json-output: Config-driven move support in JSON UI

Add previous address information to the `planned_change` and
`resource_drift` messages for the streaming JSON UI output of plan and
apply operations.

Here we also add a "move" action value to the `change` object of these
messages, to represent a move-only operation.

As part of this work we also simplify this code to use the plan's
DriftedResources values instead of recomputing the drift from state.

internal/command/views/json/change.go

@@ -12,12 +12,20 @@ func NewResourceInstanceChange(change *plans.ResourceInstanceChangeSrc) *Resourc
 		Action:   changeAction(change.Action),
 		Reason:   changeReason(change.ActionReason),
 	}
+	if !change.Addr.Equal(change.PrevRunAddr) {
+		if c.Action == ActionNoOp {
+			c.Action = ActionMove
+		}
+		pr := newResourceAddr(change.PrevRunAddr)
+		c.PreviousResource = &pr
+	}
 
 	return c
 }
 
 type ResourceInstanceChange struct {
 	Resource         ResourceAddr  `json:"resource"`
+	PreviousResource *ResourceAddr `json:"previous_resource,omitempty"`
 	Action           ChangeAction  `json:"action"`
 	Reason           ChangeReason  `json:"reason,omitempty"`
 }
@@ -30,6 +38,7 @@ type ChangeAction string
 
 const (
 	ActionNoOp    ChangeAction = "noop"
+	ActionMove    ChangeAction = "move"
 	ActionCreate  ChangeAction = "create"
 	ActionRead    ChangeAction = "read"
 	ActionUpdate  ChangeAction = "update"

internal/command/views/json_view_test.go

@@ -112,6 +112,7 @@ func TestJSONView_PlannedChange(t *testing.T) {
 	managed := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_instance", Name: "bar"}
 	cs := &plans.ResourceInstanceChangeSrc{
 		Addr:        managed.Instance(addrs.StringKey("boop")).Absolute(foo),
+		PrevRunAddr: managed.Instance(addrs.StringKey("boop")).Absolute(foo),
 		ChangeSrc: plans.ChangeSrc{
 			Action: plans.Create,
 		},
@@ -152,6 +153,7 @@ func TestJSONView_ResourceDrift(t *testing.T) {
 	managed := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_instance", Name: "bar"}
 	cs := &plans.ResourceInstanceChangeSrc{
 		Addr:        managed.Instance(addrs.StringKey("boop")).Absolute(foo),
+		PrevRunAddr: managed.Instance(addrs.StringKey("boop")).Absolute(foo),
 		ChangeSrc: plans.ChangeSrc{
 			Action: plans.Update,
 		},

internal/command/views/operation.go

@@ -3,7 +3,6 @@ package views
 import (
 	"bytes"
 	"fmt"
-	"sort"
 	"strings"
 
 	"github.com/hashicorp/terraform/internal/addrs"
@@ -11,11 +10,9 @@ import (
 	"github.com/hashicorp/terraform/internal/command/format"
 	"github.com/hashicorp/terraform/internal/command/views/json"
 	"github.com/hashicorp/terraform/internal/plans"
-	"github.com/hashicorp/terraform/internal/states"
 	"github.com/hashicorp/terraform/internal/states/statefile"
 	"github.com/hashicorp/terraform/internal/terraform"
 	"github.com/hashicorp/terraform/internal/tfdiags"
-	"github.com/zclconf/go-cty/cty"
 )
 
 type Operation interface {
@@ -163,10 +160,14 @@ func (v *OperationJSON) EmergencyDumpState(stateFile *statefile.File) error {
 // Log a change summary and a series of "planned" messages for the changes in
 // the plan.
 func (v *OperationJSON) Plan(plan *plans.Plan, schemas *terraform.Schemas) {
-	if err := v.resourceDrift(plan.PrevRunState, plan.PriorState, schemas); err != nil {
-		var diags tfdiags.Diagnostics
-		diags = diags.Append(err)
-		v.Diagnostics(diags)
+	for _, dr := range plan.DriftedResources {
+		// In refresh-only mode, we output all resources marked as drifted,
+		// including those which have moved without other changes. In other plan
+		// modes, move-only changes will be included in the planned changes, so
+		// we skip them here.
+		if dr.Action != plans.NoOp || plan.UIMode == plans.RefreshOnlyMode {
+			v.view.ResourceDrift(json.NewResourceInstanceChange(dr))
+		}
 	}
 
 	cs := &json.ChangeSummary{
@@ -189,7 +190,7 @@ func (v *OperationJSON) Plan(plan *plans.Plan, schemas *terraform.Schemas) {
 			cs.Remove++
 		}
 
-		if change.Action != plans.NoOp {
+		if change.Action != plans.NoOp || !change.Addr.Equal(change.PrevRunAddr) {
 			v.view.PlannedChange(json.NewResourceInstanceChange(change))
 		}
 	}
@@ -208,92 +209,6 @@ func (v *OperationJSON) Plan(plan *plans.Plan, schemas *terraform.Schemas) {
 	}
 }
 
-func (v *OperationJSON) resourceDrift(oldState, newState *states.State, schemas *terraform.Schemas) error {
-	if newState.ManagedResourcesEqual(oldState) {
-		// Nothing to do, because we only detect and report drift for managed
-		// resource instances.
-		return nil
-	}
-	var changes []*json.ResourceInstanceChange
-	for _, ms := range oldState.Modules {
-		for _, rs := range ms.Resources {
-			if rs.Addr.Resource.Mode != addrs.ManagedResourceMode {
-				// Drift reporting is only for managed resources
-				continue
-			}
-
-			provider := rs.ProviderConfig.Provider
-			for key, oldIS := range rs.Instances {
-				if oldIS.Current == nil {
-					// Not interested in instances that only have deposed objects
-					continue
-				}
-				addr := rs.Addr.Instance(key)
-				newIS := newState.ResourceInstance(addr)
-
-				schema, _ := schemas.ResourceTypeConfig(
-					provider,
-					addr.Resource.Resource.Mode,
-					addr.Resource.Resource.Type,
-				)
-				if schema == nil {
-					return fmt.Errorf("no schema found for %s (in provider %s)", addr, provider)
-				}
-				ty := schema.ImpliedType()
-
-				oldObj, err := oldIS.Current.Decode(ty)
-				if err != nil {
-					return fmt.Errorf("failed to decode previous run data for %s: %s", addr, err)
-				}
-
-				var newObj *states.ResourceInstanceObject
-				if newIS != nil && newIS.Current != nil {
-					newObj, err = newIS.Current.Decode(ty)
-					if err != nil {
-						return fmt.Errorf("failed to decode refreshed data for %s: %s", addr, err)
-					}
-				}
-
-				var oldVal, newVal cty.Value
-				oldVal = oldObj.Value
-				if newObj != nil {
-					newVal = newObj.Value
-				} else {
-					newVal = cty.NullVal(ty)
-				}
-
-				if oldVal.RawEquals(newVal) {
-					// No drift if the two values are semantically equivalent
-					continue
-				}
-
-				// We can only detect updates and deletes as drift.
-				action := plans.Update
-				if newVal.IsNull() {
-					action = plans.Delete
-				}
-
-				change := &plans.ResourceInstanceChangeSrc{
-					Addr: addr,
-					ChangeSrc: plans.ChangeSrc{
-						Action: action,
-					},
-				}
-				changes = append(changes, json.NewResourceInstanceChange(change))
-			}
-		}
-	}
-
-	// Sort the change structs lexically by address to give stable output
-	sort.Slice(changes, func(i, j int) bool { return changes[i].Resource.Addr < changes[j].Resource.Addr })
-
-	for _, change := range changes {
-		v.view.ResourceDrift(change)
-	}
-
-	return nil
-}
-
 func (v *OperationJSON) PlannedChange(change *plans.ResourceInstanceChangeSrc) {
 	if change.Action == plans.Delete && change.Addr.Resource.Resource.Mode == addrs.DataResourceMode {
 		// Avoid rendering data sources on deletion

internal/command/views/operation_test.go

@@ -480,27 +480,33 @@ func TestOperationJSON_plan(t *testing.T) {
 			Resources: []*plans.ResourceInstanceChangeSrc{
 				{
 					Addr:        boop.Instance(addrs.IntKey(0)).Absolute(root),
+					PrevRunAddr: boop.Instance(addrs.IntKey(0)).Absolute(root),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.CreateThenDelete},
 				},
 				{
 					Addr:        boop.Instance(addrs.IntKey(1)).Absolute(root),
+					PrevRunAddr: boop.Instance(addrs.IntKey(1)).Absolute(root),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.Create},
 				},
 				{
 					Addr:        boop.Instance(addrs.IntKey(0)).Absolute(vpc),
+					PrevRunAddr: boop.Instance(addrs.IntKey(0)).Absolute(vpc),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.Delete},
 				},
 				{
 					Addr:        beep.Instance(addrs.NoKey).Absolute(root),
+					PrevRunAddr: beep.Instance(addrs.NoKey).Absolute(root),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.DeleteThenCreate},
 				},
 				{
 					Addr:        beep.Instance(addrs.NoKey).Absolute(vpc),
+					PrevRunAddr: beep.Instance(addrs.NoKey).Absolute(vpc),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.Update},
 				},
 				// Data source deletion should not show up in the logs
 				{
 					Addr:        derp.Instance(addrs.NoKey).Absolute(root),
+					PrevRunAddr: derp.Instance(addrs.NoKey).Absolute(root),
 					ChangeSrc:   plans.ChangeSrc{Action: plans.Delete},
 				},
 			},
@@ -623,74 +629,175 @@ func TestOperationJSON_plan(t *testing.T) {
 	testJSONViewOutputEquals(t, done(t).Stdout(), want)
 }
 
-func TestOperationJSON_planDrift(t *testing.T) {
+func TestOperationJSON_planDriftWithMove(t *testing.T) {
 	streams, done := terminal.StreamsForTesting(t)
 	v := &OperationJSON{view: NewJSONView(NewView(streams))}
 
 	root := addrs.RootModuleInstance
 	boop := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "boop"}
 	beep := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "beep"}
-	derp := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "derp"}
+	blep := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "blep"}
+	honk := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "honk"}
 
 	plan := &plans.Plan{
+		UIMode: plans.NormalMode,
+		Changes: &plans.Changes{
+			Resources: []*plans.ResourceInstanceChangeSrc{
+				{
+					Addr:        honk.Instance(addrs.StringKey("bonk")).Absolute(root),
+					PrevRunAddr: honk.Instance(addrs.IntKey(0)).Absolute(root),
+					ChangeSrc:   plans.ChangeSrc{Action: plans.NoOp},
+				},
+			},
+		},
+		DriftedResources: []*plans.ResourceInstanceChangeSrc{
+			{
+				Addr:        beep.Instance(addrs.NoKey).Absolute(root),
+				PrevRunAddr: beep.Instance(addrs.NoKey).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.Delete},
+			},
+			{
+				Addr:        boop.Instance(addrs.NoKey).Absolute(root),
+				PrevRunAddr: blep.Instance(addrs.NoKey).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.Update},
+			},
+			// Move-only resource drift should not be present in normal mode plans
+			{
+				Addr:        honk.Instance(addrs.StringKey("bonk")).Absolute(root),
+				PrevRunAddr: honk.Instance(addrs.IntKey(0)).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.NoOp},
+			},
+		},
+	}
+	v.Plan(plan, testSchemas())
+
+	want := []map[string]interface{}{
+		// Drift detected: delete
+		{
+			"@level":   "info",
+			"@message": "test_resource.beep: Drift detected (delete)",
+			"@module":  "terraform.ui",
+			"type":     "resource_drift",
+			"change": map[string]interface{}{
+				"action": "delete",
+				"resource": map[string]interface{}{
+					"addr":             "test_resource.beep",
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         "test_resource.beep",
+					"resource_key":     nil,
+					"resource_name":    "beep",
+					"resource_type":    "test_resource",
+				},
+			},
+		},
+		// Drift detected: update with move
+		{
+			"@level":   "info",
+			"@message": "test_resource.boop: Drift detected (update)",
+			"@module":  "terraform.ui",
+			"type":     "resource_drift",
+			"change": map[string]interface{}{
+				"action": "update",
+				"resource": map[string]interface{}{
+					"addr":             "test_resource.boop",
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         "test_resource.boop",
+					"resource_key":     nil,
+					"resource_name":    "boop",
+					"resource_type":    "test_resource",
+				},
+				"previous_resource": map[string]interface{}{
+					"addr":             "test_resource.blep",
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         "test_resource.blep",
+					"resource_key":     nil,
+					"resource_name":    "blep",
+					"resource_type":    "test_resource",
+				},
+			},
+		},
+		// Move-only change
+		{
+			"@level":   "info",
+			"@message": `test_resource.honk["bonk"]: Plan to move`,
+			"@module":  "terraform.ui",
+			"type":     "planned_change",
+			"change": map[string]interface{}{
+				"action": "move",
+				"resource": map[string]interface{}{
+					"addr":             `test_resource.honk["bonk"]`,
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         `test_resource.honk["bonk"]`,
+					"resource_key":     "bonk",
+					"resource_name":    "honk",
+					"resource_type":    "test_resource",
+				},
+				"previous_resource": map[string]interface{}{
+					"addr":             `test_resource.honk[0]`,
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         `test_resource.honk[0]`,
+					"resource_key":     float64(0),
+					"resource_name":    "honk",
+					"resource_type":    "test_resource",
+				},
+			},
+		},
+		// No changes
+		{
+			"@level":   "info",
+			"@message": "Plan: 0 to add, 0 to change, 0 to destroy.",
+			"@module":  "terraform.ui",
+			"type":     "change_summary",
+			"changes": map[string]interface{}{
+				"operation": "plan",
+				"add":       float64(0),
+				"change":    float64(0),
+				"remove":    float64(0),
+			},
+		},
+	}
+
+	testJSONViewOutputEquals(t, done(t).Stdout(), want)
+}
+
+func TestOperationJSON_planDriftWithMoveRefreshOnly(t *testing.T) {
+	streams, done := terminal.StreamsForTesting(t)
+	v := &OperationJSON{view: NewJSONView(NewView(streams))}
+
+	root := addrs.RootModuleInstance
+	boop := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "boop"}
+	beep := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "beep"}
+	blep := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "blep"}
+	honk := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_resource", Name: "honk"}
+
+	plan := &plans.Plan{
+		UIMode: plans.RefreshOnlyMode,
 		Changes: &plans.Changes{
 			Resources: []*plans.ResourceInstanceChangeSrc{},
 		},
-		PrevRunState: states.BuildState(func(state *states.SyncState) {
-			// Update
-			state.SetResourceInstanceCurrent(
-				boop.Instance(addrs.NoKey).Absolute(root),
-				&states.ResourceInstanceObjectSrc{
-					Status:    states.ObjectReady,
-					AttrsJSON: []byte(`{"foo":"bar"}`),
+		DriftedResources: []*plans.ResourceInstanceChangeSrc{
+			{
+				Addr:        beep.Instance(addrs.NoKey).Absolute(root),
+				PrevRunAddr: beep.Instance(addrs.NoKey).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.Delete},
 			},
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-			// Delete
-			state.SetResourceInstanceCurrent(
-				beep.Instance(addrs.NoKey).Absolute(root),
-				&states.ResourceInstanceObjectSrc{
-					Status:    states.ObjectReady,
-					AttrsJSON: []byte(`{"foo":"boop"}`),
+			{
+				Addr:        boop.Instance(addrs.NoKey).Absolute(root),
+				PrevRunAddr: blep.Instance(addrs.NoKey).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.Update},
 			},
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-			// No-op
-			state.SetResourceInstanceCurrent(
-				derp.Instance(addrs.NoKey).Absolute(root),
-				&states.ResourceInstanceObjectSrc{
-					Status:    states.ObjectReady,
-					AttrsJSON: []byte(`{"foo":"boop"}`),
+			// Move-only resource drift should be present in refresh-only plans
+			{
+				Addr:        honk.Instance(addrs.StringKey("bonk")).Absolute(root),
+				PrevRunAddr: honk.Instance(addrs.IntKey(0)).Absolute(root),
+				ChangeSrc:   plans.ChangeSrc{Action: plans.NoOp},
 			},
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-		}),
-		PriorState: states.BuildState(func(state *states.SyncState) {
-			// Update
-			state.SetResourceInstanceCurrent(
-				boop.Instance(addrs.NoKey).Absolute(root),
-				&states.ResourceInstanceObjectSrc{
-					Status:    states.ObjectReady,
-					AttrsJSON: []byte(`{"foo":"baz"}`),
 		},
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-			// Delete
-			state.SetResourceInstanceCurrent(
-				beep.Instance(addrs.NoKey).Absolute(root),
-				nil,
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-			// No-op
-			state.SetResourceInstanceCurrent(
-				derp.Instance(addrs.NoKey).Absolute(root),
-				&states.ResourceInstanceObjectSrc{
-					Status:    states.ObjectReady,
-					AttrsJSON: []byte(`{"foo":"boop"}`),
-				},
-				root.ProviderConfigDefault(addrs.NewDefaultProvider("test")),
-			)
-		}),
 	}
 	v.Plan(plan, testSchemas())
 
@@ -731,6 +838,43 @@ func TestOperationJSON_planDrift(t *testing.T) {
 					"resource_name":    "boop",
 					"resource_type":    "test_resource",
 				},
+				"previous_resource": map[string]interface{}{
+					"addr":             "test_resource.blep",
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         "test_resource.blep",
+					"resource_key":     nil,
+					"resource_name":    "blep",
+					"resource_type":    "test_resource",
+				},
+			},
+		},
+		// Drift detected: Move-only change
+		{
+			"@level":   "info",
+			"@message": `test_resource.honk["bonk"]: Drift detected (move)`,
+			"@module":  "terraform.ui",
+			"type":     "resource_drift",
+			"change": map[string]interface{}{
+				"action": "move",
+				"resource": map[string]interface{}{
+					"addr":             `test_resource.honk["bonk"]`,
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         `test_resource.honk["bonk"]`,
+					"resource_key":     "bonk",
+					"resource_name":    "honk",
+					"resource_type":    "test_resource",
+				},
+				"previous_resource": map[string]interface{}{
+					"addr":             `test_resource.honk[0]`,
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         `test_resource.honk[0]`,
+					"resource_key":     float64(0),
+					"resource_name":    "honk",
+					"resource_type":    "test_resource",
+				},
 			},
 		},
 		// No changes
@@ -846,6 +990,7 @@ func TestOperationJSON_plannedChange(t *testing.T) {
 	// Replace requested by user
 	v.PlannedChange(&plans.ResourceInstanceChangeSrc{
 		Addr:         boop.Instance(addrs.IntKey(0)).Absolute(root),
+		PrevRunAddr:  boop.Instance(addrs.IntKey(0)).Absolute(root),
 		ChangeSrc:    plans.ChangeSrc{Action: plans.DeleteThenCreate},
 		ActionReason: plans.ResourceInstanceReplaceByRequest,
 	})
@@ -853,12 +998,14 @@ func TestOperationJSON_plannedChange(t *testing.T) {
 	// Simple create
 	v.PlannedChange(&plans.ResourceInstanceChangeSrc{
 		Addr:        boop.Instance(addrs.IntKey(1)).Absolute(root),
+		PrevRunAddr: boop.Instance(addrs.IntKey(1)).Absolute(root),
 		ChangeSrc:   plans.ChangeSrc{Action: plans.Create},
 	})
 
 	// Data source deletion
 	v.PlannedChange(&plans.ResourceInstanceChangeSrc{
 		Addr:        derp.Instance(addrs.NoKey).Absolute(root),
+		PrevRunAddr: derp.Instance(addrs.NoKey).Absolute(root),
 		ChangeSrc:   plans.ChangeSrc{Action: plans.Delete},
 	})
 

website/docs/internals/machine-readable-ui.html.md

@@ -124,7 +124,8 @@ This message does not include details about the exact changes which caused the c
 At the end of a plan or before an apply, Terraform will emit a `planned_change` message for each resource which has changes to apply. This message has an embedded `change` object with the following keys:
 
 - `resource`: object describing the address of the resource to be changed; see [resource object](#resource-object) below for details
-- `action`: the action planned to be taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`.
+- `previous_resource`: object describing the previous address of the resource, if this change includes a configuration-driven move
+- `action`: the action planned to be taken for the resource. Values: `noop`, `create`, `read`, `update`, `replace`, `delete`, `move`.
 - `reason`: an optional reason for the change, currently only used when the action is `replace`. Values:
     - `tainted`: resource was marked as tainted
     - `requested`: user requested that the resource be replaced, for example via the `-replace` plan flag