evaltree refactor

terraform/node_resource_abstract.go

@@ -498,6 +498,8 @@ func (n *NodeAbstractResource) WriteResourceState(ctx EvalContext, addr addrs.Ab
 	return nil
 }
 
+// ReadResourceInstanceState reads the current object for a specific instance in
+// the state.
 func (n *NodeAbstractResource) ReadResourceInstanceState(ctx EvalContext, addr addrs.AbsResourceInstance) (*states.ResourceInstanceObject, error) {
 	provider, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
 
@@ -540,31 +542,6 @@ func (n *NodeAbstractResource) ReadResourceInstanceState(ctx EvalContext, addr a
 	return obj, nil
 }
 
-// CheckPreventDestroy returns an error if a resource has PreventDestroy
-// configured and the diff would destroy the resource.
-func (n *NodeAbstractResource) CheckPreventDestroy(addr addrs.AbsResourceInstance, change *plans.ResourceInstanceChange) error {
-	if change == nil || n.Config == nil || n.Config.Managed == nil {
-		return nil
-	}
-	preventDestroy := n.Config.Managed.PreventDestroy
-
-	if (change.Action == plans.Delete || change.Action.IsReplace()) && preventDestroy {
-		var diags tfdiags.Diagnostics
-		diags = diags.Append(&hcl.Diagnostic{
-			Severity: hcl.DiagError,
-			Summary:  "Instance cannot be destroyed",
-			Detail: fmt.Sprintf(
-				"Resource %s has lifecycle.prevent_destroy set, but the plan calls for this resource to be destroyed. To avoid this error and continue with the plan, either disable lifecycle.prevent_destroy or reduce the scope of the plan using the -target flag.",
-				addr,
-			),
-			Subject: &n.Config.DeclRange,
-		})
-		return diags.Err()
-	}
-
-	return nil
-}
-
 // ReadDiff returns the planned change for a particular resource instance
 // object.
 func (n *NodeAbstractResourceInstance) ReadDiff(ctx EvalContext, providerSchema *ProviderSchema) (*plans.ResourceInstanceChange, error) {
@@ -594,6 +571,30 @@ func (n *NodeAbstractResourceInstance) ReadDiff(ctx EvalContext, providerSchema
 	return change, nil
 }
 
+func (n *NodeAbstractResourceInstance) checkPreventDestroy(change *plans.ResourceInstanceChange) error {
+	if change == nil || n.Config == nil || n.Config.Managed == nil {
+		return nil
+	}
+
+	preventDestroy := n.Config.Managed.PreventDestroy
+
+	if (change.Action == plans.Delete || change.Action.IsReplace()) && preventDestroy {
+		var diags tfdiags.Diagnostics
+		diags = diags.Append(&hcl.Diagnostic{
+			Severity: hcl.DiagError,
+			Summary:  "Instance cannot be destroyed",
+			Detail: fmt.Sprintf(
+				"Resource %s has lifecycle.prevent_destroy set, but the plan calls for this resource to be destroyed. To avoid this error and continue with the plan, either disable lifecycle.prevent_destroy or reduce the scope of the plan using the -target flag.",
+				n.Addr.String(),
+			),
+			Subject: &n.Config.DeclRange,
+		})
+		return diags.Err()
+	}
+
+	return nil
+}
+
 // graphNodesAreResourceInstancesInDifferentInstancesOfSameModule is an
 // annoyingly-task-specific helper function that returns true if and only if
 // the following conditions hold:

terraform/node_resource_plan_destroy.go

@@ -1,12 +1,8 @@
 package terraform
 
 import (
-	"fmt"
-
 	"github.com/hashicorp/terraform/addrs"
-	"github.com/hashicorp/terraform/dag"
 	"github.com/hashicorp/terraform/plans"
-	"github.com/hashicorp/terraform/providers"
 	"github.com/hashicorp/terraform/states"
 )
 
@@ -25,7 +21,7 @@ var (
 	_ GraphNodeResourceInstance     = (*NodePlanDestroyableResourceInstance)(nil)
 	_ GraphNodeAttachResourceConfig = (*NodePlanDestroyableResourceInstance)(nil)
 	_ GraphNodeAttachResourceState  = (*NodePlanDestroyableResourceInstance)(nil)
-	_ GraphNodeEvalable             = (*NodePlanDestroyableResourceInstance)(nil)
+	_ GraphNodeExecutable           = (*NodePlanDestroyableResourceInstance)(nil)
 	_ GraphNodeProviderConsumer     = (*NodePlanDestroyableResourceInstance)(nil)
 )
 
@@ -36,53 +32,46 @@ func (n *NodePlanDestroyableResourceInstance) DestroyAddr() *addrs.AbsResourceIn
 }
 
 // GraphNodeEvalable
-func (n *NodePlanDestroyableResourceInstance) EvalTree() EvalNode {
+func (n *NodePlanDestroyableResourceInstance) Execute(ctx EvalContext, op walkOperation) error {
 	addr := n.ResourceInstanceAddr()
 
 	// Declare a bunch of variables that are used for state during
 	// evaluation. These are written to by address in the EvalNodes we
 	// declare below.
-	var provider providers.Interface
-	var providerSchema *ProviderSchema
 	var change *plans.ResourceInstanceChange
 	var state *states.ResourceInstanceObject
 
-	if n.ResolvedProvider.Provider.Type == "" {
+	_, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
-		// Should never happen; indicates that the graph was not constructed
+	if err != nil {
-		// correctly since we didn't get our provider attached.
+		return err
-		panic(fmt.Sprintf("%T %q was not assigned a resolved provider", n, dag.VertexName(n)))
 	}
 
-	return &EvalSequence{
+	state, err = n.ReadResourceInstanceState(ctx, addr)
-		Nodes: []EvalNode{
+	if err != nil {
-			&EvalGetProvider{
+		return err
-				Addr:   n.ResolvedProvider,
+	}
-				Output: &provider,
-				Schema: &providerSchema,
-			},
-			&EvalReadState{
-				Addr:           addr.Resource,
-				Provider:       &provider,
-				ProviderSchema: &providerSchema,
 
-				Output: &state,
+	diffDestroy := &EvalDiffDestroy{
-			},
-			&EvalDiffDestroy{
 		Addr:         addr.Resource,
 		ProviderAddr: n.ResolvedProvider,
 		State:        &state,
 		Output:       &change,
-			},
+	}
-			&EvalCheckPreventDestroy{
+	_, err = diffDestroy.Eval(ctx)
-				Addr:   addr.Resource,
+	if err != nil {
-				Config: n.Config,
+		return err
-				Change: &change,
+	}
-			},
+
-			&EvalWriteDiff{
+	err = n.checkPreventDestroy(change)
+	if err != nil {
+		return err
+	}
+
+	writeDiff := &EvalWriteDiff{
 		Addr:           addr.Resource,
 		ProviderSchema: &providerSchema,
 		Change:         &change,
-			},
-		},
 	}
+	_, err = writeDiff.Eval(ctx)
+	return err
 }

terraform/node_resource_plan_instance.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 
 	"github.com/hashicorp/terraform/plans"
-	"github.com/hashicorp/terraform/providers"
 	"github.com/hashicorp/terraform/states"
 
 	"github.com/hashicorp/terraform/addrs"
@@ -27,53 +26,52 @@ var (
 	_ GraphNodeResourceInstance     = (*NodePlannableResourceInstance)(nil)
 	_ GraphNodeAttachResourceConfig = (*NodePlannableResourceInstance)(nil)
 	_ GraphNodeAttachResourceState  = (*NodePlannableResourceInstance)(nil)
-	_ GraphNodeEvalable             = (*NodePlannableResourceInstance)(nil)
+	_ GraphNodeExecutable           = (*NodePlannableResourceInstance)(nil)
 )
 
 // GraphNodeEvalable
-func (n *NodePlannableResourceInstance) EvalTree() EvalNode {
+func (n *NodePlannableResourceInstance) Execute(ctx EvalContext, op walkOperation) error {
 	addr := n.ResourceInstanceAddr()
 
 	// Eval info is different depending on what kind of resource this is
 	switch addr.Resource.Resource.Mode {
 	case addrs.ManagedResourceMode:
-		return n.evalTreeManagedResource(addr)
+		return n.managedResourceExecute(ctx, n.skipRefresh)
 	case addrs.DataResourceMode:
-		return n.evalTreeDataResource(addr)
+		return n.dataResourceExecute(ctx)
 	default:
 		panic(fmt.Errorf("unsupported resource mode %s", n.Config.Mode))
 	}
 }
 
-func (n *NodePlannableResourceInstance) evalTreeDataResource(addr addrs.AbsResourceInstance) EvalNode {
+func (n *NodePlannableResourceInstance) dataResourceExecute(ctx EvalContext) error {
 	config := n.Config
-	var provider providers.Interface
+	addr := n.ResourceInstanceAddr()
-	var providerSchema *ProviderSchema
+
 	var change *plans.ResourceInstanceChange
 	var state *states.ResourceInstanceObject
 
-	return &EvalSequence{
+	provider, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
-		Nodes: []EvalNode{
+	if err != nil {
-			&EvalGetProvider{
+		return err
-				Addr:   n.ResolvedProvider,
+	}
-				Output: &provider,
-				Schema: &providerSchema,
-			},
 
-			&EvalReadState{
+	state, err = n.ReadResourceInstanceState(ctx, addr)
-				Addr:           addr.Resource,
+	if err != nil {
-				Provider:       &provider,
+		return err
-				ProviderSchema: &providerSchema,
+	}
-				Output:         &state,
-			},
 
-			&EvalValidateSelfRef{
+	validateSelfRef := &EvalValidateSelfRef{
 		Addr:           addr.Resource,
 		Config:         config.Config,
 		ProviderSchema: &providerSchema,
-			},
+	}
+	_, err = validateSelfRef.Eval(ctx)
+	if err != nil {
+		return err
+	}
 
-			&evalReadDataPlan{
+	readDataPlan := &evalReadDataPlan{
 		evalReadData: evalReadData{
 			Addr:           addr.Resource,
 			Config:         n.Config,
@@ -85,76 +83,88 @@ func (n *NodePlannableResourceInstance) evalTreeDataResource(addr addrs.AbsResou
 			State:          &state,
 			dependsOn:      n.dependsOn,
 		},
-			},
+	}
+	_, err = readDataPlan.Eval(ctx)
+	if err != nil {
+		return err
+	}
 
 	// write the data source into both the refresh state and the
 	// working state
-			&EvalWriteState{
+	writeRefreshState := &EvalWriteState{
 		Addr:           addr.Resource,
 		ProviderAddr:   n.ResolvedProvider,
 		ProviderSchema: &providerSchema,
 		State:          &state,
 		targetState:    refreshState,
-			},
+	}
+	_, err = writeRefreshState.Eval(ctx)
+	if err != nil {
+		return err
+	}
 
-			&EvalWriteState{
+	writeState := &EvalWriteState{
 		Addr:           addr.Resource,
 		ProviderAddr:   n.ResolvedProvider,
 		ProviderSchema: &providerSchema,
 		State:          &state,
-			},
+	}
+	_, err = writeState.Eval(ctx)
+	if err != nil {
+		return err
+	}
 
-			&EvalWriteDiff{
+	writeDiff := &EvalWriteDiff{
 		Addr:           addr.Resource,
 		ProviderSchema: &providerSchema,
 		Change:         &change,
-			},
-		},
 	}
+	_, err = writeDiff.Eval(ctx)
+	return err
 }
 
-func (n *NodePlannableResourceInstance) evalTreeManagedResource(addr addrs.AbsResourceInstance) EvalNode {
+func (n *NodePlannableResourceInstance) managedResourceExecute(ctx EvalContext, skipRefresh bool) error {
 	config := n.Config
-	var provider providers.Interface
+	addr := n.ResourceInstanceAddr()
-	var providerSchema *ProviderSchema
+
 	var change *plans.ResourceInstanceChange
 	var instanceRefreshState *states.ResourceInstanceObject
 	var instancePlanState *states.ResourceInstanceObject
 
-	return &EvalSequence{
+	provider, providerSchema, err := GetProvider(ctx, n.ResolvedProvider)
-		Nodes: []EvalNode{
+	if err != nil {
-			&EvalGetProvider{
+		return err
-				Addr:   n.ResolvedProvider,
+	}
-				Output: &provider,
-				Schema: &providerSchema,
-			},
 
-			&EvalValidateSelfRef{
+	validateSelfRef := &EvalValidateSelfRef{
 		Addr:           addr.Resource,
 		Config:         config.Config,
 		ProviderSchema: &providerSchema,
-			},
+	}
+	_, err = validateSelfRef.Eval(ctx)
+	if err != nil {
+		return err
+	}
 
-			&EvalIf{
+	// Refresh, maybe
-				If: func(ctx EvalContext) (bool, error) {
+	if !skipRefresh {
-					return !n.skipRefresh, nil
+		instanceRefreshState, err = n.ReadResourceInstanceState(ctx, addr)
-				},
+		if err != nil {
-				Then: &EvalSequence{
+			return err
-					Nodes: []EvalNode{
+		}
-						// Refresh the instance
+
-						&EvalReadState{
+		refreshLifecycle := &EvalRefreshLifecycle{
-							Addr:           addr.Resource,
-							Provider:       &provider,
-							ProviderSchema: &providerSchema,
-							Output:         &instanceRefreshState,
-						},
-						&EvalRefreshLifecycle{
 			Addr:                     addr,
 			Config:                   n.Config,
 			State:                    &instanceRefreshState,
 			ForceCreateBeforeDestroy: n.ForceCreateBeforeDestroy,
-						},
+		}
-						&EvalRefresh{
+		_, err = refreshLifecycle.Eval(ctx)
+		if err != nil {
+			return err
+		}
+
+		refresh := &EvalRefresh{
 			Addr:           addr.Resource,
 			ProviderAddr:   n.ResolvedProvider,
 			Provider:       &provider,
@@ -162,21 +172,28 @@ func (n *NodePlannableResourceInstance) evalTreeManagedResource(addr addrs.AbsRe
 			ProviderSchema: &providerSchema,
 			State:          &instanceRefreshState,
 			Output:         &instanceRefreshState,
-						},
+		}
-						&EvalWriteState{
+		_, err = refresh.Eval(ctx)
+		if err != nil {
+			return err
+		}
+
+		writeRefreshState := &EvalWriteState{
 			Addr:           addr.Resource,
 			ProviderAddr:   n.ResolvedProvider,
-							State:          &instanceRefreshState,
 			ProviderSchema: &providerSchema,
+			State:          &instanceRefreshState,
 			targetState:    refreshState,
 			Dependencies:   &n.Dependencies,
-						},
+		}
-					},
+		_, err = writeRefreshState.Eval(ctx)
-				},
+		if err != nil {
-			},
+			return err
+		}
+	}
 
 	// Plan the instance
-			&EvalDiff{
+	diff := &EvalDiff{
 		Addr:                addr.Resource,
 		Config:              n.Config,
 		CreateBeforeDestroy: n.ForceCreateBeforeDestroy,
@@ -187,23 +204,33 @@ func (n *NodePlannableResourceInstance) evalTreeManagedResource(addr addrs.AbsRe
 		State:               &instanceRefreshState,
 		OutputChange:        &change,
 		OutputState:         &instancePlanState,
-			},
+	}
-			&EvalCheckPreventDestroy{
+	_, err = diff.Eval(ctx)
-				Addr:   addr.Resource,
+	if err != nil {
-				Config: n.Config,
+		return err
-				Change: &change,
+	}
-			},
+
-			&EvalWriteState{
+	err = n.checkPreventDestroy(change)
+	if err != nil {
+		return err
+	}
+
+	writeState := &EvalWriteState{
 		Addr:           addr.Resource,
 		ProviderAddr:   n.ResolvedProvider,
 		State:          &instancePlanState,
 		ProviderSchema: &providerSchema,
-			},
+	}
-			&EvalWriteDiff{
+	_, err = writeState.Eval(ctx)
+	if err != nil {
+		return err
+	}
+
+	writeDiff := &EvalWriteDiff{
 		Addr:           addr.Resource,
 		ProviderSchema: &providerSchema,
 		Change:         &change,
-			},
-		},
 	}
+	_, err = writeDiff.Eval(ctx)
+	return err
 }

terraform/node_resource_plan_orphan.go

@@ -57,7 +57,7 @@ func (n *NodePlannableResourceInstanceOrphan) Execute(ctx EvalContext, op walkOp
 		return err
 	}
 
-	err = n.CheckPreventDestroy(addr, change)
+	err = n.checkPreventDestroy(change)
 	if err != nil {
 		return err
 	}