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* docs: pass boolean extra-vars as JSON for Ansible 12 compatibility Ansible 12 no longer accepts boolean values passed with -e var=true; the value is treated as a string, which breaks conditionals that expect a boolean. Update all documentation examples to use JSON syntax for boolean extra-vars and link to the Ansible 12 porting guide. Signed-off-by: Shashank Varma <324153016+shashankvarma499@users.noreply.github.com> * docs: clarify Ansible boolean types and configuration examples Signed-off-by: Kay Yan <kay.yan@daocloud.io> --------- Signed-off-by: Shashank Varma <324153016+shashankvarma499@users.noreply.github.com> Signed-off-by: Kay Yan <kay.yan@daocloud.io> Co-authored-by: Shashank Varma <324153016+shashankvarma499@users.noreply.github.com> Co-authored-by: Kay Yan <kay.yan@daocloud.io>
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Kata Containers
Kata Containers is a secure container runtime with lightweight virtual machines that supports multiple hypervisor solutions.
Hypervisors
Qemu is the only hypervisor supported by Kubespray.
Installation
To enable Kata Containers, set the following variables:
k8s-cluster.yml:
container_manager: containerd
kata_containers_enabled: true
etcd.yml:
etcd_deployment_type: host
Usage
By default, runc is used for pods. Kubespray generates the runtimeClass kata-qemu, and it is necessary to specify it as the runtimeClassName of a pod spec to use Kata Containers:
$ kubectl get runtimeclass
NAME HANDLER AGE
kata-qemu kata-qemu 3m34s
$
$ cat nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: mypod
spec:
runtimeClassName: kata-qemu
containers:
- name: nginx
image: nginx:1.14.2
$
$ kubectl apply -f nginx.yaml
Configuration
Recommended : Pod Overhead
Pod Overhead is a feature for accounting for the resources consumed by the Runtime Class used by the Pod.
When this feature is enabled, Kubernetes will count the fixed amount of CPU and memory set in the configuration as used by the virtual machine and not by the containers running in the Pod.
Pod Overhead is mandatory if you run Pods with Kata Containers that use resources limits.
Set cgroup driver:
To enable Pod Overhead feature you have to configure Kubelet with the appropriate cgroup driver, using the following configuration:
cgroupfs works best:
kubelet_cgroup_driver: cgroupfs
... but when using cgroups v2 (see https://www.redhat.com/en/blog/world-domination-cgroups-rhel-8-welcome-cgroups-v2) you can use systemd as well:
kubelet_cgroup_driver: systemd
Qemu hypervisor configuration:
The configuration for the Qemu hypervisor uses the following values:
kata_containers_qemu_overhead: true
kata_containers_qemu_overhead_fixed_cpu: 10m
kata_containers_qemu_overhead_fixed_memory: 290Mi
Optional : Select Kata Containers version
Optionally you can select the Kata Containers release version to be installed. The available releases are published in GitHub.
kata_containers_version: 2.2.2
Optional : Debug
Debug is disabled by default for all the components of Kata Containers. You can change this behaviour with the following configuration:
kata_containers_qemu_debug: 'true'