to 0.
To avoid chasing down issues like #11635 I'm proposing we disable the
shadow graph for end users now that we have merged in all the new
graphs. I've kept it around and default-on for tests so that we can use
it to test new features as we build them. I think it'll still have value
going forward but I don't want to hold us for making it work 100% with
all of Terraform at all times.
I propose backporting this to 0-8-stable, too.
This turns the new graphs on by default and puts the old graphs behind a
flag `-Xlegacy-graph`. This effectively inverts the current 0.7.x
behavior with the new graphs.
We've incubated most of these for a few weeks now. We've found issues
and we've fixed them and we've been using these graphs internally for
awhile without any major issue. Its time to default them on and get them
part of a beta.
This creates a standard package and interface for defining, querying,
setting experiments (`-X` flags).
I expect we'll want to continue to introduce various features behind
experimental flags. I want to make doing this as easy as possible and I
want to make _removing_ experiments as easy as possible as well.
The goal with this packge has been to rely on the compiler enforcing our
experiment references as much as possible. This means that every
experiment is a global variable that must be referenced directly, so
when it is removed you'll get compiler errors where the experiment is
referenced.
This also unifies and makes it easy to grab CLI flags to enable/disable
experiments as well as env vars! This way defining an experiment is just
a couple lines of code (documented on the package).
Alisdair McDiarmid