@ -108,28 +108,15 @@ func (n *nodeExpandPlannableResource) DynamicExpand(ctx EvalContext) (*Graph, tf
expander := ctx . InstanceExpander ( )
moduleInstances := expander . ExpandModule ( n . Addr . Module )
// The possibility of partial-expanded modules and resources is
// currently guarded by a language experiment, and so to minimize the
// risk of that experiment impacting mainline behavior we currently
// branch off into an entirely-separate codepath in those situations,
// at the expense of duplicating some of the logic for behavior this
// method would normally handle.
//
// Normally language experiments are confined to only a single module,
// but this one has potential cross-module impact once enabled for at
// least one, and so this flag is true if _any_ module in the configuration
// has opted in to the experiment. Our intent is for this different
// codepath to produce the same results when there aren't any
// partial-expanded modules, but bugs might make that not true and so
// this is conservative to minimize the risk of breaking things for
// those who aren't participating in the experiment.
//
// TODO: If this experiment is stablized then we should aim to combine
// these two codepaths back together, so that the behavior is less likely
// to diverge under future maintenence.
if n . unknownInstancesExperimentEnabled {
// The possibility of partial-expanded modules and resources is guarded by a
// top-level option for the whole plan, so that we can preserve mainline
// behavior for the modules runtime. So, we currently branch off into an
// entirely-separate codepath in those situations, at the expense of
// duplicating some of the logic for behavior this method would normally
// handle.
if ctx . Deferrals ( ) . DeferralAllowed ( ) {
pem := expander . UnknownModuleInstances ( n . Addr . Module )
return n . dynamicExpandWith UnknownInstancesExperiment ( ctx , moduleInstances , pem )
return n . dynamicExpandWithDeferralAllowed ( ctx , moduleInstances , pem )
}
// Lock the state while we inspect it
@ -218,22 +205,14 @@ func (n *nodeExpandPlannableResource) DynamicExpand(ctx EvalContext) (*Graph, tf
return & g , diags
}
// dynamicExpandWithUnknownInstancesExperiment is a temporary experimental
// variant of DynamicExpand that we use when at least one module is
// participating in the "unknown_instances" language experiment.
//
// This is not exactly in the typical spirit of language experiments in that
// the effect is not scoped only to the module where the opt-in is declared:
// if there are bugs in this method then they could potentially also affect
// resources in modules not directly participating. We're accepting that
// as a pragmatic compromise here since unknown expansion of a module call
// is inherently a cross-module concern.
// dynamicExpandWithDeferralAllowed is a variant of DynamicExpand that we use
// when deferred actions are enabled for the current plan.
//
// If we move forward with unknown instances as a stable feature then we
// should find a way to meld this logic with the main DynamicExpand logic,
// but it's separate for now to minimize the risk of the experiment impacting
// configurations that are not opted into it.
func ( n * nodeExpandPlannableResource ) dynamicExpandWith UnknownInstancesExperiment ( globalCtx EvalContext , knownInsts [ ] addrs . ModuleInstance , partialInsts addrs . Set [ addrs . PartialExpandedModule ] ) ( * Graph , tfdiags . Diagnostics ) {
// Once deferred actions are more stable and robust in the stacks runtime, it
// would be nice to integrate this logic a little better with the main
// DynamicExpand logic, but it's separate for now to minimize the risk of
// stacks-specific behavior impacting configurations that are not opted into it.
func ( n * nodeExpandPlannableResource ) dynamicExpandWithDeferralAllowed ( globalCtx EvalContext , knownInsts [ ] addrs . ModuleInstance , partialInsts addrs . Set [ addrs . PartialExpandedModule ] ) ( * Graph , tfdiags . Diagnostics ) {
var g Graph
var diags tfdiags . Diagnostics
Nick Fagerlund
2 years ago
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