103 lines
3.2 KiB
Markdown
103 lines
3.2 KiB
Markdown
# containerd
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[containerd] An industry-standard container runtime with an emphasis on simplicity, robustness and portability
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Kubespray supports basic functionality for using containerd as the default container runtime in a cluster.
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_To use the containerd container runtime set the following variables:_
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## k8s_cluster.yml
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When kube_node contains etcd, you define your etcd cluster to be as well schedulable for Kubernetes workloads. Thus containerd and dockerd can not run at same time, must be set to bellow for running etcd cluster with only containerd.
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```yaml
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container_manager: containerd
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```
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## etcd.yml
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```yaml
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etcd_deployment_type: host
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```
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## Containerd config
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Example: define registry mirror for docker hub
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```yaml
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containerd_registries:
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"docker.io":
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- "https://mirror.gcr.io"
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- "https://registry-1.docker.io"
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```
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`containerd_registries` is ignored for pulling images when `image_command_tool=nerdctl`
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(the default for `container_manager=containerd`). Use `crictl` instead, it supports
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`containerd_registries` but lacks proper multi-arch support (see
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[#8375](https://github.com/kubernetes-sigs/kubespray/issues/8375)):
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```yaml
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image_command_tool: crictl
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```
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### Containerd Runtimes
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Containerd supports multiple runtime configurations that can be used with
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[RuntimeClass] Kubernetes feature. See [runtime classes in containerd] for the
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details of containerd configuration.
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In kubespray, the default runtime name is "runc", and it can be configured with the `containerd_runc_runtime` dictionary:
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```yaml
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containerd_runc_runtime:
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name: runc
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type: "io.containerd.runc.v2"
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engine: ""
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root: ""
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options:
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systemdCgroup: "false"
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binaryName: /usr/local/bin/my-runc
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base_runtime_spec: cri-base.json
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```
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Further runtimes can be configured with `containerd_additional_runtimes`, which
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is a list of such dictionaries.
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Default runtime can be changed by setting `containerd_default_runtime`.
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#### base_runtime_spec
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`base_runtime_spec` key in a runtime dictionary can be used to explicitly
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specify a runtime spec json file. We ship the default one which is generated
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with `ctr oci spec > /etc/containerd/cri-base.json`. It will be used if you set
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`base_runtime_spec: cri-base.json`. The main advantage of doing so is the presence of
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`rlimits` section in this configuration, which will restrict the maximum number
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of file descriptors(open files) per container to 1024.
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You can tune many more [settings][runtime-spec] by supplying your own file name and content with `containerd_base_runtime_specs`:
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```yaml
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containerd_base_runtime_specs:
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cri-spec-custom.json: |
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{
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"ociVersion": "1.0.2-dev",
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"process": {
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"user": {
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"uid": 0,
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...
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```
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The files in this dict will be placed in containerd config directory,
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`/etc/containerd` by default. The files can then be referenced by filename in a
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runtime:
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```yaml
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containerd_runc_runtime:
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name: runc
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base_runtime_spec: cri-spec-custom.json
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...
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```
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[containerd]: https://containerd.io/
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[RuntimeClass]: https://kubernetes.io/docs/concepts/containers/runtime-class/
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[runtime classes in containerd]: https://github.com/containerd/containerd/blob/main/docs/cri/config.md#runtime-classes
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[runtime-spec]: https://github.com/opencontainers/runtime-spec
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