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by setting a default runtime spec with a patch for RLIMIT_NOFILE. - Introduces containerd_base_runtime_spec_rlimit_nofile. - Generates base_runtime_spec on-the-fly, to use the containerd version of the node.
107 lines
3.3 KiB
Markdown
107 lines
3.3 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 specs and limiting number of open files
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`base_runtime_spec` key in a runtime dictionary is used to explicitly
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specify a runtime spec json file. `runc` runtime has it set to `cri-base.json`,
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which is generated with `ctr oci spec > /etc/containerd/cri-base.json` and
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updated to include a custom setting for maximum number of file descriptors per
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container.
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You can change maximum number of file descriptors per container for the default
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`runc` runtime by setting the `containerd_base_runtime_spec_rlimit_nofile`
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variable.
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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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