AWS RDS MySQL connection using IAM Role is not working - amazon-rds

Question

Would like to inform upfront that I am new to AWS in general. For my project I am trying to use AWS RDS MySQL using IAM Authentication (IAM Role) from a Java application deployed on Tomcat on an EC2 instance. Before trying it from Java I am trying it from the command prompt on the EC2 instance. I am following this link to do it:
https://aws.amazon.com/premiumsupport/knowledge-center/users-connect-rds-iam/
I have done the following so far (please pardon if I am not using correct terminologies):
MySQL using AWS RDS
Enabled IAM Authentication on my MySQL instance
Created IAM Role for EC2
Created an inline policy for the above IAM Role and granted required "Action". Also included the "Resources" (my database's endpoint with username), as below:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"rds-db:connect"
],
"Resource": [
"arn:aws:rds-db:<my-region>:<my-account-id>:dbuser:<my-db-resource-id>/<my-db-username>"
]
}
]
}
Assigned this IAM Role to an EC2 instance I have created
I followed everything given in the link at the top and everything seem to work except for the last command.
As in the link I created DB user as below:
CREATE USER dev_user IDENTIFIED WITH AWSAuthenticationPlugin as 'RDS';
The last command in the link that is not working is:
mysql -h {db or cluser endpoint} --ssl-ca={certificate file name with complete path} --ssl-verify-server-cert -u {dbusername2} -p"{authenticationtoken}" --enable-cleartext-plugin
Every time I run this command it asks for the password and then I am getting an error. I am at a loss on how to resolve it.
In the above mysql command if I pass my master user-id (I created it as 'admin') and enter it's password I get an error like this:
[ec2-user#ip-xxx-xx-xx-16 ~]$ mysql -h <endpoint of my RDS DB instance> --ssl-ca=rds-combined-ca-bundle.pem --ssl-verify-server-cert -u admin -p 'aws rds generate-db-auth-token --hostname <endpoint of my RDS DB instance> --port 3306 --username dev_user' --enable-cleartext-plugin
Enter password:
ERROR 1059 (42000): Identifier name 'aws rds generate-db-auth-token --hostname --port' is too long
And if in the same command I provide the above created DB user (dev_user). I get the following error if provide "dev_user" as user in the command and whether I enter a password or not. [In this case, the above link did not set a password so what should I do when it asks to enter the password?]:
[ec2-user#ip-xxx-xx-xx-16 ~]$ mysql -h <endpoint of my RDS DB instance> --ssl-ca=rds-combined-ca-bundle.pem --ssl-verify-server-cert -u dev_user -p 'aws rds generate-db-auth-token --hostname <endpoint of my RDS DB instance> --port 3306 --username dev_user' --enable-cleartext-plugin
Enter password:
ERROR 1045 (28000): Access denied for user 'dev_user'#'xxx.xx.xx.16' (using password: YES)
I get the same "Access denied..." error when I enter "admin" in both places in the command above.
Any help will be highly appreciated.
Thank you.

Answer 1

First of all, there shouldn't be space after -p parameter.
Second, if you want to execute aws rds generate-db-auth-token... inline, it should be marked with ticks, not single quotes.
mysql -h <endpoint of my RDS DB instance> --ssl-ca=rds-combined-ca-bundle.pem --ssl-verify-server-cert -u dev_user -p`aws rds generate-db-auth-token --hostname <endpoint of my RDS DB instance> --port 3306 --username dev_user` --enable-cleartext-plugin