Reason for architecture:

chosen microservice. Separate Auth/Resource servers. Admin FE separate service. Implementation includes only resource server.
separate cache server for keeping the load mentioned in the task, allowing horizontal scaling. Only used by admin part of service
MySQL as persistence layer. No specific requirements in the task, one of those easier to work with.
containerizing with docker, allowing for automated CI/CD.
GitHub - VCS solution.
GitHub Actions - automated build, containerizing, pushing to docker hub.
Spring Boot main framework
Spring Security and Spring OAuth2 Resource Server authentication/authorization management
Spring Cloud properties refresh (Cloud Config server not implemented)

Risks:

no logging or monitoring setup (no requirements)
security config is for demo
db volume is not externalized from container intentionally
if project will grow admin part might be separated from client-facing part to another microservice
@RefreshScope not activated due to lack of Cloud Config server

Source-code:

https://github.com/lvvorovi/bookstore-nine

Pre-compiled package:

containerized https://hub.docker.com/r/lvvorovi/bookstore/tags - 9.
package https://github.com/lvvorovi/bookstore-nine/blob/master/nine-2.0.jar

Set-up guide:

able to run, but unable to use. All endpoints secured, except /swagger-ui/index.html and /actuator/refresh.
use docker compose -f compose9.yaml up with https://github.com/lvvorovi/bookstore-nine/blob/master/compose9.yaml

Note:

considered unfinished due to lack of time.