So what’s the way to correctly mount a postgresql volume using Aws EBS
You are on a right path…
Error you get is because you want to use root folder of mounted volume / as postgresql Data dir and postgresql complains that it is not best practice to do so since it is not empty and contains already some data inside (namely lost+found directory).
It is far better to locate data dir in separate empty subfolder (/postgres for example) and give postgresql clean slate when creating its file structure. You didn’t get same thing on minicube since you most probably mounted host folder that didn’t have anything inside (was empty) and didn’t trigger such a complaint.
To do so, you would need initially empty subPath of your volume (empty /postgres subfolder on your PV for example) mounted to appropriate mount point (/var/lib/posgresql/data) in your pod. Note that you can name subPath and mount point end folder the same name, they are different here just as an example where test-db-volume/postgres folder would be mounted on pod to /var/lib/postgresql/data folder:
...
volumeMounts:
- mountPath: /var/lib/postgresql/data
name: test-db-volume
subPath: postgres
...