Merge pull request #29649 from hashicorp/alisdair/json-ui-exhaustiveness

json-output: Add change reasons to explain deletes

internal/command/views/json/change.go

@@ -73,6 +73,12 @@ const (
 	ReasonRequested    ChangeReason = "requested"
 	ReasonCannotUpdate ChangeReason = "cannot_update"
 	ReasonUnknown      ChangeReason = "unknown"
+
+	ReasonDeleteBecauseNoResourceConfig ChangeReason = "delete_because_no_resource_config"
+	ReasonDeleteBecauseWrongRepetition  ChangeReason = "delete_because_wrong_repetition"
+	ReasonDeleteBecauseCountIndex       ChangeReason = "delete_because_count_index"
+	ReasonDeleteBecauseEachKey          ChangeReason = "delete_because_each_key"
+	ReasonDeleteBecauseNoModule         ChangeReason = "delete_because_no_module"
 )
 
 func changeReason(reason plans.ResourceInstanceChangeActionReason) ChangeReason {
@@ -85,6 +91,16 @@ func changeReason(reason plans.ResourceInstanceChangeActionReason) ChangeReason
 		return ReasonRequested
 	case plans.ResourceInstanceReplaceBecauseCannotUpdate:
 		return ReasonCannotUpdate
+	case plans.ResourceInstanceDeleteBecauseNoResourceConfig:
+		return ReasonDeleteBecauseNoResourceConfig
+	case plans.ResourceInstanceDeleteBecauseWrongRepetition:
+		return ReasonDeleteBecauseWrongRepetition
+	case plans.ResourceInstanceDeleteBecauseCountIndex:
+		return ReasonDeleteBecauseCountIndex
+	case plans.ResourceInstanceDeleteBecauseEachKey:
+		return ReasonDeleteBecauseEachKey
+	case plans.ResourceInstanceDeleteBecauseNoModule:
+		return ReasonDeleteBecauseNoModule
 	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

internal/command/views/json/hook.go

@@ -314,6 +314,10 @@ func startActionVerb(action plans.Action) string {
 		// This is not currently possible to reach, as we receive separate
 		// passes for create and delete
 		return "Replacing"
+	case plans.NoOp:
+		// This should never be possible: a no-op planned change should not
+		// be applied. We'll fall back to "Applying".
+		fallthrough
 	default:
 		return "Applying"
 	}
@@ -336,6 +340,10 @@ func progressActionVerb(action plans.Action) string {
 		// This is not currently possible to reach, as we receive separate
 		// passes for create and delete
 		return "replacing"
+	case plans.NoOp:
+		// This should never be possible: a no-op planned change should not
+		// be applied. We'll fall back to "applying".
+		fallthrough
 	default:
 		return "applying"
 	}
@@ -358,6 +366,10 @@ func actionNoun(action plans.Action) string {
 		// This is not currently possible to reach, as we receive separate
 		// passes for create and delete
 		return "Replacement"
+	case plans.NoOp:
+		// This should never be possible: a no-op planned change should not
+		// be applied. We'll fall back to "Apply".
+		fallthrough
 	default:
 		return "Apply"
 	}

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

@@ -126,10 +126,15 @@ At the end of a plan or before an apply, Terraform will emit a `planned_change`
 - `resource`: object describing the address of the resource to be changed; see [resource object](#resource-object) below for details
 - `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:
+- `reason`: an optional reason for the change, currently only used when the action is `replace` or `delete`. Values:
     - `tainted`: resource was marked as tainted
     - `requested`: user requested that the resource be replaced, for example via the `-replace` plan flag
     - `cannot_update`: changes to configuration force the resource to be deleted and created rather than updated
+    - `delete_because_no_resource_config`: no matching resource in configuration
+    - `delete_because_wrong_repetition`: resource instance key has no corresponding `count` or `for_each` in configuration
+    - `delete_because_count_index`: resource instance key is outside the range of the `count` argument
+    - `delete_because_each_key`: resource instance key is not included in the `for_each` argument
+    - `delete_because_no_module`: enclosing module instance is not in configuration
 
 This message does not include details about the exact changes which caused the change to be planned. That information is available in [the JSON plan output](./json-format.html).