This means that terraform commands like `plan`, `apply`, `show`, and
`graph` will expand all modules by default.
While modules-as-black-boxes is still very true in the conceptual design
of modules, feedback on this behavior has consistently suggested that
users would prefer to see more verbose output by default.
The `-module-depth` flag and env var are retained to allow output to be
optionally limited / summarized by these commands.
When you specify `-verbose` you'll get the whole graph of operations,
which gives a better idea of the operations terraform performs and in
what order.
The DOT graph is now generated with a small internal library instead of
simple string building. This allows us to ensure the graph generation is
as consistent as possible, among other benefits.
We set `newrank = true` in the graph, which I've found does just as good
a job organizing things visually as manually attempting to rank the nodes
based on depth.
This also fixes `-module-depth`, which was broken post-AST refector.
Modules are now expanded into subgraphs with labels and borders. We
have yet to regain the plan graphing functionality, so I removed that
from the docs for now.
Finally, if `-draw-cycles` is added, extra colored edges will be drawn
to indicate the path of any cycles detected in the graph.
A notable implementation change included here is that
{Reverse,}DepthFirstWalk has been made deterministic. (Before it was
dependent on `map` ordering.) This turned out to be unnecessary to gain
determinism in the final DOT-level implementation, but it seemed
a desirable enough of a property that I left it in.
Most CBD-related cycles include destroy nodes, and destroy nodes were
all being pruned from the graph before staring the Validate walk.
In practice this meant that we had scenarios that would error out with
graph cycles on Apply that _seemed_ fine during Plan.
This introduces a Verbose option to the GraphBuilder that tells it to
generate a "worst-case" graph. Validate sets this to true so that cycle
errors will always trigger at this step if they're going to happen.
(This Verbose option will be exposed as a CLI flag to `terraform graph`
in a second incoming PR.)
refs #1651
