From 87d50e770dea9f0562303f4422ae5785aefc92d0 Mon Sep 17 00:00:00 2001
From: mokocm <mokocmmoko@gmail.com>
Date: Fri, 19 Aug 2022 17:12:25 +0900
Subject: [PATCH 1/2] Added logGroups Properties

---
 packages/@aws-cdk/aws-rds/lib/instance.ts     | 22 ++++++++++++++-----
 .../@aws-cdk/aws-rds/test/instance.test.ts    | 20 +++++++++++++++++
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/packages/@aws-cdk/aws-rds/lib/instance.ts b/packages/@aws-cdk/aws-rds/lib/instance.ts
index 9b94564122ff2..2133f95abb42a 100644
--- a/packages/@aws-cdk/aws-rds/lib/instance.ts
+++ b/packages/@aws-cdk/aws-rds/lib/instance.ts
@@ -644,6 +644,11 @@ abstract class DatabaseInstanceNew extends DatabaseInstanceBase implements IData
 
   protected enableIamAuthentication?: boolean;
 
+  /**
+   * List of LogGroups when CloudWatch log output is enabled.
+   */
+  public abstract readonly logGroups: logs.ILogGroup[];
+
   constructor(scope: Construct, id: string, props: DatabaseInstanceNewProps) {
     // RDS always lower-cases the ID of the database, so use that for the physical name
     // (which is the name used for cross-environment access, so it needs to be correct,
@@ -762,16 +767,20 @@ abstract class DatabaseInstanceNew extends DatabaseInstanceBase implements IData
     };
   }
 
-  protected setLogRetention() {
+  protected setLogRetention(): logs.ILogGroup[] {
+    const logGroups: logs.ILogGroup[] = [];
     if (this.cloudwatchLogsExports && this.cloudwatchLogsRetention) {
       for (const log of this.cloudwatchLogsExports) {
+        const logGroupName = `/aws/rds/instance/${this.instanceIdentifier}/${log}`;
+        logGroups.push(logs.LogGroup.fromLogGroupName(this, `LogGroup${this.instanceIdentifier}${log}`, logGroupName));
         new logs.LogRetention(this, `LogRetention${log}`, {
-          logGroupName: `/aws/rds/instance/${this.instanceIdentifier}/${log}`,
+          logGroupName,
           retention: this.cloudwatchLogsRetention,
           role: this.cloudwatchLogsRetentionRole,
         });
       }
     }
+    return logGroups;
   }
 }
 
@@ -1006,6 +1015,7 @@ export class DatabaseInstance extends DatabaseInstanceSource implements IDatabas
   public readonly dbInstanceEndpointPort: string;
   public readonly instanceEndpoint: Endpoint;
   public readonly secret?: secretsmanager.ISecret;
+  public readonly logGroups: logs.ILogGroup[];
 
   constructor(scope: Construct, id: string, props: DatabaseInstanceProps) {
     super(scope, id, props);
@@ -1036,7 +1046,7 @@ export class DatabaseInstance extends DatabaseInstanceSource implements IDatabas
       this.secret = secret.attach(this);
     }
 
-    this.setLogRetention();
+    this.logGroups = this.setLogRetention();
   }
 }
 
@@ -1073,6 +1083,7 @@ export class DatabaseInstanceFromSnapshot extends DatabaseInstanceSource impleme
   public readonly dbInstanceEndpointPort: string;
   public readonly instanceEndpoint: Endpoint;
   public readonly secret?: secretsmanager.ISecret;
+  public readonly logGroups: logs.ILogGroup[];
 
   constructor(scope: Construct, id: string, props: DatabaseInstanceFromSnapshotProps) {
     super(scope, id, props);
@@ -1113,7 +1124,7 @@ export class DatabaseInstanceFromSnapshot extends DatabaseInstanceSource impleme
       this.secret = secret.attach(this);
     }
 
-    this.setLogRetention();
+    this.logGroups = this.setLogRetention();
   }
 }
 
@@ -1161,6 +1172,7 @@ export class DatabaseInstanceReadReplica extends DatabaseInstanceNew implements
   public readonly dbInstanceEndpointPort: string;
   public readonly instanceEndpoint: Endpoint;
   public readonly engine?: IInstanceEngine = undefined;
+  public readonly logGroups: logs.ILogGroup[];
   protected readonly instanceType: ec2.InstanceType;
 
   constructor(scope: Construct, id: string, props: DatabaseInstanceReadReplicaProps) {
@@ -1197,7 +1209,7 @@ export class DatabaseInstanceReadReplica extends DatabaseInstanceNew implements
 
     instance.applyRemovalPolicy(props.removalPolicy ?? RemovalPolicy.SNAPSHOT);
 
-    this.setLogRetention();
+    this.logGroups = this.setLogRetention();
   }
 }
 
diff --git a/packages/@aws-cdk/aws-rds/test/instance.test.ts b/packages/@aws-cdk/aws-rds/test/instance.test.ts
index 8ddc2b92dd697..ae1dcfeb51517 100644
--- a/packages/@aws-cdk/aws-rds/test/instance.test.ts
+++ b/packages/@aws-cdk/aws-rds/test/instance.test.ts
@@ -1684,6 +1684,26 @@ describe('instance', () => {
       Engine: 'postgres',
     });
   });
+
+  test('If log output is enabled, expected logGroups Properties can be obtained', () => {
+    // GIVEN
+    const cloudwatchLogsExports = ['error', 'general', 'slowquery', 'audit'];
+
+    // WHEN
+    const instance = new rds.DatabaseInstance(stack, 'Instance', {
+      engine: rds.DatabaseInstanceEngine.mysql({ version: rds.MysqlEngineVersion.VER_8_0_26 }),
+      vpc,
+      cloudwatchLogsExports,
+      cloudwatchLogsRetention: logs.RetentionDays.ONE_MONTH,
+    });
+
+    // THEN
+    expect(instance.logGroups.length).toEqual(cloudwatchLogsExports.length);
+
+    instance.logGroups.forEach((logGroup, i) => {
+      expect(logGroup.logGroupName).toEqual(`/aws/rds/instance/${instance.instanceIdentifier}/${cloudwatchLogsExports[i]}`);
+    });
+  });
 });
 
 test.each([

From 7a590df575768d74f458e248f73150ce3b74d01e Mon Sep 17 00:00:00 2001
From: mokocm <mokocmmoko@gmail.com>
Date: Fri, 19 Aug 2022 17:59:56 +0900
Subject: [PATCH 2/2] Described in README about logGroups

---
 packages/@aws-cdk/aws-rds/README.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/packages/@aws-cdk/aws-rds/README.md b/packages/@aws-cdk/aws-rds/README.md
index 813a5f33dcca4..9c7ba57d98636 100644
--- a/packages/@aws-cdk/aws-rds/README.md
+++ b/packages/@aws-cdk/aws-rds/README.md
@@ -544,6 +544,10 @@ const instance = new rds.DatabaseInstance(this, 'Instance', {
   cloudwatchLogsExports: ['postgresql'], // Export the PostgreSQL logs
   // ...
 });
+
+instance.logGroups.foreach(logGroup => {
+  // You can get log group
+})
 ```
 
 ## Option Groups