From 06b319ddd752e4f3f73752fdda5f7151d640ff5f Mon Sep 17 00:00:00 2001
From: akash1810 <akash1810@users.noreply.github.com>
Date: Thu, 26 Sep 2024 08:18:43 +0100
Subject: [PATCH] feat(cloud-formation): Preserve existing tags

Update the `cloud-formation` deployment type to preserve any existing tags on the CloudFormation stack.
---
 .../main/scala/magenta/tasks/ChangeSetTasks.scala | 15 ++++++++++-----
 .../scala/magenta/tasks/SetStackPolicyTask.scala  |  2 +-
 .../magenta/tasks/UpdateCloudFormationTask.scala  |  9 +++++++--
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/magenta-lib/src/main/scala/magenta/tasks/ChangeSetTasks.scala b/magenta-lib/src/main/scala/magenta/tasks/ChangeSetTasks.scala
index 9193f9abc..9dd6b9479 100644
--- a/magenta-lib/src/main/scala/magenta/tasks/ChangeSetTasks.scala
+++ b/magenta-lib/src/main/scala/magenta/tasks/ChangeSetTasks.scala
@@ -42,7 +42,7 @@ class CreateChangeSetTask(
                 )
               )
 
-            val (stackName, changeSetType, existingParameters) =
+            val (stackName, changeSetType, existingParameters, currentTags) =
               stackLookup.lookup(resources.reporter, cfnClient)
 
             val template = processTemplate(
@@ -106,12 +106,15 @@ class CreateChangeSetTask(
               resources.reporter.verbose(s"Using execution role $role")
             )
 
+            val mergedTags = currentTags ++ stackTags
+            resources.reporter.info("Tags: " + mergedTags.mkString(", "))
+
             CloudFormation.createChangeSet(
               resources.reporter,
               stackLookup.changeSetName,
               changeSetType,
               stackName,
-              Some(stackTags),
+              Some(mergedTags),
               template,
               awsParameters,
               maybeExecutionRole,
@@ -162,7 +165,7 @@ class CheckChangeSetCreatedTask(
   ): Unit = {
     check(resources.reporter, stopFlag) {
       CloudFormation.withCfnClient(keyRing, region, resources) { cfnClient =>
-        val (stackName, changeSetType, _) =
+        val (stackName, changeSetType, _, _) =
           stackLookup.lookup(resources.reporter, cfnClient)
         val changeSetName = stackLookup.changeSetName
         val changeSet = CloudFormation.describeChangeSetByName(
@@ -240,7 +243,8 @@ class ExecuteChangeSetTask(
       stopFlag: => Boolean
   ): Unit = {
     CloudFormation.withCfnClient(keyRing, region, resources) { cfnClient =>
-      val (stackName, _, _) = stackLookup.lookup(resources.reporter, cfnClient)
+      val (stackName, _, _, _) =
+        stackLookup.lookup(resources.reporter, cfnClient)
       val changeSetName = stackLookup.changeSetName
 
       val changeSet = CloudFormation.describeChangeSetByName(
@@ -306,7 +310,8 @@ class DeleteChangeSetTask(
       stopFlag: => Boolean
   ): Unit = {
     CloudFormation.withCfnClient(keyRing, region, resources) { cfnClient =>
-      val (stackName, _, _) = stackLookup.lookup(resources.reporter, cfnClient)
+      val (stackName, _, _, _) =
+        stackLookup.lookup(resources.reporter, cfnClient)
       val changeSetName = stackLookup.changeSetName
 
       CloudFormation.deleteChangeSet(stackName, changeSetName, cfnClient)
diff --git a/magenta-lib/src/main/scala/magenta/tasks/SetStackPolicyTask.scala b/magenta-lib/src/main/scala/magenta/tasks/SetStackPolicyTask.scala
index f1a3c8411..0a3bec6d5 100644
--- a/magenta-lib/src/main/scala/magenta/tasks/SetStackPolicyTask.scala
+++ b/magenta-lib/src/main/scala/magenta/tasks/SetStackPolicyTask.scala
@@ -211,7 +211,7 @@ class SetStackPolicyTask(
       stopFlag: => Boolean
   ): Unit = {
     CloudFormation.withCfnClient(keyRing, region, resources) { cfnClient =>
-      val (stackName, changeSetType, _) =
+      val (stackName, changeSetType, _, _) =
         stackLookup.lookup(resources.reporter, cfnClient)
       val policyDoc =
         toPolicyDoc(stackPolicy, () => accountResourceTypes(cfnClient))
diff --git a/magenta-lib/src/main/scala/magenta/tasks/UpdateCloudFormationTask.scala b/magenta-lib/src/main/scala/magenta/tasks/UpdateCloudFormationTask.scala
index 136b6b6ed..559a14ba2 100644
--- a/magenta-lib/src/main/scala/magenta/tasks/UpdateCloudFormationTask.scala
+++ b/magenta-lib/src/main/scala/magenta/tasks/UpdateCloudFormationTask.scala
@@ -98,7 +98,7 @@ class CloudFormationStackMetadata(
   def lookup(
       reporter: DeployReporter,
       cfnClient: CloudFormationClient
-  ): (String, ChangeSetType, List[ExistingParameter]) = {
+  ): (String, ChangeSetType, List[ExistingParameter], Map[String, String]) = {
     val existingStack = strategy match {
       case LookupByName(name) => CloudFormation.describeStack(name, cfnClient)
       case LookupByTags(tags) =>
@@ -123,7 +123,12 @@ class CloudFormationStackMetadata(
       reporter
     )
 
-    (stackName, changeSetType, stackParameters)
+    val currentTags: Map[String, String] = existingStack match {
+      case Some(stack) => stack.tags().asScala.map(t => t.key -> t.value).toMap
+      case _           => Map.empty
+    }
+
+    (stackName, changeSetType, stackParameters, currentTags)
   }
 }