Order portal: zone loss, shared uploads, no rewrite

Challenge brief

A media operations team runs a three-tier order portal on EC2 in a single Availability Zone; customer uploads are written to instance-local EBS volumes and a self-managed MySQL 8.0 server runs on a separate EC2 host. An Availability Zone impairment last quarter took the portal offline for four hours, and the team restored from the previous night's logical dump. The portal must survive the loss of one Availability Zone, database failover may lose no more than a few seconds of committed writes, and every web instance must read and write one shared upload directory. The team will not rewrite SQL statements or POSIX file paths, and multi-Region disaster recovery stays out of scope this budget cycle. Which design meets every requirement with the least change to the application code?

Success criteria

• 1.Add an Application Load Balancer as the single entry point for the web tier.
• 2.Add an Auto Scaling group so web capacity is replaced and rebalanced without an operator.
• 3.Add an RDS Multi-AZ DB instance so MySQL has a synchronous standby in a second Availability Zone.
• 4.Add one Regional EFS file system so every web instance mounts the same upload directory.
• 5.Connect the load balancer to the Auto Scaling group and the Auto Scaling group to the database.
• 6.Connect the Auto Scaling group to the file system so the uploads are shared.
• 7.Place the Auto Scaling group in two Availability Zones.
• 8.Leave AWS Elastic Disaster Recovery out; this is an in-Region availability requirement, not a Regional recovery one.

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