fix: resolve critical Aurora CDK issues

- Add validation for required vpcId and subnetIds props
- Set default username to 'clusteradmin' when not provided
- Update to latest Aurora engine versions (PostgreSQL 15.4, MySQL 3.04.0)
- Fix typo in secret description (Crendetials -> Credentials)
- Use validated instanceType variable in cluster creation
- Add app.synth() call to generate CloudFormation templates
- Update example with realistic placeholder values

Author: Sunil Yadav

typescript/rds/aurora/aurora.ts

@@ -137,12 +137,18 @@ export class Aurora extends Stack {
 //export class Aurora extends Construct {
   constructor(scope: Construct, id: string, props:AuroraProps) {
   //constructor(scope: Construct, id: string, props?: cdk.StackProps) {
-    super(scope, id);
+    super(scope, id, props);
+
+    // Validate required props
+    if (!props.vpcId || !props.subnetIds?.length) {
+      throw new Error('vpcId and subnetIds are required');
+    }
 
     let subnetIds = props.subnetIds;
     let instanceType = props.instanceType;
     let replicaInstances = props.replicaInstances ?? 1;
     let backupRetentionDays = props.backupRetentionDays ?? 14;
+    let auroraClusterUsername = props.auroraClusterUsername ?? 'clusteradmin';
 
     let ingressSources = [];
     if (typeof props.ingressSources !== 'undefined') {
@@ -223,12 +229,12 @@ export class Aurora extends Stack {
 
     // Declaring postgres engine
     let auroraEngine = rds.DatabaseClusterEngine.auroraPostgres({
-      version: rds.AuroraPostgresEngineVersion.VER_13_4,
+      version: rds.AuroraPostgresEngineVersion.VER_15_4,
     });
 
     if (props.engine == 'mysql') {
       auroraEngine = rds.DatabaseClusterEngine.auroraMysql({
-        version: rds.AuroraMysqlEngineVersion.VER_2_10_1,
+        version: rds.AuroraMysqlEngineVersion.VER_3_04_0,
       });
     }
 
@@ -254,20 +260,20 @@ export class Aurora extends Stack {
       'AuroraClusterCredentials',
       {
         secretName: props.dbName + 'AuroraClusterCredentials',
-        description: props.dbName + 'AuroraClusterCrendetials',
+        description: props.dbName + 'AuroraClusterCredentials',
         generateSecretString: {
           excludeCharacters: "\"@/\\ '",
           generateStringKey: 'password',
           passwordLength: 30,
-          secretStringTemplate: JSON.stringify({username: props.auroraClusterUsername}),
+          secretStringTemplate: JSON.stringify({username: auroraClusterUsername}),
         },
       },
     );
 
     // aurora credentials
     const auroraClusterCrendentials= rds.Credentials.fromSecret(
       auroraClusterSecret,
-      props.auroraClusterUsername,
+      auroraClusterUsername,
     );
 
     if (instanceType == null || instanceType == undefined) {
@@ -308,7 +314,7 @@ export class Aurora extends Stack {
       preferredMaintenanceWindow: props.preferredMaintenanceWindow,
       instanceIdentifierBase: props.dbName,
       instanceProps: {
-        instanceType: props.instanceType,
+        instanceType: instanceType,
         vpcSubnets: vpcSubnets,
         vpc: vpc,
         securityGroups: [dbsg],
@@ -521,5 +527,7 @@ new Aurora(app, 'AuroraStack', {
   engine:"postgresql"
 });
 
+app.synth();
+