https://www.percona.com/resources/webinars/enterprise-grade-...
Like some people mentioned - you could Patroni for HA. It is a template that could be configured with etcd like distributed consensus key value stores for leader election using the world famous RAFT algorithm. Could use Watchdog/Softdog for avoiding split-brain. Now, we could also do some actions before and after failover which can be scripted. Regarding HA on other pieces such as Blob store, you could use CRR using the AWS S3. You could just mount the S3 via NFS Gateway to DB servers and let the job be done in a more simpler way. Similarly, all the problems you mentioned are solved, however, anything you feel is still challenging after going through the webinar recording, please reply back here.