417a931f78
When download_run_once with download_localhost is used, docker is expected to be running on the delegate localhost. That may be not the case for a non localhost delegate, which is the kube-master otherwise. Then the dnsmasq role, had it been invoked early before deployment starts, would fail because of the missing docker dependency. * Fix that dependency on docker and do not pre download dnsmasq image for the dnsmasq role, if download_localhost is disabled. * Remove become: false for docker CLI invocation because that's not the common pattern to allow users access docker CLI w/o sudo. * Fix opt bin path hack for localhost delegate to ignore errors when it fails with "sudo password required" otherwise. * Describe download_run_once with download_localhost use case in docs as well. Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
25 lines
1.3 KiB
Markdown
25 lines
1.3 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](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`` to download container images only once
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then push to cluster nodes in batches. The default delegate node
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for pushing images is the first kube-master. Note, if you have passwordless sudo
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and docker enabled on the separate admin node, you may want to define the
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``download_localhost: true``, which makes that node a delegate for pushing images
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while running the deployment with ansible. This maybe the case if cluster nodes
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cannot access each over via ssh or you want to use local docker images as a cache
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for multiple clusters.
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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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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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