replace DynamoDB Streams for the notifications-lambda with SQS and …

…a AppSync pipeline resolver Co-Authored-By: Andrew Nowak <andrew.nowak@guardian.co.uk>
guardian · Aug 10, 2022 · c2fc114 · c2fc114
1 parent ce8309a
commit c2fc114
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Showing 7 changed files with 365 additions and 110 deletions.
diff --git a/cdk/package.json b/cdk/package.json
@@ -28,6 +28,7 @@
     "@aws-cdk/aws-lambda-event-sources": "1.147.0",
     "@aws-cdk/aws-s3": "1.147.0",
     "@aws-cdk/aws-ssm": "1.147.0",
+    "@aws-cdk/aws-sqs": "1.147.0",
     "@aws-cdk/core": "1.147.0"
   }
 }
diff --git a/cdk/stack.ts b/cdk/stack.ts
@@ -13,6 +13,7 @@ import * as lambda from "@aws-cdk/aws-lambda";
 import * as S3 from "@aws-cdk/aws-s3";
 import * as iam from "@aws-cdk/aws-iam";
 import * as ssm from "@aws-cdk/aws-ssm";
+import * as sqs from "@aws-cdk/aws-sqs";
 import * as apigateway from "@aws-cdk/aws-apigateway";
 import * as appsync from "@aws-cdk/aws-appsync";
 import * as db from "@aws-cdk/aws-dynamodb";
@@ -23,7 +24,7 @@ import * as eventsTargets from "@aws-cdk/aws-events-targets";
 import { join } from "path";
 import { APP } from "../shared/constants";
 import crypto from "crypto";
-import { DynamoEventSource } from "@aws-cdk/aws-lambda-event-sources";
+import { SqsEventSource } from "@aws-cdk/aws-lambda-event-sources";
 import { ENVIRONMENT_VARIABLE_KEYS } from "../shared/environmentVariables";
 
 export class PinBoardStack extends Stack {
@@ -183,6 +184,11 @@ export class PinBoardStack extends Stack {
 
     const pinboardNotificationsLambdaBasename = "pinboard-notifications-lambda";
 
+    const pinboardNotificationsSQS = new sqs.Queue(
+      thisStack,
+      `${pinboardNotificationsLambdaBasename}-sqs`
+    );
+
     const pinboardNotificationsLambda = new lambda.Function(
       thisStack,
       pinboardNotificationsLambdaBasename,
@@ -197,16 +203,30 @@ export class PinBoardStack extends Stack {
           APP,
           [ENVIRONMENT_VARIABLE_KEYS.usersTableName]:
             pinboardAppsyncUserTable.tableName,
+          [ENVIRONMENT_VARIABLE_KEYS.notificationQueueURL]:
+            pinboardNotificationsSQS.queueUrl,
         },
         functionName: `${pinboardNotificationsLambdaBasename}-${STAGE}`,
         code: lambda.Code.fromBucket(
           deployBucket,
           `${STACK}/${STAGE}/${pinboardNotificationsLambdaBasename}/${pinboardNotificationsLambdaBasename}.zip`
         ),
-        initialPolicy: [readPinboardParamStorePolicyStatement],
+        initialPolicy: [
+          readPinboardParamStorePolicyStatement,
+          new iam.PolicyStatement({
+            actions: ["sqs:SendMessage"],
+            effect: iam.Effect.ALLOW,
+            resources: [pinboardNotificationsSQS.queueArn],
+          }),
+        ],
       }
     );
     pinboardAppsyncUserTable.grantReadData(pinboardNotificationsLambda);
+    pinboardNotificationsLambda.addEventSource(
+      new SqsEventSource(pinboardNotificationsSQS, {
+        reportBatchItemFailures: true,
+      })
+    );
 
     const pinboardAuthLambdaBasename = "pinboard-auth-lambda";
 
@@ -286,13 +306,6 @@ export class PinBoardStack extends Stack {
       }
     );
 
-    pinboardNotificationsLambda.addEventSource(
-      new DynamoEventSource(pinboardAppsyncItemTable, {
-        maxBatchingWindow: Duration.seconds(10),
-        startingPosition: lambda.StartingPosition.LATEST,
-      })
-    );
-
     const pinboardLastItemSeenByUserTableBaseName =
       "pinboard-last-item-seen-by-user-table";
 
@@ -329,6 +342,14 @@ export class PinBoardStack extends Stack {
       pinboardGridBridgeLambda
     );
 
+    const pinboardNotificationsLambdaDataSource = pinboardAppsyncApi.addLambdaDataSource(
+      `${pinboardNotificationsLambdaBasename
+        .replace("pinboard-", "")
+        .split("-")
+        .join("_")}_ds`,
+      pinboardNotificationsLambda
+    );
+
     const pinboardItemDataSource = pinboardAppsyncApi.addDynamoDbDataSource(
       `${pinboardItemTableBaseName
         .replace("pinboard-", "")
@@ -374,38 +395,73 @@ export class PinBoardStack extends Stack {
         }
       `)
     );
-    const dynamoFilterResponseMappingTemplate = appsync.MappingTemplate.fromString(
+    const basicResponseMappingTemplate = appsync.MappingTemplate.fromString(
       "$util.toJson($context.result)"
     );
 
     pinboardItemDataSource.createResolver({
       typeName: "Query",
       fieldName: "listItems",
       requestMappingTemplate: dynamoFilterRequestMappingTemplate,
-      responseMappingTemplate: dynamoFilterResponseMappingTemplate,
+      responseMappingTemplate: basicResponseMappingTemplate,
     });
 
-    pinboardItemDataSource.createResolver({
+    const insertItemPipelineFunction = new appsync.AppsyncFunction(
+      thisStack,
+      "pinboard-insert-item-pipeline-function",
+      {
+        name: "insert_item",
+        api: pinboardAppsyncApi,
+        dataSource: pinboardItemDataSource,
+        requestMappingTemplate: resolverBugWorkaround(
+          appsync.MappingTemplate.dynamoDbPutItem(
+            appsync.PrimaryKey.partition("id").auto(),
+            appsync.Values.projecting("input")
+              .attribute("timestamp")
+              .is("$util.time.nowEpochSeconds()")
+              .attribute("userEmail")
+              .is("$ctx.identity.resolverContext.userEmail")
+          )
+        ),
+        responseMappingTemplate: appsync.MappingTemplate.dynamoDbResultItem(),
+      }
+    );
+
+    const queueNotificationPipelineFunction = new appsync.AppsyncFunction(
+      thisStack,
+      "pinboard-queue-notification-pipeline-function",
+      {
+        name: "queue_notification",
+        api: pinboardAppsyncApi,
+        dataSource: pinboardNotificationsLambdaDataSource,
+        requestMappingTemplate: resolverBugWorkaround(
+          appsync.MappingTemplate.lambdaRequest(
+            "$util.toJson($ctx.prev.result)",
+            "Invoke"
+          )
+        ),
+        responseMappingTemplate: appsync.MappingTemplate.lambdaResult(),
+      }
+    );
+
+    pinboardAppsyncApi.createResolver({
       typeName: "Mutation",
       fieldName: "createItem",
       requestMappingTemplate: resolverBugWorkaround(
-        appsync.MappingTemplate.dynamoDbPutItem(
-          appsync.PrimaryKey.partition("id").auto(),
-          appsync.Values.projecting("input")
-            .attribute("timestamp")
-            .is("$util.time.nowEpochSeconds()")
-            .attribute("userEmail")
-            .is("$ctx.identity.resolverContext.userEmail")
-        )
+        appsync.MappingTemplate.fromString("{}")
       ),
-      responseMappingTemplate: appsync.MappingTemplate.dynamoDbResultItem(),
+      pipelineConfig: [
+        insertItemPipelineFunction,
+        queueNotificationPipelineFunction,
+      ],
+      responseMappingTemplate: basicResponseMappingTemplate,
     });
 
     pinboardLastItemSeenByUserDataSource.createResolver({
       typeName: "Query",
       fieldName: "listLastItemSeenByUsers",
       requestMappingTemplate: dynamoFilterRequestMappingTemplate, // TODO consider custom resolver for performance
-      responseMappingTemplate: dynamoFilterResponseMappingTemplate,
+      responseMappingTemplate: basicResponseMappingTemplate,
     });
 
     pinboardLastItemSeenByUserDataSource.createResolver({
@@ -479,7 +535,7 @@ export class PinBoardStack extends Stack {
         }
       `)
       ),
-      responseMappingTemplate: dynamoFilterResponseMappingTemplate,
+      responseMappingTemplate: basicResponseMappingTemplate,
     });
 
     pinboardUserDataSource.createResolver({