Hi Arun,
First of all, thank you so much for your time and explanation.
Maybe we're doing wrong the process. The truth is that I (we) never did this before. We want to configure AppDynamics in an Amazon RDS MySQL instance. Amazon does not let you install anything on DB, so no DB agent is installed. This means that no DB_agent can be started and no DB_agent logs are available, so we won't be able to attach any agent.log.
What we have done, so far, is to configure the MySQL RDS instance in Amazon side. It is done to use a DB in a cloud environment in Amazon AWS, to ease management and throughput issues in AWS (but I'm sure you also know this). It doesn't matter if you will be using AppDynamics later or not...
After that, in AppDynamics Controller, we acceeded Databases menu and added a new Collector. We have to add that we didn't see such UI that is shown in "Step 1" from section "Monitor Your Database With AppD4DB" in https://blog.appdynamics.com/database/how-to-set-up-and-monitor-amazon-rds-databases/ (We understand that this AppD4DB design is only a matter of UI). We have to add, also, that we have never seen any AppD4DB reference anywhere inside the Controller.
Anyway, to avoid confusing ourselves, what about if we start again from the beginning? We have the RDS MySQL instance configured, no possibility to install any DB_agent... next step?
Once more, thank you.
BR,
David.