Amazon MQ with active/standby brokers configured across two AZ ensures high availability for the message broker. In case of a failure in one AZ, the other AZ's broker can take over seamlessly.
Adding an ASG for the consumer EC2 instances across two AZ provides redundancy and automatic scaling based on demand. If one consumer instance becomes unavailable or if the message load increases, the ASG can automatically launch additional instances to handle the workload.
Using RDS for MySQL with Multi-AZ enabled ensures high availability for the database. Multi-AZ automatically replicates the database to a standby instance in another AZ. If a failure occurs, RDS automatically fails over to the standby instance without manual intervention.
This architecture combines high availability for the message broker (Amazon MQ), scalability and redundancy for the consumer EC2 instances (ASG), and high availability for the database (RDS Multi-AZ). It offers the highest availability with low operational complexity by leveraging managed services and automated failover mechanisms.