Postgresql – Why can’t I create a superuser in AWS Postgresql instance

amazon-rdsamazon-web-servicespostgresql

I have an AWS EC2 instance connecting to an RDS instance (Postgresql). When I created the RDS instance, I told it the DB root's username was: my_user1 and the password was password1. Now I'm attempting to create a role and a super-user. But it fails:

$ createuser -P -d -s -e my_user2 --host myhost.com -U my_user1
Enter password for new role: XXXYYYZZZ
Enter it again: XXXYYYZZZ
Password: password1
CREATE ROLE my_user2 PASSWORD 'md5999999c0101a1d64afd57575e06f999c' SUPERUSER CREATEDB  CREATEROLE INHERIT LOGIN;
createuser: creation of new role failed: ERROR:  must be superuser to create superusers
$

When I repeat the command without the -s flag, it works:

$ createuser -P -d -e my_user2 --host myhost.com  -U my_user1
Enter password for new role:
Enter it again:
Password:
CREATE ROLE my_user2 PASSWORD 'md5999999c0101a1d64afd57575e06f888c' NOSUPERUSER CREATEDB NOCREATEROLE INHERIT LOGIN;
$

So clearly, my_user1 doesn't have permissions to create a super-user. But this is the user I told RDS was my admin user! If my_user1 doesn't have permissions to create a super-user, who does? And how do I get their username/password from AWS?

Best Answer

RDS instances are managed by Amazon. As such, to prevent you from breaking things like replication, your users - even the root user you set up when you create the instance - will not have full superuser privileges.

http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.PostgreSQL.CommonDBATasks.html

When you create a DB instance, the master user system account that you create is assigned to the rds_superuser role. The rds_superuser role is a pre-defined Amazon RDS role similar to the PostgreSQL superuser role (customarily named postgres in local instances), but with some restrictions. As with the PostgreSQL superuser role, the rds_superuser role has the most privileges on your DB instance and you should not assign this role to users unless they need the most access to the DB instance.

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