Due to both the nature of dynamic blocks, and the need for resources to
sometimes communicate incomplete values, we cannot validate MinItems and
MaxItems in CoerceValue.
A provider may not have the data to fill in required block values in all
cases during the resource Read operation. This is more common in import,
because there is no initial configuration or state, and it's possible
some values are only provided in the configuration.
The original intent of MinItems and MaxItems in the schema was to
enforce configuration constraints, not to enforce what the resource
could save in the state. Since the configuration is already statically
validated, and the Schema is validated against the configuration in a
separate step, we can drop these extra validation constraints in
CoerceValue and relax it to only ensure the types conform to what is
expected.
If a block was defined via "dynamic", there will be only one block value
until the expansion is known. Since we can't detect dynamic blocks at
this point, don't verify MinItems while there are unknown values in the
config.
The decoder spec can also only check for existence of a block, so limit
the check to 0 or 1.
In study of existing providers we've found a pattern we werent previously
accounting for of using a nested block type to represent a group of
arguments that relate to a particular feature that is always enabled but
where it improves configuration readability to group all of its settings
together in a nested block.
The existing NestingSingle was not a good fit for this because it is
designed under the assumption that the presence or absence of the block
has some significance in enabling or disabling the relevant feature, and
so for these always-active cases we'd generate a misleading plan where
the settings for the feature appear totally absent, rather than showing
the default values that will be selected.
NestingGroup is, therefore, a slight variation of NestingSingle where
presence vs. absence of the block is not distinguishable (it's never null)
and instead its contents are treated as unset when the block is absent.
This then in turn causes any default values associated with the nested
arguments to be honored and displayed in the plan whenever the block is
not explicitly configured.
The current SDK cannot activate this mode, but that's okay because its
"legacy type system" opt-out flag allows it to force a block to be
processed in this way anyway. We're adding this now so that we can
introduce the feature in a future SDK without causing a breaking change
to the protocol, since the set of possible block nesting modes is not
extensible.
Objects with DynamicPseudoType attributes can't be coerced within a map
if a concrete type is set. Change the Value type used to an Object when
there is a type mismatch.
The "config" package is no longer used and will be removed as part
of the 0.12 release cleanup. Since configschema is part of the
"new world" of configuration modelling, it makes more sense for
it to live as a subdirectory of the newer "configs" package.
James Bardin