64 lines
2.5 KiB
Markdown
64 lines
2.5 KiB
Markdown
# Snapshotters
|
|
|
|
Snapshotters manage the snapshots of the container filesystems.
|
|
|
|
The available snapshotters can be inspected by running `ctr plugins ls` or `nerdctl info`.
|
|
|
|
## Core snapshotter plugins
|
|
|
|
Generic:
|
|
- `overlayfs` (default): OverlayFS. This driver is akin to Docker/Moby's "overlay2" storage driver, but containerd's implementation is not called "overlay2".
|
|
- `native`: Native file copying driver. Akin to Docker/Moby's "vfs" driver.
|
|
|
|
Block-based:
|
|
- `blockfile`: A driver using raw block files for each snapshot. Block files are copied from a parent or base empty block file. Mounting requires a virtual machine or support for loopback mounts.
|
|
- `devmapper`: ext4/xfs device mapper. See [`devmapper.md`](./devmapper.md).
|
|
|
|
Filesystem-specific:
|
|
- `btrfs`: btrfs. Needs the plugin root (`/var/lib/containerd/io.containerd.snapshotter.v1.btrfs`) to be mounted as btrfs.
|
|
- `zfs`: ZFS. Needs the plugin root (`/var/lib/containerd/io.containerd.snapshotter.v1.zfs`) to be mounted as ZFS. See also https://github.com/containerd/zfs .
|
|
|
|
[Deprecated](https://github.com/containerd/containerd/blob/main/RELEASES.md#deprecated-features):
|
|
- `aufs`: AUFS. Deprecated since containerd 1.5. Removed in containerd 2.0. See also https://github.com/containerd/aufs .
|
|
|
|
## Non-core snapshotter plugins
|
|
|
|
- `fuse-overlayfs`: [FUSE-OverlayFS Snapshotter](https://github.com/containerd/fuse-overlayfs-snapshotter)
|
|
- `nydus`: [Nydus Snapshotter](https://github.com/containerd/nydus-snapshotter)
|
|
- `overlaybd`: [OverlayBD Snapshotter](https://github.com/containerd/accelerated-container-image)
|
|
- `stargz`: [Stargz Snapshotter](https://github.com/containerd/stargz-snapshotter)
|
|
|
|
## Mount target
|
|
|
|
Mounts can optionally specify a target to describe submounts in the container's
|
|
rootfs. For example, if the snapshotter wishes to bind mount to a subdirectory
|
|
ontop of an overlayfs mount, they can return the following mounts:
|
|
|
|
```json
|
|
[
|
|
{
|
|
"type": "overlay",
|
|
"source": "overlay",
|
|
"options": [
|
|
"workdir=...",
|
|
"upperdir=...",
|
|
"lowerdir=..."
|
|
]
|
|
},
|
|
{
|
|
"type": "bind",
|
|
"source": "/path/on/host",
|
|
"target": "/path/inside/container",
|
|
"options": [
|
|
"ro",
|
|
"rbind"
|
|
]
|
|
}
|
|
]
|
|
```
|
|
|
|
However, the mountpoint `/path/inside/container` needs to exist for the bind
|
|
mount, so one of the previous mounts must be responsible for providing that
|
|
directory in the rootfs. In this case, one of the lower dirs of the overlay has
|
|
that directory to enable the bind mount.
|