73 lines
2.4 KiB
Markdown
73 lines
2.4 KiB
Markdown
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# cgroups
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To avoid the rivals for resources between containers or the impact on the host in Kubernetes, the kubelet components will rely on cgroups to limit the container’s resources usage.
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## Enforcing Node Allocatable
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You can use `kubelet_enforce_node_allocatable` to set node allocatable enforcement.
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```yaml
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# A comma separated list of levels of node allocatable enforcement to be enforced by kubelet.
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kubelet_enforce_node_allocatable: "pods"
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# kubelet_enforce_node_allocatable: "pods,kube-reserved"
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# kubelet_enforce_node_allocatable: "pods,kube-reserved,system-reserved"
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```
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Note that to enforce kube-reserved or system-reserved, `kube_reserved_cgroups` or `system_reserved_cgroups` needs to be specified respectively.
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Here is an example:
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```yaml
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kubelet_enforce_node_allocatable: "pods,kube-reserved,system-reserved"
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# Reserve this space for kube resources
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# Set to true to reserve resources for kube daemons
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kube_reserved: true
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kube_reserved_cgroups_for_service_slice: kube.slice
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kube_reserved_cgroups: "/{{ kube_reserved_cgroups_for_service_slice }}"
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kube_memory_reserved: 256Mi
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kube_cpu_reserved: 100m
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# kube_ephemeral_storage_reserved: 2Gi
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# kube_pid_reserved: "1000"
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# Reservation for master hosts
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kube_master_memory_reserved: 512Mi
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kube_master_cpu_reserved: 200m
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# kube_master_ephemeral_storage_reserved: 2Gi
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# kube_master_pid_reserved: "1000"
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# Set to true to reserve resources for system daemons
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system_reserved: true
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system_reserved_cgroups_for_service_slice: system.slice
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system_reserved_cgroups: "/{{ system_reserved_cgroups_for_service_slice }}"
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system_memory_reserved: 512Mi
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system_cpu_reserved: 500m
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# system_ephemeral_storage_reserved: 2Gi
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# system_pid_reserved: "1000"
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# Reservation for master hosts
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system_master_memory_reserved: 256Mi
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system_master_cpu_reserved: 250m
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# system_master_ephemeral_storage_reserved: 2Gi
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# system_master_pid_reserved: "1000"
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```
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After the setup, the cgroups hierarchy is as follows:
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```bash
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/ (Cgroups Root)
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├── kubepods.slice
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│ ├── ...
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│ ├── kubepods-besteffort.slice
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│ ├── kubepods-burstable.slice
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│ └── ...
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├── kube.slice
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│ ├── ...
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│ ├── {{container_manager}}.service
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│ ├── kubelet.service
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│ └── ...
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├── system.slice
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│ └── ...
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└── ...
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```
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You can learn more in the [official kubernetes documentation](https://kubernetes.io/docs/tasks/administer-cluster/reserve-compute-resources/).
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