c0d2cca45d
- Exclude kubelet CPU/RAM (kube-reserved) from cgroup. It decreases a chance of overcommitment - Add a possibility to modify Kubelet node-status-update-frequency - Add a posibility to configure node-monitor-grace-period, node-monitor-period, pod-eviction-timeout for Kubernetes controller manager - Add Kubernetes Relaibility Documentation with recomendations for various scenarios. Signed-off-by: Sergii Golovatiuk <sgolovatiuk@mirantis.com>
48 lines
2.2 KiB
Markdown
48 lines
2.2 KiB
Markdown
Large deployments of K8s
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For a large scaled deployments, consider the following configuration changes:
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* Tune [ansible settings]
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(http://docs.ansible.com/ansible/intro_configuration.html)
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for `forks` and `timeout` vars to fit large numbers of nodes being deployed.
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* Override containers' `foo_image_repo` vars to point to intranet registry.
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* Override the ``download_run_once: true`` and/or ``download_localhost: true``.
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See download modes for details.
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* Adjust the `retry_stagger` global var as appropriate. It should provide sane
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load on a delegate (the first K8s master node) then retrying failed
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push or download operations.
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* Tune parameters for DNS related applications (dnsmasq daemon set, kubedns
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replication controller). Those are ``dns_replicas``, ``dns_cpu_limit``,
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``dns_cpu_requests``, ``dns_memory_limit``, ``dns_memory_requests``.
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Please note that limits must always be greater than or equal to requests.
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* Tune CPU/memory limits and requests. Those are located in roles' defaults
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and named like ``foo_memory_limit``, ``foo_memory_requests`` and
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``foo_cpu_limit``, ``foo_cpu_requests``. Note that 'Mi' memory units for K8s
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will be submitted as 'M', if applied for ``docker run``, and cpu K8s units
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will end up with the 'm' skipped for docker as well. This is required as
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docker does not understand k8s units well.
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* Tune ``kubelet_status_update_frequency`` to increase reliability of kubelet.
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``kube_controller_node_monitor_grace_period``,
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``kube_controller_node_monitor_period``,
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``kube_controller_pod_eviction_timeout`` for better Kubernetes reliability.
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Check out [Kubernetes Reliability](kubernetes-reliability.md)
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* Add calico-rr nodes if you are deploying with Calico or Canal. Nodes recover
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from host/network interruption much quicker with calico-rr. Note that
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calico-rr role must be on a host without kube-master or kube-node role (but
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etcd role is okay).
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* Check out the
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[Inventory](getting-started.md#building-your-own-inventory)
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section of the Getting started guide for tips on creating a large scale
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Ansible inventory.
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For example, when deploying 200 nodes, you may want to run ansible with
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``--forks=50``, ``--timeout=600`` and define the ``retry_stagger: 60``.
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