fix(dynamodb): replicas not created on table replacement (aws#13300)

Process `Update` events resulting from table replacements. Include the table name in the physical resource id to receive a `Delete` event when the table is replaced. This allows to clean "old" replicas. Use a managed policy instead of an inline policy for the custom resource. An update of the description property of a managed policy requires a replacement. If we use the table name in the description it forces a managed policy replacement when the table name changes. This way we preserve permissions to delete old replicas in case of a table replacement: a new managed policy with permissions for the new table is created during the update phase and the old managed policy with permissions for the old table is removed only during the update clean up phase. The logical ID of the `SourceTableAttachedPolicy` needs to be updated because CF doesn't allow to change a resource type. Closes aws#12332 ---- *By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*
cornerwings · Mar 8, 2021 · 41d15e9 · 41d15e9
1 parent 0979ea4
commit 41d15e9
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diff --git a/packages/@aws-cdk/aws-dynamodb/lib/replica-handler/index.ts b/packages/@aws-cdk/aws-dynamodb/lib/replica-handler/index.ts
@@ -5,27 +5,34 @@ import { DynamoDB } from 'aws-sdk'; // eslint-disable-line import/no-extraneous-
 export async function onEventHandler(event: OnEventRequest): Promise<OnEventResponse> {
   console.log('Event: %j', event);
 
-  /**
-   * Process only Create and Delete requests. We shouldn't receive any
-   * update request and in case we do there is nothing to update.
-   */
+  const dynamodb = new DynamoDB();
+
+  let updateTableAction: 'Create' | 'Update' | 'Delete';
   if (event.RequestType === 'Create' || event.RequestType === 'Delete') {
-    const dynamodb = new DynamoDB();
-
-    const data = await dynamodb.updateTable({
-      TableName: event.ResourceProperties.TableName,
-      ReplicaUpdates: [
-        {
-          [event.RequestType]: {
-            RegionName: event.ResourceProperties.Region,
-          },
-        },
-      ],
-    }).promise();
-    console.log('Update table: %j', data);
+    updateTableAction = event.RequestType;
+  } else { // Update
+    // This can only be a table replacement so we create a replica
+    // in the new table. The replica for the "old" table will be
+    // deleted when CF issues a Delete event on the old physical
+    // resource id.
+    updateTableAction = 'Create';
   }
 
-  return { PhysicalResourceId: event.ResourceProperties.Region };
+  const data = await dynamodb.updateTable({
+    TableName: event.ResourceProperties.TableName,
+    ReplicaUpdates: [
+      {
+        [updateTableAction]: {
+          RegionName: event.ResourceProperties.Region,
+        },
+      },
+    ],
+  }).promise();
+  console.log('Update table: %j', data);
+
+  return event.RequestType === 'Create' || event.RequestType === 'Update'
+    ? { PhysicalResourceId: `${event.ResourceProperties.TableName}-${event.ResourceProperties.Region}` }
+    : {};
 }
 
 export async function isCompleteHandler(event: IsCompleteRequest): Promise<IsCompleteResponse> {

diff --git a/packages/@aws-cdk/aws-dynamodb/lib/table.ts b/packages/@aws-cdk/aws-dynamodb/lib/table.ts
@@ -1670,12 +1670,19 @@ interface ScalableAttributePair {
  */
 class SourceTableAttachedPolicy extends CoreConstruct implements iam.IGrantable {
   public readonly grantPrincipal: iam.IPrincipal;
-  public readonly policy: iam.IPolicy;
+  public readonly policy: iam.IManagedPolicy;
 
   public constructor(sourceTable: Table, role: iam.IRole) {
-    super(sourceTable, `SourceTableAttachedPolicy-${Names.nodeUniqueId(role.node)}`);
-
-    const policy = new iam.Policy(this, 'Resource', { roles: [role] });
+    super(sourceTable, `SourceTableAttachedManagedPolicy-${Names.nodeUniqueId(role.node)}`);
+
+    const policy = new iam.ManagedPolicy(this, 'Resource', {
+      // A CF update of the description property of a managed policy requires
+      // a replacement. Use the table name in the description to force a managed
+      // policy replacement when the table name changes. This way we preserve permissions
+      // to delete old replicas in case of a table replacement.
+      description: `DynamoDB replication managed policy for table ${sourceTable.tableName}`,
+      roles: [role],
+    });
     this.policy = policy;
     this.grantPrincipal = new SourceTableAttachedPrincipal(role, policy);
   }
@@ -1686,7 +1693,7 @@ class SourceTableAttachedPolicy extends CoreConstruct implements iam.IGrantable
  * `SourceTableAttachedPolicy` class so it can act as an `IGrantable`.
  */
 class SourceTableAttachedPrincipal extends iam.PrincipalBase {
-  public constructor(private readonly role: iam.IRole, private readonly policy: iam.Policy) {
+  public constructor(private readonly role: iam.IRole, private readonly policy: iam.ManagedPolicy) {
     super();
   }
 

diff --git a/packages/@aws-cdk/aws-dynamodb/test/integ.global-replicas-provisioned.expected.json b/packages/@aws-cdk/aws-dynamodb/test/integ.global-replicas-provisioned.expected.json
@@ -26,8 +26,8 @@
       "UpdateReplacePolicy": "Delete",
       "DeletionPolicy": "Delete"
     },
-    "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B77945CD5DF": {
-      "Type": "AWS::IAM::Policy",
+    "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B771F8F2CCB": {
+      "Type": "AWS::IAM::ManagedPolicy",
       "Properties": {
         "PolicyDocument": {
           "Statement": [
@@ -93,7 +93,18 @@
           ],
           "Version": "2012-10-17"
         },
-        "PolicyName": "leAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B77945CD5DF",
+        "Description": {
+          "Fn::Join": [
+            "",
+            [
+              "DynamoDB replication managed policy for table ",
+              {
+                "Ref": "TableCD117FA1"
+              }
+            ]
+          ]
+        },
+        "Path": "/",
         "Roles": [
           {
             "Fn::GetAtt": [
@@ -104,8 +115,8 @@
         ]
       }
     },
-    "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1AE3D3CF6D": {
-      "Type": "AWS::IAM::Policy",
+    "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1A5DC546D2": {
+      "Type": "AWS::IAM::ManagedPolicy",
       "Properties": {
         "PolicyDocument": {
           "Statement": [
@@ -127,7 +138,18 @@
           ],
           "Version": "2012-10-17"
         },
-        "PolicyName": "ttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1AE3D3CF6D",
+        "Description": {
+          "Fn::Join": [
+            "",
+            [
+              "DynamoDB replication managed policy for table ",
+              {
+                "Ref": "TableCD117FA1"
+              }
+            ]
+          ]
+        },
+        "Path": "/",
         "Roles": [
           {
             "Fn::GetAtt": [
@@ -153,8 +175,8 @@
         "Region": "us-east-2"
       },
       "DependsOn": [
-        "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1AE3D3CF6D",
-        "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B77945CD5DF",
+        "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1A5DC546D2",
+        "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B771F8F2CCB",
         "TableWriteScalingTargetE5669214",
         "TableWriteScalingTargetTrackingD78DCCD8"
       ],
@@ -178,8 +200,8 @@
       },
       "DependsOn": [
         "TableReplicauseast28A15C236",
-        "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1AE3D3CF6D",
-        "TableSourceTableAttachedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B77945CD5DF",
+        "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderIsCompleteHandlerServiceRoleBE2B1C1A5DC546D2",
+        "TableSourceTableAttachedManagedPolicyawscdkdynamodbglobalreplicasprovisionedawscdkawsdynamodbReplicaProviderOnEventHandlerServiceRoleD9856B771F8F2CCB",
         "TableWriteScalingTargetE5669214",
         "TableWriteScalingTargetTrackingD78DCCD8"
       ],
@@ -256,7 +278,7 @@
               },
               "/",
               {
-                "Ref": "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdS3BucketEDAACFE7"
+                "Ref": "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadS3Bucket806FEB2C"
               },
               "/",
               {
@@ -266,7 +288,7 @@
                     "Fn::Split": [
                       "||",
                       {
-                        "Ref": "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdS3VersionKey6FF3D50F"
+                        "Ref": "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadS3VersionKey81C7BC5B"
                       }
                     ]
                   }
@@ -279,7 +301,7 @@
                     "Fn::Split": [
                       "||",
                       {
-                        "Ref": "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdS3VersionKey6FF3D50F"
+                        "Ref": "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadS3VersionKey81C7BC5B"
                       }
                     ]
                   }
@@ -289,11 +311,11 @@
           ]
         },
         "Parameters": {
-          "referencetoawscdkdynamodbglobalreplicasprovisionedAssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3Bucket50997EC4Ref": {
-            "Ref": "AssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3Bucket1C6779E0"
+          "referencetoawscdkdynamodbglobalreplicasprovisionedAssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3BucketD1258B42Ref": {
+            "Ref": "AssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3BucketDEBF01E6"
           },
-          "referencetoawscdkdynamodbglobalreplicasprovisionedAssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3VersionKey0F47C425Ref": {
-            "Ref": "AssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3VersionKey5C1D9275"
+          "referencetoawscdkdynamodbglobalreplicasprovisionedAssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3VersionKey0F5C355ERef": {
+            "Ref": "AssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3VersionKey42EBA2AE"
           },
           "referencetoawscdkdynamodbglobalreplicasprovisionedAssetParametersdaeb79e3cee39c9b902dc0d5c780223e227ed573ea60976252947adab5fb2be1S3Bucket6C51C355Ref": {
             "Ref": "AssetParametersdaeb79e3cee39c9b902dc0d5c780223e227ed573ea60976252947adab5fb2be1S3BucketDC4B98B1"
@@ -334,17 +356,17 @@
     }
   },
   "Parameters": {
-    "AssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3Bucket1C6779E0": {
+    "AssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3BucketDEBF01E6": {
       "Type": "String",
-      "Description": "S3 bucket for asset \"f13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714\""
+      "Description": "S3 bucket for asset \"dd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776\""
     },
-    "AssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714S3VersionKey5C1D9275": {
+    "AssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776S3VersionKey42EBA2AE": {
       "Type": "String",
-      "Description": "S3 key for asset version \"f13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714\""
+      "Description": "S3 key for asset version \"dd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776\""
     },
-    "AssetParametersf13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714ArtifactHash477AAEA7": {
+    "AssetParametersdd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776ArtifactHash692B4CCE": {
       "Type": "String",
-      "Description": "Artifact hash for asset \"f13d472270faaa08099009152a8848a0e7434b14773f3c3f94acca6f6c3ae714\""
+      "Description": "Artifact hash for asset \"dd0a4ac30ffa331e472caec08a7784ac440d122a6f924b1bea7d48dc85f8f776\""
     },
     "AssetParametersdaeb79e3cee39c9b902dc0d5c780223e227ed573ea60976252947adab5fb2be1S3BucketDC4B98B1": {
       "Type": "String",
@@ -358,17 +380,17 @@
       "Type": "String",
       "Description": "Artifact hash for asset \"daeb79e3cee39c9b902dc0d5c780223e227ed573ea60976252947adab5fb2be1\""
     },
-    "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdS3BucketEDAACFE7": {
+    "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadS3Bucket806FEB2C": {
       "Type": "String",
-      "Description": "S3 bucket for asset \"e31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fd\""
+      "Description": "S3 bucket for asset \"d56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aad\""
     },
-    "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdS3VersionKey6FF3D50F": {
+    "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadS3VersionKey81C7BC5B": {
       "Type": "String",
-      "Description": "S3 key for asset version \"e31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fd\""
+      "Description": "S3 key for asset version \"d56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aad\""
     },
-    "AssetParameterse31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fdArtifactHash898696F1": {
+    "AssetParametersd56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aadArtifactHashD0230F6F": {
       "Type": "String",
-      "Description": "Artifact hash for asset \"e31d108faccc52dcd9a9d86276a05e6ad861311925fe6931eadc31d0fe17e1fd\""
+      "Description": "Artifact hash for asset \"d56d097acd2563516c51a0e04dcf8d9bf3638678f723d5b80f95d5c240836aad\""
     }
   }
 }