terraform: only include variables in graph if count of a resource

depends

terraform/graph_config_node_output.go

@@ -62,7 +62,7 @@ func (n *GraphNodeConfigOutput) Proxy() bool {
 }
 
 // GraphNodeDestroyEdgeInclude impl.
-func (n *GraphNodeConfigOutput) DestroyEdgeInclude(bool) bool {
+func (n *GraphNodeConfigOutput) DestroyEdgeInclude(dag.Vertex) bool {
 	return false
 }
 

terraform/graph_config_node_resource.go

@@ -9,6 +9,12 @@ import (
 	"github.com/hashicorp/terraform/dot"
 )
 
+// GraphNodeCountDependent is implemented by resources for giving only
+// the dependencies they have from the "count" field.
+type GraphNodeCountDependent interface {
+	CountDependentOn() []string
+}
+
 // GraphNodeConfigResource represents a resource within the config graph.
 type GraphNodeConfigResource struct {
 	Resource *config.Resource
@@ -31,6 +37,18 @@ func (n *GraphNodeConfigResource) DependableName() []string {
 	return []string{n.Resource.Id()}
 }
 
+// GraphNodeCountDependent impl.
+func (n *GraphNodeConfigResource) CountDependentOn() []string {
+	result := make([]string, 0, len(n.Resource.RawCount.Variables))
+	for _, v := range n.Resource.RawCount.Variables {
+		if vn := varNameForVar(v); vn != "" {
+			result = append(result, vn)
+		}
+	}
+
+	return result
+}
+
 // GraphNodeDependent impl.
 func (n *GraphNodeConfigResource) DependentOn() []string {
 	result := make([]string, len(n.Resource.DependsOn),

terraform/graph_config_node_variable.go

@@ -56,14 +56,23 @@ func (n *GraphNodeConfigVariable) VariableName() string {
 }
 
 // GraphNodeDestroyEdgeInclude impl.
-func (n *GraphNodeConfigVariable) DestroyEdgeInclude(full bool) bool {
-	// Don't include variables as dependencies in destroy nodes.
-	// Destroy nodes don't interpolate anyways and this has a possibility
-	// to create cycles. See GH-1835
-	//
-	// We include the variable on non-full destroys because it might
-	// be used for count interpolation.
-	return !full
+func (n *GraphNodeConfigVariable) DestroyEdgeInclude(v dag.Vertex) bool {
+	// Only include this variable in a destroy edge if the source vertex
+	// "v" has a count dependency on this variable.
+	cv, ok := v.(GraphNodeCountDependent)
+	if !ok {
+		return false
+	}
+
+	for _, d := range cv.CountDependentOn() {
+		for _, d2 := range n.DependableName() {
+			if d == d2 {
+				return true
+			}
+		}
+	}
+
+	return false
 }
 
 // GraphNodeProxy impl.

terraform/transform_destroy.go

@@ -49,7 +49,7 @@ type GraphNodeDestroyPrunable interface {
 // as an edge within the destroy graph. This is usually done because it
 // might cause unnecessary cycles.
 type GraphNodeDestroyEdgeInclude interface {
-	DestroyEdgeInclude(bool) bool
+	DestroyEdgeInclude(dag.Vertex) bool
 }
 
 // DestroyTransformer is a GraphTransformer that creates the destruction
@@ -114,7 +114,7 @@ func (t *DestroyTransformer) transform(
 			// If this thing specifically requests to not be depended on
 			// by destroy nodes, then don't.
 			if i, ok := edgeRaw.(GraphNodeDestroyEdgeInclude); ok &&
-				!i.DestroyEdgeInclude(t.FullDestroy) {
+				!i.DestroyEdgeInclude(v) {
 				continue
 			}