Merge pull request #6778 from AkihiroSuda/docs-cri-simplify
Add `docs/snapshotters`; simplify `docs/cri`
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Kazuyoshi Kato
GitHub
commit
f033f6ff85
@ -6,7 +6,104 @@ path: `/etc/containerd/config.toml`).
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See [here](https://github.com/containerd/containerd/blob/main/docs/ops.md)
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for more information about containerd config.
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Note that the `[plugins."io.containerd.grpc.v1.cri"]` section is specific to CRI,
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and not recognized by other containerd clients such as `ctr`, `nerdctl`, and Docker/Moby.
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## Basic configuration
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### Cgroup Driver
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While containerd and Kubernetes use the legacy `cgroupfs` driver for managing cgroups by default,
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it is recommended to use the `systemd` driver on systemd-based hosts for compliance of
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[the "single-writer" rule](https://systemd.io/CGROUP_DELEGATION/) of cgroups.
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To configure containerd to use the `systemd` driver, set the following option in `/etc/containerd/config.toml`:
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```toml
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version = 2
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
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SystemdCgroup = true
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```
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In addition to containerd, you have to configure the `KubeletConfiguration` to use the "systemd" cgroup driver.
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The `KubeletConfiguration` is typically located at `/var/lib/kubelet/config.yaml`:
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```yaml
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kind: KubeletConfiguration
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apiVersion: kubelet.config.k8s.io/v1beta1
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cgroupDriver: "systemd"
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```
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kubeadm users should also see [the kubeadm documentation](https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/configure-cgroup-driver/).
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### Snapshotter
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The default snapshotter is set to `overlayfs` (akin to Docker's `overlay2` storage driver):
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```toml
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version = 2
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[plugins."io.containerd.grpc.v1.cri".containerd]
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snapshotter = "overlayfs"
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```
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See [here](https://github.com/containerd/containerd/blob/main/docs/snapshotters) for other supported snapshotters.
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### Runtime classes
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The following example registers custom runtimes into containerd:
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```toml
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version = 2
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[plugins."io.containerd.grpc.v1.cri".containerd]
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default_runtime_name = "crun"
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
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# crun: https://github.com/containers/crun
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.crun]
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runtime_type = "io.containerd.runc.v2"
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.crun.options]
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BinaryName = "/usr/local/bin/crun"
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# gVisor: https://gvisor.dev/
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.gvisor]
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runtime_type = "io.containerd.runsc.v1"
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# Kata Containers: https://katacontainers.io/
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[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.kata]
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runtime_type = "io.containerd.kata.v2"
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```
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In addition, you have to install the following `RuntimeClass` resources into the cluster
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with the `cluster-admin` role:
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```yaml
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apiVersion: node.k8s.io/v1
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kind: RuntimeClass
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metadata:
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name: crun
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handler: crun
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---
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apiVersion: node.k8s.io/v1
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kind: RuntimeClass
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metadata:
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name: gvisor
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handler: gvisor
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---
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apiVersion: node.k8s.io/v1
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kind: RuntimeClass
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metadata:
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name: kata
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handler: kata
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```
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To apply a runtime class to a pod, set `.spec.runtimeClassName`:
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```yaml
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apiVersion: v1
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kind: Pod
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spec:
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runtimeClassName: crun
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```
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See also [the Kubernetes documentation](https://kubernetes.io/docs/concepts/containers/runtime-class/).
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## Full configuration
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The explanation and default value of each configuration item are as follows:
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<details>
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<p>
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```toml
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# Use config version 2 to enable new configuration fields.
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# Config file is parsed as version 1 by default.
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@ -324,6 +421,9 @@ version = 2
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config_path = ""
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```
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</p>
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</details>
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## Registry Configuration
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Here is a simple example for a default registry hosts configuration. Set
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@ -344,6 +444,18 @@ server = "https://docker.io"
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capabilities = ["pull", "resolve"]
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```
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To specify a custom certificate:
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```
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$ cat /etc/containerd/certs.d/192.168.12.34:5000/hosts.toml
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server = "https://192.168.12.34:5000"
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[host."https://192.168.12.34:5000"]
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ca = "/path/to/ca.crt"
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```
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See [`docs/hosts.md`](https://github.com/containerd/containerd/blob/main/docs/hosts.md) for the further information.
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## Untrusted Workload
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The recommended way to run untrusted workload is to use
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@ -10,6 +10,13 @@ should now use the form
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config_path = "/etc/containerd/certs.d"
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```
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- - -
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<!-- TODO: remove in containerd 2.0 -->
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<details>
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<summary>Show the original content (<strong>DEPRECATED</strong>)</summary>
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<p>
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## Configure Registry Endpoint
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With containerd, `docker.io` is the default image registry. You can also set up other image registries similar to docker.
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@ -193,3 +200,6 @@ Image is up to date for sha256:78096d0a54788961ca68393e5f8038704b97d8af374249dc5
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---
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NOTE: The configuration syntax used in this doc is in version 2 which is the recommended since `containerd` 1.3. For the previous config format you can reference [https://github.com/containerd/cri/blob/release/1.2/docs/registry.md](https://github.com/containerd/cri/blob/release/1.2/docs/registry.md).
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</p>
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</details>
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26
docs/snapshotters/README.md
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26
docs/snapshotters/README.md
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# Snapshotters
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Snapshotters manage the snapshots of the container filesystems.
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The available snapshotters can be inspected by running `ctr plugins ls` or `nerdctl info`.
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## Core snapshotter plugins
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Generic:
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- `overlayfs` (default): OverlayFS. This driver is akin to Docker/Moby's "overlay2" storage driver, but containerd's implementation is not called "overlay2".
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- `native`: Native file copying driver. Akin to Docker/Moby's "vfs" driver.
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Filesystem-specific:
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- `btrfs`: btrfs. Needs the plugin root (`/var/lib/containerd/io.containerd.snapshotter.v1.btrfs`) to be mounted as btrfs.
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- `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 .
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- `devmapper`: ext4/xfs device mapper. See [`devmapper.md`](./devmapper.md).
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[Deprecated](https://github.com/containerd/containerd/blob/main/RELEASES.md#deprecated-features):
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- `aufs`: AUFS. Deprecated since containerd 1.5. Planned to be removed in containerd 2.0. See also https://github.com/containerd/aufs .
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## Non-core snapshotter plugins
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- `fuse-overlayfs`: [FUSE-OverlayFS Snapshotter](https://github.com/containerd/fuse-overlayfs-snapshotter)
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- `nydus`: [Nydus Snapshotter](https://github.com/containerd/nydus-snapshotter)
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- `overlaybd`: [OverlayBD Snapshotter](https://github.com/containerd/accelerated-container-image)
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- `stargz`: [Stargz Snapshotter](https://github.com/containerd/stargz-snapshotter)
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