Accessing RDS from within a Docker container not getting through security group?

Question

I\'m attempting to run a webserver that uses an RDS database with EC2 inside a docker container.

I\'ve setup the security groups so the EC2 host\'s role is allowed

Answer 1

When I tried to connect to AWS RDS in inside of docker container, I got "Access denied for user 'username'@'xxx.xx.xxx.x' (using password: YES)" error. To solve this issue, I did below two ways:

1. I created new user and assigned grant.

   $ CREATE USER 'newuser'@'%' IDENTIFIED BY 'password';
   $ GRANT ALL ON newuser@'%' IDENTIFIED BY  'password';
   $ FLUSH PRIVILEGES;
   

2. Added global DNS address 8.8.8.8 into docker container when run docker, so that the docker container can resolve IP address of AWS RDS from domain name.

   $ docker run --name backend-app --dns=8.8.8.8 -p 8000:8000 -d backend-app
   

Then I connected from inside of docker container to AWS RDS, successfully.

• Note: Firstly, I tried second way. But I didn't solve the connection problem. When I tried both two ways, I was success.