52 lines
2.4 KiB
Markdown
52 lines
2.4 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](https://docs.ansible.com/ansible/latest/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 control plane node) then retrying failed
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push or download operations.
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* Tune parameters for DNS related applications
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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_apiserver_pod_eviction_not_ready_timeout_seconds`` &
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``kube_apiserver_pod_eviction_unreachable_timeout_seconds`` for better Kubernetes reliability.
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Check out [Kubernetes Reliability](/docs/kubernetes-reliability.md)
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* Tune network prefix sizes. Those are ``kube_network_node_prefix``,
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``kube_service_addresses`` and ``kube_pods_subnet``.
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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.
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* Check out the
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[Inventory](/docs/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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* Override the ``etcd_events_cluster_setup: true`` store events in a separate
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dedicated etcd instance.
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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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