Adds the ability to target resources within modules, like:
module.mymod.aws_instance.foo
And the ability to target all resources inside a module, like:
module.mymod
Closes#1434
This reimplements my prior attempt at nipping issues where a plan did
not yield the same cycle an apply did. My prior attempt was to have
ctx.Validate generate a "Verbose" worst-case graph. It turns out that
skipping PruneDestroyTransformer to generate this graph misses important
heuristics that prevent cycles by dropping destroy nodes that are
determined to be unused.
This resulted in Validate improperly failing in scenarios where these
heuristics would have broken the cycle.
We detected the problem during the work on #1781 and worked around the
issue by reverting to the non-Verbose graph in Validate.
This commit accomplishes the original goal in a better way - by
generating the full graph and checking it once Plan has calculated the
diff. This guarantees that any graph issue that would be caught by Apply
will be caught by Plan.
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.
The `TargetTransform` was dropping provisioner nodes, which caused graph
validation to fail with messages about uninitialized provisioners when a
`terraform destroy` was attempted.
This was because `destroy` flops the dependency calculation to try and
address any nodes in the graph that "depend on" the target node. But we
still need to keep the provisioner node in the graph.
Here we switch the strategy for filtering nodes to only drop
addressable, non-targeted nodes. This should prevent us from having to
whitelist nodes to keep in the future.
closes#1541
