command/views: Add reason to JSON planned change

Now that we have extra information about the reason for a given resource
action, include that in the JSON log output for planned changes.

command/views/json/change.go

@@ -10,6 +10,7 @@ func NewResourceInstanceChange(change *plans.ResourceInstanceChangeSrc) *Resourc
 	c := &ResourceInstanceChange{
 		Resource: newResourceAddr(change.Addr),
 		Action:   changeAction(change.Action),
+		Reason:   changeReason(change.ActionReason),
 	}
 
 	return c
@@ -18,6 +19,7 @@ func NewResourceInstanceChange(change *plans.ResourceInstanceChangeSrc) *Resourc
 type ResourceInstanceChange struct {
 	Resource ResourceAddr `json:"resource"`
 	Action   ChangeAction `json:"action"`
+	Reason   ChangeReason `json:"reason,omitempty"`
 }
 
 func (c *ResourceInstanceChange) String() string {
@@ -53,3 +55,31 @@ func changeAction(action plans.Action) ChangeAction {
 		return ActionNoOp
 	}
 }
+
+type ChangeReason string
+
+const (
+	ReasonNone         ChangeReason = ""
+	ReasonTainted      ChangeReason = "tainted"
+	ReasonRequested    ChangeReason = "requested"
+	ReasonCannotUpdate ChangeReason = "cannot_update"
+	ReasonUnknown      ChangeReason = "unknown"
+)
+
+func changeReason(reason plans.ResourceInstanceChangeActionReason) ChangeReason {
+	switch reason {
+	case plans.ResourceInstanceChangeNoReason:
+		return ReasonNone
+	case plans.ResourceInstanceReplaceBecauseTainted:
+		return ReasonTainted
+	case plans.ResourceInstanceReplaceByRequest:
+		return ReasonRequested
+	case plans.ResourceInstanceReplaceBecauseCannotUpdate:
+		return ReasonCannotUpdate
+	default:
+		// This should never happen, but there's no good way to guarantee
+		// exhaustive handling of the enum, so a generic fall back is better
+		// than a misleading result or a panic
+		return ReasonUnknown
+	}
+}

command/views/operation_test.go

@@ -433,9 +433,16 @@ func TestOperationJSON_plannedChange(t *testing.T) {
 	boop := addrs.Resource{Mode: addrs.ManagedResourceMode, Type: "test_instance", Name: "boop"}
 	derp := addrs.Resource{Mode: addrs.DataResourceMode, Type: "test_source", Name: "derp"}
 
+	// Replace requested by user
+	v.PlannedChange(&plans.ResourceInstanceChangeSrc{
+		Addr:         boop.Instance(addrs.IntKey(0)).Absolute(root),
+		ChangeSrc:    plans.ChangeSrc{Action: plans.DeleteThenCreate},
+		ActionReason: plans.ResourceInstanceReplaceByRequest,
+	})
+
 	// Simple create
 	v.PlannedChange(&plans.ResourceInstanceChangeSrc{
-		Addr:      boop.Instance(addrs.IntKey(0)).Absolute(root),
+		Addr:      boop.Instance(addrs.IntKey(1)).Absolute(root),
 		ChangeSrc: plans.ChangeSrc{Action: plans.Create},
 	})
 
@@ -445,15 +452,16 @@ func TestOperationJSON_plannedChange(t *testing.T) {
 		ChangeSrc: plans.ChangeSrc{Action: plans.Delete},
 	})
 
-	// Expect one message only, as the data source deletion should be a no-op
+	// Expect only two messages, as the data source deletion should be a no-op
 	want := []map[string]interface{}{
 		{
 			"@level":   "info",
-			"@message": "test_instance.boop[0]: Plan to create",
+			"@message": "test_instance.boop[0]: Plan to replace",
 			"@module":  "terraform.ui",
 			"type":     "planned_change",
 			"change": map[string]interface{}{
-				"action": "create",
+				"action": "replace",
+				"reason": "requested",
 				"resource": map[string]interface{}{
 					"addr":             `test_instance.boop[0]`,
 					"implied_provider": "test",
@@ -465,6 +473,24 @@ func TestOperationJSON_plannedChange(t *testing.T) {
 				},
 			},
 		},
+		{
+			"@level":   "info",
+			"@message": "test_instance.boop[1]: Plan to create",
+			"@module":  "terraform.ui",
+			"type":     "planned_change",
+			"change": map[string]interface{}{
+				"action": "create",
+				"resource": map[string]interface{}{
+					"addr":             `test_instance.boop[1]`,
+					"implied_provider": "test",
+					"module":           "",
+					"resource":         `test_instance.boop[1]`,
+					"resource_key":     float64(1),
+					"resource_name":    "boop",
+					"resource_type":    "test_instance",
+				},
+			},
+		},
 	}
 
 	testJSONViewOutputEquals(t, done(t).Stdout(), want)