AWS RDS DBProxyTarget unavailable with "Waiting for proxy to scale to desired capacity"

Question

I was following this tutorial to connect to an RDS(deployed on AWS) via a proxy.

However, after creation of the proxy through AWS console, the TargetGroup remained unavailable(for well over 4 hours) A stackoverflow answer suggested describing the proxy target using

aws rds describe-db-proxy-targets --db-proxy-name <proxyname>

The output of which was

{
    "Targets": [
        {
            "Endpoint": "abcd-efg.hijklmnop.us-east-9.rds.amazonaws.com",
            "RdsResourceId": "abcd-efg",
            "Port": 3306,
            "Type": "RDS_INSTANCE",
            "Role": "UNKNOWN",
            "TargetHealth": {
                "State": "UNAVAILABLE",
                "Reason": "PENDING_PROXY_CAPACITY",
                "Description": "DBProxy Target is waiting for proxy to scale to desired capacity"
            }
        }
    ]
}

Trying to login to the RDS using the proxy was of little help

$ mysql -h abcd-efg.hijklmnop.us-east-9.rds.amazonaws.com -P 3306 -u <username> -p
Enter password:
ERROR 2013 (HY000): Lost connection to MySQL server at 'reading initial communication packet', system error: 0

However, I can access the DB using the db's private endpoint. Access via proxy fails. I dug through a lot of troubleshooting and other pages, but none offered solutions to the description "DBProxy Target is waiting for proxy to scale to desired capacity". Any inputs on the same?

Answer 1

You can try to enable enhanced logging of the proxy and check the logs in Cloudwatch. In my case, it was because the IAM role that I assigned to the proxy doesn't allow sts:AssumeRole from principal "Service": "rds.amazonaws.com"