Bug: workshop snap installation creates zpool, breaking zfs-cache-import.service and existing zpool mounts

*Please describe the question or issue you're facing with "Get started with workshops".*

```
jehos@gogunbuntu:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 26.04 LTS
Release: 26.04
Codename: resolute

jehos@gogunbuntu:~$ uname -a
Linux gogunbuntu 7.0.0-15-generic #15-Ubuntu SMP PREEMPT_DYNAMIC Wed Apr 22 16:06:43 UTC 2026 x86_64 GNU/Linux

jehos@gogunbuntu:~$ snap list {workshop,lxd}
이름 버전 개정 추적 발행인 노트
lxd 6.8-5a1a287 39313 6/stable canonical✓ -
workshop 0.9.0-69ab7c1 147 latest/stable dlyfar classic

jehos@gogunbuntu:~$ date
2026. 05. 28. (목) 17:21:48 KST

jehos@gogunbuntu:~$ zpool status
pool: DATA0
state: ONLINE
scan: scrub repaired 0B in 00:00:34 with 0 errors on Sun May 10 00:24:35 2026
config:

NAME STATE READ WRITE CKSUM
DATA0 ONLINE 0 0 0
nvme0n1p4 ONLINE 0 0 0

errors: No known data errors

pool: rpool
state: ONLINE
scan: scrub repaired 0B in 00:06:15 with 0 errors on Sun May 10 00:30:17 2026
config:

NAME STATE READ WRITE CKSUM
rpool ONLINE 0 0 0
nvme1n1p3 ONLINE 0 0 0

errors: No known data errors

pool: workshop
state: ONLINE
config:

NAME STATE READ WRITE CKSUM
workshop ONLINE 0 0 0
/var/snap/lxd/common/lxd/disks/workshop.img ONLINE 0 0 0

errors: No known data errors

jehos@gogunbuntu:~$ zfs list
NAME USED AVAIL REFER MOUNTPOINT
DATA0 34.0G 197G 24K /DATA0
DATA0/docker 15.8G 197G 15.8G /var/lib/docker
DATA0/ollama 18.1G 197G 18.1G /usr/share/ollama
rpool 338G 446G 34K /rpool
rpool/apt-cacher-ng 452M 446G 452M /var/cache/apt-cacher-ng
rpool/home 329G 446G 232G /home
rpool/libvirt 24K 446G 24K /var/lib/libvirt/images
rpool/logs 818M 446G 24K /rpool/logs
rpool/logs/syslog 818M 446G 818M /var/log
rpool/var-lib-rancher 6.86G 446G 6.70G /var/lib/rancher/
rpool/vector 24K 446G 24K /var/lib/vector
workshop 556K 28.6G 24K legacy
workshop/containers 24K 28.6G 24K legacy
workshop/custom 24K 28.6G 24K legacy
workshop/deleted 120K 28.6G 24K legacy
workshop/deleted/containers 24K 28.6G 24K legacy
workshop/deleted/custom 24K 28.6G 24K legacy
workshop/deleted/images 24K 28.6G 24K legacy
workshop/deleted/virtual-machines 24K 28.6G 24K legacy
workshop/images 24K 28.6G 24K legacy
workshop/virtual-machines 24K 28.6G 24K legacy
```

Here is a clear, professionally structured bug report ready to be submitted to Canonical's Launchpad, GitHub, or their dedicated issue tracker.

---

### **Issue Title**

**Bug: `workshop` snap installation creates zpool, breaking `zfs-cache-import.service` and existing zpool mounts**

### **Description**

Installing the newly released `workshop` via Snap automatically creates a zpool named `workshop`. However, this process unexpectedly breaks the ZFS cache. On subsequent boot, `zfs-cache-import.service` fails, preventing other existing zpools from loading automatically.

In environments where ZFS is heavily utilized for the system layout (e.g., hosting `/home` and most directories outside of `rootfs` on ZFS), this bug is critical. The failure to mount the pool containing the user directories results in a broken login screen and renders user accounts unusable.

### **Steps to Reproduce**

1. Configure an Ubuntu system with existing ZFS pools (e.g., mounting user directories like `/home`).
2. Install the workshop snap package (`sudo snap install workshop`).
3. Notice the automatic creation of the `workshop` zpool.
4. Reboot the system.
5. Attempt to log in from the display manager.

### **Expected Behavior**

The `workshop` snap should create its required zpool while gracefully updating the `zpool.cache`. It should not interfere with `zfs-cache-import.service`, and all previously existing zpools should mount normally during the boot process.

### **Actual Behavior**

The creation of the `workshop` zpool causes `zfs-cache-import.service` to fail. Existing zpools do not mount at boot. If critical system paths (like `/home`) are on these unmounted pools, the user cannot log in or use the system properly.

### **Workaround / Remediation**

To recover the system and prevent the issue from persisting across reboots, the following manual intervention is required:

1. At the broken graphical login screen, switch to a virtual terminal (TTY) by pressing `Ctrl` + `Alt` + `F2`.
2. Log in and escalate privileges via `sudo`.
3. Manually import the existing pools using the `zfs import` command.
4. Regenerate the ZFS cache by restarting the import service:

```bash
sudo systemctl restart zfs-cache-import.service

```

*Note: If the `zfs-cache-import.service` is not restarted to rebuild the cache, the system will fail to load the pools again on the next reboot.*

### **Environment Details**

* **Package:** `workshop` (Snap)
* **Impacted Service:** `zfs-cache-import.service`
* **System Layout:** `rootfs` on standard partition, remaining directories (including `/home`) on ZFS.

---
*Reported from: https://documentation.ubuntu.com/canonical-workshop/latest/tutorial/part-1-get-started/*