84 lines
2.2 KiB
Markdown
84 lines
2.2 KiB
Markdown
# CRI-O
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[CRI-O] is a lightweight container runtime for Kubernetes.
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Kubespray supports basic functionality for using CRI-O as the default container runtime in a cluster.
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* Kubernetes supports CRI-O on v1.11.1 or later.
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* etcd: configure either kubeadm managed etcd or host deployment
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_To use the CRI-O container runtime set the following variables:_
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## all/all.yml
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```yaml
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download_container: false
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skip_downloads: false
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etcd_kubeadm_enabled: true
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```
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## k8s_cluster/k8s_cluster.yml
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```yaml
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container_manager: crio
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```
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## etcd.yml
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```yaml
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etcd_deployment_type: host # optionally and mutually exclusive with etcd_kubeadm_enabled
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```
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## all/crio.yml
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Enable docker hub registry mirrors
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```yaml
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crio_registries:
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- prefix: docker.io
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insecure: false
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blocked: false
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location: registry-1.docker.io
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unqualified: false
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mirrors:
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- location: 192.168.100.100:5000
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insecure: true
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- location: mirror.gcr.io
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insecure: false
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```
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## Note about pids_limit
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For heavily mult-threaded workloads like databases, the default of 1024 for pids-limit is too low.
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This parameter controls not just the number of processes but also the amount of threads
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(since a thread is technically a process with shared memory). See [cri-o#1921]
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In order to increase the default `pids_limit` for cri-o based deployments you need to set the `crio_pids_limit`
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for your `k8s_cluster` ansible group or per node depending on the use case.
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```yaml
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crio_pids_limit: 4096
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```
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[CRI-O]: https://cri-o.io/
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[cri-o#1921]: https://github.com/cri-o/cri-o/issues/1921
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## Note about user namespaces
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CRI-O has support for user namespaces. This feature is optional and can be enabled by setting the following two variables.
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```yaml
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crio_runtimes:
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- name: runc
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path: /usr/bin/runc
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type: oci
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root: /run/runc
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allowed_annotations:
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- "io.kubernetes.cri-o.userns-mode"
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crio_remap_enable: true
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```
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The `allowed_annotations` configures `crio.conf` accordingly.
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The `crio_remap_enable` configures the `/etc/subuid` and `/etc/subgid` files to add an entry for the **containers** user.
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By default, 16M uids and gids are reserved for user namespaces (256 pods * 65536 uids/gids) at the end of the uid/gid space.
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