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34 lines
1.5 KiB
Markdown
34 lines
1.5 KiB
Markdown
# Kubernetes
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CoreDNS can run in place of the standard Kube-DNS in Kubernetes. Using the *kubernetes*
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plugin, CoreDNS will read zone data from a Kubernetes cluster. It implements the
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spec defined for Kubernetes DNS-Based service discovery:
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https://github.com/kubernetes/dns/blob/master/docs/specification.md
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## deploy.sh and coredns.yaml.sed
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`deploy.sh` is a convenience script to generate a manifest for running CoreDNS on a cluster
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that is currently running standard kube-dns. Using the `coredns.yaml.sed` file as a template,
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it creates a ConfigMap and a CoreDNS deployment, then updates the Kube-DNS service selector
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to use the CoreDNS deployment. By re-using the existing service, there is no disruption in
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servicing requests.
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The script doesn't delete the kube-dns deployment or replication controller - you'll have to
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do that manually, after deploying CoreDNS.
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You should examine the manifest carefully and make sure it is correct for your particular
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cluster. Depending on how you have built your cluster and the version you are running,
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some modifications to the manifest may be needed.
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In the best case scenario, all that's needed to replace Kube-DNS are these two commands:
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~~~
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$ ./deploy.sh | kubectl apply -f -
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$ kubectl delete --namespace=kube-system deployment kube-dns
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~~~
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For non-RBAC deployments, you'll need to edit the resulting yaml before applying it:
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1. Remove the line `serviceAccountName: coredns` from the `Deployment` section.
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2. Remove the `ServiceAccount`, `ClusterRole`, and `ClusterRoleBinding` sections.
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