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Add kube-dns/CoreDNS documentation
This commit is contained in:
Sebastiaan van Steenis
committed by
Denise Schannon
Denise Schannon
parent
13d88761d5
commit
0b80d6a698
@@ -162,3 +162,14 @@ pod "kube-dns-5fd74c7488-6pwsf" deleted
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```
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Try to resolve name again using [Check if domain names are resolving](#check-if-domain-names-are-resolving).
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If you want to check the kube-dns configuration in your cluster (for example, to check if there are different upstream nameservers configured), you can run the following command to list the kube-dns configuration:
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```
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kubectl -n kube-system get configmap kube-dns -o go-template='{{range $key, $value := .data}}{{ $key }}{{":"}}{{ $value }}{{"\n"}}{{end}}'
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```
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Example output:
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```
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upstreamNameservers:["1.1.1.1"]
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```
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@@ -7,7 +7,7 @@ RKE supports pluggable add-ons. Add-ons are used to deploy several cluster compo
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* [Network plug-ins]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/network-plugins/)
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* [Ingress controller]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/ingress-controllers/)
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* KubeDNS
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* [DNS provider]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/dns/)
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The images used for these add-ons under the [`system_images` directive]({{< baseurl >}}/rke/v0.1.x/en/config-options/system-images/). For each Kubernetes version, there are default images associated with each add-on, but these can be overridden by changing the image tag in `system_images`.
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@@ -0,0 +1,64 @@
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---
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title: DNS provider
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weight: 262
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---
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By default, RKE deploys [kube-dns](https://github.com/kubernetes/dns) as DNS provider for your cluster.
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RKE will deploy kube-dns as a Deployment with the default replica count of 1. The pod consists of 3 containers: `kubedns`, `dnsmasq` and `sidecar`. RKE will also deploy kube-dns-autoscaler as a Deployment, which will scale the kube-dns Deployment by using the number of cores and nodes. Please see [Linear Mode](https://github.com/kubernetes-incubator/cluster-proportional-autoscaler#linear-mode) for more information about this logic.
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The images used for kube-dns are under the [`system_images` directive]({{< baseurl >}}/rke/v0.1.x/en/config-options/system-images/). For each Kubernetes version, there are default images associated with kube-dns, but these can be overridden by changing the image tag in `system_images`.
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## Scheduling kube-dns
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If you only wanted ingress controllers to be deployed on specific nodes, you can set a `node_selector` for the ingress. The label in the `node_selector` would need to match the label on the nodes for the ingress controller to be deployed.
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```yaml
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nodes:
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- address: 1.1.1.1
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role: [controlplane,worker,etcd]
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user: root
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labels:
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app: dns
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dns:
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provider: kube-dns
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node_selector:
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app: dns
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```
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## Disabling kube-dns
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You can disable the default DNS provider by specifying `none` to the dns `provider` directive in the cluster configuration. Be aware that this will prevent your pods from doing name resolution in your cluster.
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```yaml
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dns:
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provider: none
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```
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## Configuring kube-dns
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### Upstream nameservers
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By default, kube-dns will use the host configured nameservers (usually residing at `/etc/resolv.conf`) to resolve external queries. If you want to configure specific upstream nameservers to be used by kube-dns, you can use the `upstreamnameservers` directive.
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```yaml
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dns:
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provider: kube-dns
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upstreamnameservers:
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- 1.1.1.1
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- 8.8.4.4
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```
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## CoreDNS (experimental)
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<p>Experimental support for CoreDNS is available in RKE v0.2.0 and later.</p>
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If you want to use CoreDNS, you can set the `provider` directive to `coredns`. Both the `node_selector` and `upstreamnameservers` directive is also supported for CoreDNS.
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```yaml
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dns:
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provider: coredns
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upstreamnameservers:
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- 1.1.1.1
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- 8.8.4.4
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```
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@@ -6,7 +6,7 @@ When RKE is deploying Kubernetes, there are several images that are pulled. Thes
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As of `v0.1.6`, the functionality of a couple of the system images were consolidated into a single `rancher/rke-tools` image to simplify and speed the deployment process.
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You can configure the [network plug-ins]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/network-plugins/) and [ingress controller]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/ingress-controllers/) as well as the options for these add-ons separately.
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You can configure the [network plug-ins]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/network-plugins/), [ingress controller]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/ingress-controllers/) and [dns provider]({{< baseurl >}}/rke/v0.1.x/en/config-options/add-ons/dns/) as well as the options for these add-ons separately.
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This is the example of the full list of system images used to deploy Kubernetes through RKE. The image tags are dependent on the [Kubernetes image/version used](https://github.com/rancher/types/blob/master/apis/management.cattle.io/v3/k8s_defaults.go).
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@@ -14,39 +14,49 @@ This is the example of the full list of system images used to deploy Kubernetes
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```yaml
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system_images:
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kubernetes: rancher/hyperkube:v1.10.3-rancher2
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etcd: rancher/coreos-etcd:v3.1.12
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alpine: rancher/rke-tools:v0.1.9
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nginx_proxy: rancher/rke-tools:v0.1.9
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cert_downloader: rancher/rke-tools:v0.1.9
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kubernetes_services_sidecar: rancher/rke-tools:v0.1.9
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kubedns: rancher/k8s-dns-kube-dns-amd64:1.14.8
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dnsmasq: rancher/k8s-dns-dnsmasq-nanny-amd64:1.14.8
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kubedns_sidecar: rancher/k8s-dns-sidecar-amd64:1.14.8
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kubedns_autoscaler: rancher/cluster-proportional-autoscaler-amd64:1.0.0
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pod_infra_container: rancher/pause-amd64:3.1
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etcd: rancher/coreos-etcd:v3.2.24
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alpine: rancher/rke-tools:v0.1.24
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nginx_proxy: rancher/rke-tools:v0.1.24
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cert_downloader: rancher/rke-tools:v0.1.24
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kubernetes: rancher/hyperkube:v1.13.1-rancher1
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kubernetes_services_sidecar: rancher/rke-tools:v0.1.24
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pod_infra_container: rancher/pause-amd64:3.1
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# Flannel Networking Options
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flannel: rancher/coreos-flannel:v0.9.1
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flannel_cni: rancher/coreos-flannel-cni:v0.2.0
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# kube-dns images
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kubedns: rancher/k8s-dns-kube-dns-amd64:1.15.0
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dnsmasq: rancher/k8s-dns-dnsmasq-nanny-amd64:1.15.0
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kubedns_sidecar: rancher/k8s-dns-sidecar-amd64:1.15.0
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kubedns_autoscaler: rancher/cluster-proportional-autoscaler-amd64:1.0.0
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# Calico Networking Options
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calico_node: rancher/calico-node:v3.1.1
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calico_cni: rancher/calico-cni:v3.1.1
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calico_ctl: rancher/calico-ctl:v2.0.0
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# CoreDNS images
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coredns: coredns/coredns:1.2.6
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coredns_autoscaler: rancher/cluster-proportional-autoscaler-amd64:1.0.0
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# Canal Networking Options
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canal_node: rancher/calico-node:v3.1.1
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canal_cni: rancher/calico-cni:v3.1.1
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canal_flannel: rancher/coreos-flannel:v0.9.1
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# Flannel images
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flannel: rancher/coreos-flannel:v0.10.0
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flannel_cni: rancher/coreos-flannel-cni:v0.3.0
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# Weave Networking Options
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weave_node: weaveworks/weave-kube:2.1.2
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weave_cni: weaveworks/weave-npc:2.1.2
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# Calico images
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calico_node: rancher/calico-node:v3.4.0
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calico_cni: rancher/calico-cni:v3.4.0
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calico_controllers: ""
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calico_ctl: rancher/calico-ctl:v2.0.0
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# Ingress Options
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ingress: rancher/nginx-ingress-controller:0.10.2-rancher3
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ingress_backend: rancher/nginx-ingress-controller-defaultbackend:1.4
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# Canal images
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canal_node: rancher/calico-node:v3.4.0
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canal_cni: rancher/calico-cni:v3.4.0
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canal_flannel: rancher/coreos-flannel:v0.10.0
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# Weave images
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weave_node: weaveworks/weave-kube:2.5.0
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weave_cni: weaveworks/weave-npc:2.5.0
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# Ingress controller images
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ingress: rancher/nginx-ingress-controller:0.21.0-rancher1
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ingress_backend: rancher/nginx-ingress-controller-defaultbackend:1.4
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# Metrics server image
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metrics_server: rancher/metrics-server-amd64:v0.3.1
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```
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Prior to `v0.1.6`, instead of using the `rancher/rke-tools` image, we used the following images:
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