Run a Lambda function for RDS using the DBInstanceIdentifier

Hello,

I have been trying to automate stopping RDS instance using a Lambda Function when the number of connections made to the instances are low than 1. I have used an EventBridge that triggers the Lambda function when the Alarm created goes into In Alarm.

From this, it stops all the RDS instances even those with connections. I understand that the issue is in the Lambda function since it loops through all instances and turns them off.

I was inquiring if there is a way to pass the DBInstanceIdentifier of the instance in alarm state only to the lambda function for it to only shut down the instance in which the alarm is on.

Below is the lambda code used.

import boto3 import os

target_db = None region = os.environ['AWS_REGION'] rds = boto3.client('rds', region_name=region)

def get_tags_for_db(db): instance_arn = db['DBInstanceArn'] instance_tags = rds.list_tags_for_resource(ResourceName=instance_arn) return instance_tags['TagList']

def get_tags_for_db_cluster(db): instance_arn = db['DBClusterArn'] instance_tags = rds.list_tags_for_resource(ResourceName=instance_arn) return instance_tags['TagList']

def lambda_handler(event, context):

dbs = rds.describe_db_instances()
readReplica = []
for db in dbs['DBInstances']:
    readReplicaDB = db['ReadReplicaDBInstanceIdentifiers']
    readReplica.extend(readReplicaDB)
print("readReplica : " + str(readReplica))

for db in dbs['DBInstances']:
    db_id = db['DBInstanceIdentifier']
    db_engine = db['Engine']
    print('DB ID : ' + str(db_id))
    db_tags = get_tags_for_db(db)
    print("All Tags : " + str(db_tags))
    tag = next(iter(filter(lambda tag: tag['Key'] == 'AutoStop' and tag['Value'].lower() == 'true', db_tags)), None)
    print("AutoStop Tag : " + str(tag))

    if db_engine not in ['aurora-mysql','aurora-postgresql']:
        if db_id not in readReplica and len(readReplica) == 0:
            if tag:
                target_db = db
                print("DB Details : " + str(target_db))
                db_id = target_db['DBInstanceIdentifier']
                db_status = target_db['DBInstanceStatus']
                print("DB ID : " + str(db_id))
                print("DB Status : " + str(db_status))
                if db_status == "available":
                    AutoStopping = rds.stop_db_instance(DBInstanceIdentifier=db_id)
                    print("Stopping DB : " + str(db_id))
                else:
                    print("Database already stopped : " + str(db_id))
            else:
                print("AutoStop Tag Key not set for Database to Stop...")
        else:
            print("Cannot stop or start a Read-Replica Database...")

dbs = rds.describe_db_clusters()
readReplica = []
for db in dbs['DBClusters']:
    readReplicaDB = db['ReadReplicaIdentifiers']
    readReplica.extend(readReplicaDB)
print("readReplica : " + str(readReplica))

for db in dbs['DBClusters']:
    db_id = db['DBClusterIdentifier']
    db_engine = db['Engine']
    print('DB ID : ' + str(db_id))
    db_tags = get_tags_for_db_cluster(db)
    print("All Tags : " + str(db_tags))
    tag = next(iter(filter(lambda tag: tag['Key'] == 'AutoStop' and tag['Value'].lower() == 'true', db_tags)), None)
    print("AutoStop Tag : " + str(tag))

    if db_engine in ['aurora-mysql','aurora-postgresql']:
        if db_id not in readReplica and len(readReplica) == 0:
            if tag:
                target_db = db
                db_id = target_db['DBClusterIdentifier']
                db_status = target_db['Status']
                print("Cluster DB ID : " + str(db_id))
                print("Cluster DB Status : " + str(db_status))
                if db_status == "available":
                    AutoStopping = rds.stop_db_cluster(DBClusterIdentifier=db_id)
                    print("Stopping Cluster DB : " + str(db_id))
                else:
                    print("Cluster Database already stopped : " + str(db_id))
            else:
                print("AutoStop Tag Key not set for Cluster Database to Stop...")
        else:
            print("Cannot stop or start a Read-Replica Cluster Database...")