From 158743194580ac8d5b1b2cfa9cac52a9c1394357 Mon Sep 17 00:00:00 2001
From: "Alexander A. Klimov" <alexander.klimov@icinga.com>
Date: Tue, 13 Jun 2023 16:40:33 +0200
Subject: [PATCH] POST /v1/objects: allow array of attrs to undo modifications
 of

---
 doc/12-icinga2-api.md              | 42 ++++++++++++++++++++++++--
 lib/remote/modifyobjecthandler.cpp | 48 +++++++++++++++++++++++++++---
 2 files changed, 83 insertions(+), 7 deletions(-)

diff --git a/doc/12-icinga2-api.md b/doc/12-icinga2-api.md
index 6b23c607c98..85c9aad867b 100644
--- a/doc/12-icinga2-api.md
+++ b/doc/12-icinga2-api.md
@@ -890,9 +890,17 @@ curl -k -s -S -i -u root:icinga -H 'Accept: application/json' \
 Existing objects must be modified by sending a `POST` request. The following
 parameters need to be passed inside the JSON body:
 
-  Parameters | Type       | Description
-  -----------|------------|---------------------------
-  attrs      | Dictionary | **Required.** Set specific object attributes for this [object type](09-object-types.md#object-types).
+| Parameters     | Type       | Description                                                                                                                |
+|----------------|------------|----------------------------------------------------------------------------------------------------------------------------|
+| attrs          | Dictionary | **Optional.** Set specific object attributes for this [object type](09-object-types.md#object-types).                      |
+| restore\_attrs | Array      | **Optional.** Discard modifications of specific object attributes for this [object type](09-object-types.md#object-types). |
+
+One of the above is required.
+
+!!! info
+
+    If a particular attribute is given in both sets,
+    it's first restored and then set to the desired new value.
 
 In addition to these parameters a [filter](12-icinga2-api.md#icinga2-api-filters)
 parameter should be provided.
@@ -936,6 +944,34 @@ curl -k -s -S -i -u root:icinga -H 'Accept: application/json' \
 }
 ```
 
+To undo such modifications to specific object attributes,
+list the latter in the `restore_attrs` parameter. E.g.:
+
+```bash
+curl -k -s -S -i -u root:icinga -H 'Accept: application/json' \
+ -X POST 'https://localhost:5665/v1/objects/hosts/example.localdomain' \
+ -d '{ "restore_attrs": [ "address", "vars.os" ] }, "pretty": true }'
+```
+
+```json
+{
+    "results": [
+        {
+            "code": 200.0,
+            "name": "example.localdomain",
+            "status": "Attributes updated.",
+            "type": "Host"
+        }
+    ]
+}
+```
+
+Giving `attrs` with the original value would have almost the same effect.
+But in this case Icinga would still store that value as a modified attribute,
+overriding DSL/Director config (changes). In contrast, `restore_attrs` tells
+Icinga to actually forget particular modified attributes, so that changes to
+them via Director or plain config are effective again.
+
 ### Deleting Objects <a id="icinga2-api-config-objects-delete"></a>
 
 You can delete objects created using the API by sending a `DELETE`
diff --git a/lib/remote/modifyobjecthandler.cpp b/lib/remote/modifyobjecthandler.cpp
index d9a215f5ff5..d6fa98b2e32 100644
--- a/lib/remote/modifyobjecthandler.cpp
+++ b/lib/remote/modifyobjecthandler.cpp
@@ -64,7 +64,7 @@ bool ModifyObjectHandler::HandleRequest(
 
 	Value attrsVal = params->Get("attrs");
 
-	if (attrsVal.GetReflectionType() != Dictionary::TypeInstance) {
+	if (attrsVal.GetReflectionType() != Dictionary::TypeInstance && attrsVal.GetType() != ValueEmpty) {
 		HttpUtility::SendJsonError(response, params, 400,
 			"Invalid type for 'attrs' attribute specified. Dictionary type is required."
 			"Or is this a POST query and you missed adding a 'X-HTTP-Method-Override: GET' header?");
@@ -73,6 +73,23 @@ bool ModifyObjectHandler::HandleRequest(
 
 	Dictionary::Ptr attrs = attrsVal;
 
+	Value restoreAttrsVal = params->Get("restore_attrs");
+
+	if (restoreAttrsVal.GetReflectionType() != Array::TypeInstance && restoreAttrsVal.GetType() != ValueEmpty) {
+		HttpUtility::SendJsonError(response, params, 400,
+			"Invalid type for 'restore_attrs' attribute specified. Array type is required.");
+		return true;
+	}
+
+	Array::Ptr restoreAttrs = restoreAttrsVal;
+
+	if (!(attrs || restoreAttrs)) {
+		HttpUtility::SendJsonError(response, params, 400,
+			"Missing both 'attrs' and 'restore_attrs'. "
+			"Or is this a POST query and you missed adding a 'X-HTTP-Method-Override: GET' header?");
+		return true;
+	}
+
 	bool verbose = false;
 
 	if (params)
@@ -95,6 +112,26 @@ bool ModifyObjectHandler::HandleRequest(
 
 		String key;
 
+		try {
+			if (restoreAttrs) {
+				ObjectLock oLock (restoreAttrs);
+
+				for (auto& attr : restoreAttrs) {
+					key = attr;
+					obj->RestoreAttribute(key);
+				}
+			}
+		} catch (const std::exception& ex) {
+			result1->Set("code", 500);
+			result1->Set("status", "Attribute '" + key + "' could not be restored: " + DiagnosticInformation(ex, false));
+
+			if (verbose)
+				result1->Set("diagnostic_information", DiagnosticInformation(ex));
+
+			results.push_back(std::move(result1));
+			continue;
+		}
+
 		try {
 			if (attrs) {
 				ObjectLock olock(attrs);
@@ -103,17 +140,20 @@ bool ModifyObjectHandler::HandleRequest(
 					obj->ModifyAttribute(kv.first, kv.second);
 				}
 			}
-
-			result1->Set("code", 200);
-			result1->Set("status", "Attributes updated.");
 		} catch (const std::exception& ex) {
 			result1->Set("code", 500);
 			result1->Set("status", "Attribute '" + key + "' could not be set: " + DiagnosticInformation(ex, false));
 
 			if (verbose)
 				result1->Set("diagnostic_information", DiagnosticInformation(ex));
+
+			results.push_back(std::move(result1));
+			continue;
 		}
 
+		result1->Set("code", 200);
+		result1->Set("status", "Attributes updated.");
+
 		results.push_back(std::move(result1));
 	}