Merge pull request #25544 from hashicorp/jbardin/resource-state

don't store an entire Resource's state in each ResourceInstance

terraform/node_resource_abstract.go

@@ -101,11 +101,14 @@ type NodeAbstractResourceInstance struct {
 	NodeAbstractResource
 	Addr addrs.AbsResourceInstance
 
-	// The fields below will be automatically set using the Attach
-	// interfaces if you're running those transforms, but also be explicitly
-	// set if you already have that information.
-	ResourceState *states.Resource
-	Dependencies  []addrs.ConfigResource
+	// These are set via the AttachState method.
+	instanceState *states.ResourceInstance
+	// storedProviderConfig is the provider address retrieved from the
+	// state, but since it is only stored in the whole Resource rather than the
+	// ResourceInstance, we extract it out here.
+	storedProviderConfig addrs.AbsProviderConfig
+
+	Dependencies []addrs.ConfigResource
 }
 
 var (
@@ -287,11 +290,9 @@ func dottedInstanceAddr(tr addrs.ResourceInstance) string {
 
 // StateDependencies returns the dependencies saved in the state.
 func (n *NodeAbstractResourceInstance) StateDependencies() []addrs.ConfigResource {
-	if rs := n.ResourceState; rs != nil {
-		if s := rs.Instance(n.Addr.Resource.Key); s != nil {
-			if s.Current != nil {
-				return s.Current.Dependencies
-			}
+	if s := n.instanceState; s != nil {
+		if s.Current != nil {
+			return s.Current.Dependencies
 		}
 	}
 
@@ -339,12 +340,12 @@ func (n *NodeAbstractResourceInstance) ProvidedBy() (addrs.ProviderConfig, bool)
 		}, false
 	}
 
-	// If we have state, then we will use the provider from there
-	if n.ResourceState != nil {
+	// See if we have a valid provider config from the state.
+	if n.storedProviderConfig.Provider.Type != "" {
 		// An address from the state must match exactly, since we must ensure
 		// we refresh/destroy a resource with the same provider configuration
 		// that created it.
-		return n.ResourceState.ProviderConfig, true
+		return n.storedProviderConfig, true
 	}
 
 	// No provider configuration found; return a default address
@@ -410,7 +411,12 @@ func (n *NodeAbstractResource) AttachResourceDependencies(deps []addrs.ConfigRes
 
 // GraphNodeAttachResourceState
 func (n *NodeAbstractResourceInstance) AttachResourceState(s *states.Resource) {
-	n.ResourceState = s
+	if s == nil {
+		log.Printf("[WARN] attaching nil state to %s", n.Addr)
+		return
+	}
+	n.instanceState = s.Instance(n.Addr.Resource.Key)
+	n.storedProviderConfig = s.ProviderConfig
 }
 
 // GraphNodeAttachResourceConfig

terraform/node_resource_destroy.go

@@ -63,11 +63,9 @@ func (n *NodeDestroyResourceInstance) CreateBeforeDestroy() bool {
 	}
 
 	// Otherwise check the state for a stored destroy order
-	if rs := n.ResourceState; rs != nil {
-		if s := rs.Instance(n.Addr.Resource.Key); s != nil {
-			if s.Current != nil {
-				return s.Current.CreateBeforeDestroy
-			}
+	if s := n.instanceState; s != nil {
+		if s.Current != nil {
+			return s.Current.CreateBeforeDestroy
 		}
 	}
 
@@ -134,11 +132,7 @@ func (n *NodeDestroyResourceInstance) EvalTree() EvalNode {
 	addr := n.ResourceInstanceAddr()
 
 	// Get our state
-	rs := n.ResourceState
-	var is *states.ResourceInstance
-	if rs != nil {
-		is = rs.Instance(n.Addr.Resource.Key)
-	}
+	is := n.instanceState
 	if is == nil {
 		log.Printf("[WARN] NodeDestroyResourceInstance for %s with no state", addr)
 	}

terraform/node_resource_refresh.go

@@ -215,7 +215,7 @@ func (n *NodeRefreshableManagedResourceInstance) EvalTree() EvalNode {
 	// Eval info is different depending on what kind of resource this is
 	switch addr.Resource.Resource.Mode {
 	case addrs.ManagedResourceMode:
-		if n.ResourceState == nil {
+		if n.instanceState == nil {
 			log.Printf("[TRACE] NodeRefreshableManagedResourceInstance: %s has no existing state to refresh", addr)
 			return n.evalTreeManagedResourceNoState()
 		}
@@ -253,7 +253,7 @@ func (n *NodeRefreshableManagedResourceInstance) evalTreeManagedResource() EvalN
 
 	// This happened during initial development. All known cases were
 	// fixed and tested but as a sanity check let's assert here.
-	if n.ResourceState == nil {
+	if n.instanceState == nil {
 		err := fmt.Errorf(
 			"No resource state attached for addr: %s\n\n"+
 				"This is a bug. Please report this to Terraform with your configuration\n"+