[ { "role": "user", "content": "if%20we%20use%20zfs%20for%20our%20lxd%20storage%20on%20debian%2012%2C%20we%20can%27t%20access%20container%20files%20from%20the%20host%20the%20way%20we%20can%20if%20they%20use%20dir%20format%20(I%20think%20that%20is%20what%20it%20is%20called).%20If%20so%2C%20what%20is%20the%20recommended%20way%20of%20accessing%20the%20container%27s%20files%3F" }, { "role": "assistant", "content": "You\u2019re correct: when LXD uses ZFS as its storage driver, container root filesystems are managed via namespaced mounts. From the host\u2019s normal namespace, the mount points often appear empty, even though container files are underneath them. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/explanation/storage/?utm_source=openai))\n\nHere are the ways you can access container files when using ZFS, along with what is recommended under Debian 12 / modern LXD setups:\n\n---\n\n## \ud83e\uddd0 Why the \u201cempty\u201d directories\n\n- When LXD creates a container with ZFS, it sets up *datasets* under the ZFS pool. Each container has a dataset (filesystem) which is mounted via LXD, but that mount lives in a private mount namespace, not visible to the host by default. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/explanation/storage/?utm_source=openai)) \n- So even though `zfs list` will show the dataset and its mountpoint, entering that directory on the host often shows nothing (or only the empty container directory) because the rootfs is mounted only inside LXD\u2019s namespace. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/lxd-with-zfs-where-is-my-file/10066?utm_source=openai))\n\n---\n\n## \u2705 Correct ways to access the files from the host\n\nHere are the usual, recommended methods:\n\n1. **Use `lxc file`**\n\n - From the host, you can run:\n ```\n lxc exec -- ls /path/inside/container\n lxc file pull /path/to/file /host/path\n lxc file push /host/path /path/in/container\n ```\n - This uses the LXD API and works regardless of storage driver, permissions, or namespaces. It\u2019s safe and reliable. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/explanation/storage/?utm_source=openai))\n\n2. **Enter the LXD mount namespace**\n\n If you need direct access (for debugging, cleaning up, etc.), you can:\n\n - Find the LXD daemon\u2019s PID:\n ```\n cat /var/lib/lxd.pid # or if using snap: /var/snap/lxd/common/lxd.pid\n ```\n - Enter its mount namespace:\n ```\n sudo nsenter -t -m\n ```\n - Then navigate to the container\u2019s rootfs under the ZFS mountpoint (in the storage pool):\n ```\n cd /var/lib/lxd/storage-pools//containers//rootfs\n ```\n - Then you\u2019ll see all the files. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/can-i-access-a-containers-files-in-a-zfs-partition-from-host-cannot-run-container-due-to-error/15370?utm_source=openai))\n\n3. **Bind-mount or disk device into container**\n\n If you want certain host directories (or ZFS datasets) visible inside containers (e.g. for sharing data), you can configure LXD to mount host paths or datasets as `disk` devices in the container configuration. Permissions & UID/GID mappings will matter here. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/explanation/storage/?utm_source=openai))\n\n4. **Use ZFS dataset delegation (if ZFS version and LXD support it)**\n\n From OpenZFS 2.2 onward, there is support for *delegation*, where the container can be given control over its dataset (to manage snapshots, properties, etc.). Enabling `zfs.delegate=true` on containers or volumes makes some aspects more visible/usable inside the container. ([discourse.ubuntu.com](https://discourse.ubuntu.com/t/accessing-hosts-zfs-inside-an-lxd-container/63329?utm_source=openai))\n\n---\n\n## \ud83d\udee0 What\u2019s generally recommended with Debian 12 + current LXD\n\nIf you are on Debian 12 (which supports recent versions of ZFS and LXD), here\u2019s what tends to be the best practice:\n\n- Use ZFS for its benefits (snapshots, clones, quotas) unless you need really simple host\u2010side access to container files all the time.\n- For occasional access (debug, cleanup, backups), use `nsenter` into the LXD mount namespace. Keep in mind that requires root privilege on the host.\n- For frequent or programmatic access (e.g. backups, automation), prefer using `lxc file` commands or even `lxc exec` to run commands in container.\n- If sharing data (volume), create a custom storage volume or use a `disk` device or mount a ZFS dataset shared across both host and container, with appropriate permissions mapping.\n- If you need more control inside containers (e.g. snapshotting), and your ZFS version supports it, enable delegation (`zfs.delegate=true`). But only do this if you need the container to manage the dataset.\n\n---\n\nIf you want, I can walk you through how to set up some example configurations on Debian 12 that give you both ZFS benefits *and* easy host-side access." }, { "role": "user", "content": "you%20said%20not%20visible%20to%20the%20host%20by%20default.%20how%20to%20make%20visible%20by%20default%3F" }, { "role": "assistant", "content": "There\u2019s no officially supported way to make container root filesystems mounted under ZFS *always* visible in the host\u2019s default (root) mount namespace *if* you\u2019re using the Snap version of LXD, because it intentionally isolates container mounts using a separate mount namespace. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai))\n\nHowever, there *are* a few approaches/workarounds you can choose from, depending on your policy needs and how much control over your setup you have. Here are the main options:\n\n---\n\n## \u2699\ufe0f Workarounds & Alternatives\n\n### 1. Use the snap\u2019s hidden \u201cmntns\u201d gateway path\n\nSnap LXD provides a special path inside `/var/snap/lxd/common/mntns/...` which is a mount namespace alias. It allows you to view the container rootfs from the host by going through that path. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai))\n\nFor example:\n\n```\nsudo ls /var/snap/lxd/common/mntns/var/snap/lxd/common/lxd/storage-pools//containers//rootfs\n```\n\nThis path mirrors the container mounts when they are active. It\u2019s how Snap handles visibility for backups, audits, etc. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai))\n\n### 2. Enter the LXD mount namespace (`nsenter`)\n\nYou can use `nsenter` to access the mount namespace that LXD is using, which will show you the container fss directly:\n\n```bash\nsudo nsenter --mount=/run/snapd/ns/lxd.mnt -- ls /var/snap/lxd/common/lxd/storage-pools//containers//rootfs\n```\n\nThis exposes the full container rootfs, same as inside the container. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/lxd-with-zfs-where-is-my-file/10066?utm_source=openai))\n\n### 3. Install LXD without snap (Deb / Source)\n\nIf you install LXD outside of Snap (for example via Debian\u2019s package repositories or by building from source), you avoid the mount namespace behavior\u2014so container rootfs mounts show up in the host\u2019s standard mount namespace. ([bobcares.com](https://bobcares.com/blog/lxd-debian-without-snap/?utm_source=openai))\n\nThis gives you \u201cnormal\u201d visibility:\n\n- `/var/lib/lxd/storage-pools/.../containers/.../rootfs/...` will directly show the files from the host without needing `nsenter` or the `mntns` gateway.\n- But you lose some isolation and maybe some conveniences that Snap provides.\n\n---\n\n## \ud83d\udee1 Considerations & Trade-offs\n\n- **Security / Isolation**: The mount namespace separation is there for a reason\u2014better isolation. Making mounts visible in the host namespace leaks container internals into the host, possibly creating security issues.\n\n- **Permissions & UID mapping**: With ZFS + Snap LXD + unprivileged containers, UID/GIDs inside the container may map to large offset IDs on the host. Even when visible, files can appear owned by high numeric IDs (outside 0\u201365535), making permissions awkward. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/lxd-with-zfs-where-is-my-file/10066?utm_source=openai))\n\n- **Support & Maintenance**: Snap\u2019s behavior (namespaced mounts) is baked in. Changing that behavior at system level isn\u2019t supported and could break during updates. Installing via apt/source makes more sense if you need host-side access frequently.\n\n---\n\n## \u2705 What\u2019s \u201cRecommended\u201d If You Want Default Host Visibility\n\nGiven those trade-offs, here\u2019s what I'd recommend in Debian 12:\n\n- If you need frequent direct host visibility (for e.g. backups, monitoring, audits), install LXD using Debian\u2019s packages or from source\u2014not via Snap. That removes the mount namespace barrier. \n\n- If you stick with Snap LXD (which many do for stability and easier updates), use the `mntns` path or `nsenter` approach when you need visibility. Possibly script it.\n\n- Also consider sharing data via LXD device mappings (`lxc config device add \u2026 disk`) if you want specific directories on the host visible in the container\u2014and ensure IDs are mapped correctly via `raw.idmap`, etc. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/userns-idmap/?utm_source=openai))\n\n---\n\nIf you like, I can walk you through converting an existing Snap-based LXD installation to a non-snap version in Debian 12 so that you get this host visibility by default. Do you want me to send you that?" }, { "role": "user", "content": "I%27m%20not%20using%20ubuntu%20or%20snaps.%20i%27m%20on%20debian%2012.%20i%20could%20go%20to%20debian%2013.%20i%20want%20to%20be%20able%20to%20view%20zfs%20files%20on%20the%20containers" }, { "role": "assistant", "content": "If you're using Debian 12 (Bookworm) or Debian 13 (Trixie), *without* Snap, then LXD is packaged natively, and it behaves differently than the Snap-based version regarding mount namespaces. That means container root filesystems *do* appear in the host namespace\u2014so you *can* see them at `/var/lib/lxd/...` (or wherever your storage-pools are) as soon as the container is running. ([wiki.debian.org](https://wiki.debian.org/LXD?utm_source=openai))\n\nHere\u2019s what you need to know, and how to ensure you get the visibility you want.\n\n---\n\n## \u2705 Native Debian LXD vs Snap LXD\n\n- Debian provides LXD as an **APT package** in Bookworm and newer releases. If you install via `apt install lxd` (plus `zfsutils-linux` if using ZFS), you're using the non-Snap version. ([wiki.debian.org](https://wiki.debian.org/LXD?utm_source=openai))\n- The non-Snap version **does not isolate** container rootfs mounts into a separate mount namespace. So mounts are visible from the host\u2019s normal filesystem tree. By contrast, the Snap version *does* isolate them, hiding them from the host unless you go into the mount namespace. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/lxd-with-zfs-where-is-my-file/10066?utm_source=openai))\n\n---\n\n## \ud83d\udee0 Making sure your setup shows container files\n\nTo make sure you can see container files on your host by default:\n\n1. **Install LXD from Debian\u2019s package repo**, not via Snap.\n\n ```bash\n sudo apt update\n sudo apt install lxd zfsutils-linux\n ```\n\n If you currently have a Snap version of LXD or ZFS installed by Snap, you\u2019ll need to completely remove it. Confirm LXD is running as a standard systemd service, not from Snap. (Check `which lxd` and `lxd --version`.)\n\n2. **Initialize LXD and configure ZFS properly**\n\n ```bash\n sudo lxd init\n ```\n\n During setup, when asked about your storage backends, choose ZFS and select/create your zpool. Debian\u2019s version of LXD supports full ZFS features. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/reference/storage_zfs/?utm_source=openai))\n\n3. **Verify mountpoints show from host**\n\n Once a container is running:\n\n - Use `zfs list` to confirm LXD datasets and mountpoints. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/reference/storage_zfs/?utm_source=openai))\n - Check on the host filesystem under `/var/lib/lxd/storage-pools//containers//rootfs` (or equivalent depending on your storage-pool name). You should see the container\u2019s filesystem there.\n\n4. **Ensure correct UID/GID mapping for unprivileged containers**\n\n If your containers are unprivileged (the default), the filesystem on the host will show UID/GIDs from your host mapping, which might be large numbers (e.g. starting at 100000). The ownership will look odd but that\u2019s normal. To make data shared nicely, consider using `raw.idmap` or shared user namespaces. ([documentation.ubuntu.com](https://documentation.ubuntu.com/lxd/latest/userns-idmap/?utm_source=openai))\n\n---\n\n## \u26a0\ufe0f If currently using a setup that\u2019s hiding files (e.g. Snap or weird mounts)\n\nIf you currently are unable to see the container files:\n\n- Confirm whether **LXD is installed as a Snap or via apt**. If it's Snap, the behavior of \u201cmount namespace hiding\u201d is normal. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai))\n- If you want default visibility, **migrate to the apt-based LXD** in Debian. That usually means stopping Snap\u2019s LXD and cleaning up, then installing the Debian LXD.\n- When migrating, back up container data first (using `lxc export`, snapshots, etc.).\n\n---\n\nIf you like, I can help you check your current LXD install (on Debian 12) and show exactly how to migrate to a package\u2010based version so your container files are visible by default." }, { "role": "user", "content": "so%20i%20can%27t%20see%20my%20files%20unless%20the%20container%20is%20running%3F" }, { "role": "assistant", "content": "Yes \u2014 whether the container is running *does* affect whether its root filesystem is mounted (and therefore visible) from the host. Depending on which version of LXD you're using, here's what typically happens:\n\n---\n\n## \ud83d\udd0d Behavior for non-Snap LXD (Debian\u2019s apt package version)\n\nIf you're using the non-Snap version of LXD (e.g. on Debian 12 or 13), container datasets are mounted when the container is **started**, and unmounted when the container is **stopped**. That means:\n\n- When *running*, the ZFS dataset for the container\u2019s rootfs will appear at its mountpoint (e.g. `/var/lib/lxd/storage-pools//containers//rootfs`). \n- When *stopped*, that dataset is unmounted, so that directory may appear empty (though the dataset still exists in `zfs list`).\n\n---\n\n## \u26a0\ufe0f Behavior for Snap-based LXD (less relevant since you\u2019re not using it, but good context)\n\n- Snap-LXD uses a separate mount namespace, which hides container rootfs mounts from the main host namespace except when you explicitly look through the namespace or enter it via `nsenter` or via the `mntns` gateway. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai)) \n- Even when containers are running, without Snap disabled, host rootfs directories may appear empty until you use the namespace tools. Snap\u2019s isolation is what causes the \u201cempty directory\u201d behavior you may\u2019ve encountered. ([discuss.linuxcontainers.org](https://discuss.linuxcontainers.org/t/rootfs-mount-locations-on-the-host-with-snap-lxd/2390?utm_source=openai))\n\n---\n\n## \u2705 What this means for you\n\nSince you\u2019re on Debian and not using Snap, here\u2019s how to know when you\u2019ll see container files:\n\n- Start a container (e.g. `lxc start `).\n- Once it\u2019s running, check the host filesystem under the storage-pool path (usually something like `/var/lib/lxd/storage-pools//containers//rootfs`) \u2014 you should find the files there. \n- If the container is stopped, that mount is unmounted, so looking there (without anything else) will show an empty directory or no visible file contents.\n\n---\n\nIf you like, I can look up the *exact* mount/unmount behavior for the version of LXD present in Debian 12 vs Debian 13 \u2014 that way you\u2019ll know what to expect when you upgrade (or not)." }, { "role": "user", "content": "if%20container%20is%20off%2C%20can%20I%20mount%20the%20zfs%20dataset%20for%20the%20container%20in%20%2Fmnt%3F%20how%3F" }, { "role": "assistant", "content": "Yes \u2014 you *can* manually mount a ZFS dataset belonging to a stopped LXD container to something like `/mnt/\u2026`. This lets you inspect files even when the container is off.\n\nHere\u2019s how to do it safely, assuming you\u2019ve installed LXD via APT (non-snap) on Debian 12 or 13, using ZFS as the storage backend.\n\n---\n\n## \u26a0\ufe0f Important Warnings Before You Begin\n\n- Mounting datasets manually is generally safe if the container is stopped. But avoid modifying files unless you\u2019re confident about permissions and UID/GID mappings \u2014 unprivileged containers map container UIDs to high host UIDs, meaning ownership/permissions might look weird or unsafe.\n- Avoid having the dataset mounted in multiple places (host path *and* as part of a container rootfs) at the same time \u2014 that can lead to data corruption or mount conflicts.\n- Always verify filesystem integrity (i.e., no active processes using it) before mounting to avoid \u201cdataset is busy\u201d errors. ([pieterbakker.com](https://pieterbakker.com/fix-dataset-is-busy-error-when-deleting-container-in-lxd/?utm_source=openai))\n\n---\n\n## \ud83d\udd27 Steps to Manually Mount a Stopped Container\u2019s ZFS Dataset\n\nLet\u2019s say your container is called `mycontainer` and your LXD storage pool is `lxdpool`.\n\n1. **Stop the container** \n ```bash\n sudo lxc stop mycontainer\n ```\n\n2. **Find the dataset name** \n Use `zfs list` to locate the dataset corresponding to that container rootfs. It will typically be something like: \n ```\n lxdpool/containers/mycontainer\n ```\n The `mountpoint` column might say `legacy` or show no mount. ([blog.karssen.org](https://blog.karssen.org/2023/03/11/lxd-container-snapshots-zfs-snapshots-and-moving-containers/?utm_source=openai))\n\n3. **Create a mount point** \n Make a directory under `/mnt` (or elsewhere) to mount to: \n ```bash\n sudo mkdir -p /mnt/mycontainer_rootfs\n ```\n\n4. **Mount it** \n Run:\n ```bash\n sudo zfs mount lxdpool/containers/mycontainer\n ```\n If the dataset uses a legacy or \"none\" mountpoint, you may need to specify the mountpoint in the mount command or set the dataset\u2019s `mountpoint` property first:\n\n ```bash\n sudo zfs set mountpoint=/mnt/mycontainer_rootfs lxdpool/containers/mycontainer\n sudo zfs mount lxdpool/containers/mycontainer\n ```\n\n Alternatively, if you don't want to change the dataset\u2019s mountpoint permanently, you can mount it manually via:\n\n ```bash\n sudo mount -t zfs lxdpool/containers/mycontainer /mnt/mycontainer_rootfs\n ```\n\n5. **Inspect files** \n You should now be able to `ls`, `cd`, read, and copy files from `/mnt/mycontainer_rootfs`. Just avoid writing unless you understand UID/GID mapping.\n\n6. **Unmount when done** \n ```bash\n sudo umount /mnt/mycontainer_rootfs\n # If you modified mountpoint property, you may want to restore it:\n sudo zfs set mountpoint=legacy lxdpool/containers/mycontainer\n ```\n\n---\n\n## \ud83d\udd04 What If You Run Into \u201cDataset is Busy\u201d or Mount Conflicts\n\n- If `zfs mount` fails with \u201cdataset is busy\u201d, it might have leftover mounts from previous container uses (especially LXD mount namespaces), or some process still has it open. You can use `lsof` or `fuser` to find what\u2019s holding it. ([pieterbakker.com](https://pieterbakker.com/fix-dataset-is-busy-error-when-deleting-container-in-lxd/?utm_source=openai)) \n- If so, kill/unmount those (may require use of `nsenter` if it\u2019s in a different namespace). Then try again. ([pieterbakker.com](https://pieterbakker.com/fix-dataset-is-busy-error-when-deleting-container-in-lxd/?utm_source=openai))\n\n---\n\nIf you want, I can tailor commands exactly for your LXD pool/dataset names so you can try mounting one of your containers." }, { "role": "user", "content": "is%20this%20same%20on%20debian%2013%3F" }, { "role": "assistant", "content": "Yes \u2014 Debian 13 behaves essentially the same in this regard. If you're using LXD with ZFS via Debian\u2019s native packaging (not Snap), the dataset for a container\u2019s root filesystem is only mounted when the container is running. When the container is stopped, that dataset is unmounted, so by default the rootfs won\u2019t be visible until the container is started (or you manually mount the dataset). This matches the behavior in Debian 12. \n\nIf you like, I can double-check any differences (if there are any subtle changes) between Debian 12 vs 13\u2019s LXD implementation to make sure your setup will behave exactly as expected." } ]