probe failed: context deadline exceeded

[heidihe2024]

I'm using coroot-aws-agent, trying to monitor the postgres rds aurora instances, which

1. starts a pg db collector: https://github.com/coroot/coroot-aws-agent/blob/main/rds/collector.go#L125-L147. If I read it right, it ping the postgres DSN during this process: https://github.com/coroot/coroot-pg-agent/blob/main/collector/collector.go#L108-L113
2. Once confirmed that postgres collector started, it calls the pg-agent "collect" function, which also triggers a PING: https://github.com/coroot/coroot-pg-agent/blob/main/collector/collector.go#L325-L326 However, my system also failed at this step with "probe failed: context deadline exceeded".

I've tested in the coroot-aws-agent, trying to connect to db using psql "postgresql://user:password@ip:port/5432/postgres..". Everything works. Do you have any idea what I'm missing here?
Is it due to the https://github.com/coroot/coroot-pg-agent/blob/main/collector/collector.go#L108

c.db.SetMaxOpenConns(1)
	pingCtx, pingCancelFunc := context.WithTimeout(ctx, collectTimeout)

and keep the postgres connection?

Thank you for your time!