The plugin does not work if Vault is running on a container, based on official HashiCorp image hashicorp/vault:1.12.1 (which is derived by Alpine Linux)

[denismaggior8]

After having copied the plugin on the Vault's plugin directory and having registered it (everything worked so far), when you enable the secret engine an error occurs:

$ vault secrets enable enigma

Error enabling: Error making API request.

URL: POST http://localhost:8200/v1/sys/mounts/enigma
Code: 400. Errors:

* invalid backend version: 2 errors occurred:
        * fork/exec /usr/local/libexec/vault/enigma.1.0.0: no such file or directory
        * fork/exec /usr/local/libexec/vault/enigma.1.0.0: no such file or directory

Please don't get confused by the "no such file or directory" error, the plugin is there named correctly enigma.1.0.0

$ kubectl exec -ti vault-0 -n vault -- ls -l /usr/local/libexec/vault/enigma.1.0.0
-rwxr-xr-x    1 vault    vault     15803651 Feb 21 08:51 /usr/local/libexec/vault/enigma.1.0.0

I supposed this is related to the fact that Alpine Linux relies on MUSL LIBC instead of the GNU LIBC.