Previously the behavior for -target when given a module address was to
target only resources directly within that module, ignoring any resources
defined in child modules.
This behavior turned out to be counter-intuitive, since users expected
the -target address to be interpreted hierarchically.
We'll now use the new "Contains" function for addresses, which provides
a hierarchical "containment" concept that is more consistent with user
expectations. In particular, it allows module.foo to match
module.foo.module.bar.aws_instance.baz, where before that would not have
been true.
Since Contains isn't commutative (unlike Equals) this requires some
special handling for targeting specific indices. When given an argument
like -target=aws_instance.foo[0], the initial graph construction (for
both plan and refresh) is for the resource nodes from configuration, which
have not yet been expanded to separate indexed instances. Thus we need
to do the first pass of TargetsTransformer in mode where indices are
ignored, with the work then completed by the DynamicExpand method which
re-applies the TargetsTransformer in index-sensitive mode.
This is a breaking change for anyone depending on the previous behavior
of -target, since it will now select more resources than before. There is
no way provided to obtain the previous behavior. Eventually we may support
negative targeting, which could then combine with positive targets to
regain the previous behavior as an explicit choice.
Martin Atkins