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Update content on kube-dns to coredns configmap translation #13781

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Update content on kube-dns to coredns configmap translation #13781

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afd6824
Update content on kube-dns to coredns configmap translation
rajansandeep Apr 11, 2019
351414d
better wording
chrisohaver Apr 11, 2019
99e36e0
Small wording change
rajansandeep Apr 11, 2019
556b77d
Remove `upstream`
rajansandeep Apr 11, 2019
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37 changes: 18 additions & 19 deletions content/en/docs/tasks/administer-cluster/dns-custom-nameservers.md
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Original file line number Diff line number Diff line change
Expand Up @@ -82,7 +82,7 @@ data:
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
forward . /etc/resolv.conf
cache 30
loop
reload
Expand All @@ -100,7 +100,7 @@ The Corefile configuration includes the following [plugins](https://coredns.io/p
> `Upstream` is used for resolving services that point to external hosts (External Services).

* [prometheus](https://coredns.io/plugins/prometheus/): Metrics of CoreDNS are available at http://localhost:9153/metrics in [Prometheus](https://prometheus.io/) format.
* [proxy](https://coredns.io/plugins/proxy/): Any queries that are not within the cluster domain of Kubernetes will be forwarded to predefined resolvers (/etc/resolv.conf).
* [forward](https://coredns.io/plugins/forward/): Any queries that are not within the cluster domain of Kubernetes will be forwarded to predefined resolvers (/etc/resolv.conf).
* [cache](https://coredns.io/plugins/cache/): This enables a frontend cache.
* [loop](https://coredns.io/plugins/loop/): Detects simple forwarding loops and halts the CoreDNS process if a loop is found.
* [reload](https://coredns.io/plugins/reload): Allows automatic reload of a changed Corefile. After you edit the ConfigMap configuration, allow two minutes for your changes to take effect.
Expand All @@ -110,7 +110,7 @@ You can modify the default CoreDNS behavior by modifying the ConfigMap.

### Configuration of Stub-domain and upstream nameserver using CoreDNS

CoreDNS has the ability to configure stubdomains and upstream nameservers using the [proxy plugin](https://coredns.io/plugins/proxy/).
CoreDNS has the ability to configure stubdomains and upstream nameservers using the [forward plugin](https://coredns.io/plugins/forward/).

#### Example
If a cluster operator has a [Consul](https://www.consul.io/) domain server located at 10.150.0.1, and all Consul names have the suffix .consul.local. To configure it in CoreDNS, the cluster administrator creates the following stanza in the CoreDNS ConfigMap.
Expand All @@ -119,18 +119,15 @@ If a cluster operator has a [Consul](https://www.consul.io/) domain server locat
consul.local:53 {
errors
cache 30
proxy . 10.150.0.1
forward . 10.150.0.1
}
```

To explicitly force all non-cluster DNS lookups to go through a specific nameserver at 172.16.0.1, point the `proxy` and `upstream` to the nameserver instead of `/etc/resolv.conf`
To explicitly force all non-cluster DNS lookups to go through a specific nameserver at 172.16.0.1, point the `forward` to the nameserver instead of `/etc/resolv.conf`

```
proxy . 172.16.0.1
forward . 172.16.0.1
```
```
upstream 172.16.0.1
```

The final ConfigMap along with the default `Corefile` configuration looks like:

Expand All @@ -147,11 +144,11 @@ data:
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream 172.16.0.1
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . 172.16.0.1
forward . 172.16.0.1
cache 30
loop
reload
Expand All @@ -160,10 +157,12 @@ data:
consul.local:53 {
errors
cache 30
proxy . 10.150.0.1
forward . 10.150.0.1
}
```
In Kubernetes version 1.10 and later, kubeadm supports automatic translation of the CoreDNS ConfigMap from the kube-dns ConfigMap.
***Note: While kube-dns accepts a service name (eg: ns.foo.com) for stubdomain and nameserver, CoreDNS does not support this feature.
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During translation, if a service name is detected, it will be omitted while translating to the equivalent CoreDNS config.***
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## Kube-dns

Expand Down Expand Up @@ -308,7 +307,7 @@ data:
## CoreDNS configuration equivalent to kube-dns

CoreDNS supports the features of kube-dns and more.
A ConfigMap created for kube-dns to support `StubDomains`and `upstreamNameservers` translates to the `proxy` plugin in CoreDNS.
A ConfigMap created for kube-dns to support `StubDomains`and `upstreamNameservers` translates to the `forward` plugin in CoreDNS.
Similarly, the `Federations` plugin in kube-dns translates to the `federation` plugin in CoreDNS.

### Example
Expand Down Expand Up @@ -341,12 +340,12 @@ federation cluster.local {
abc.com:53 {
errors
cache 30
proxy . 1.2.3.4
forward . 1.2.3.4
}
my.cluster.local:53 {
errors
cache 30
proxy . 2.3.4.5
forward . 2.3.4.5
}
```

Expand All @@ -357,26 +356,26 @@ The complete Corefile with the default plugins:
errors
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
upstream 8.8.8.8 8.8.4.4
upstream
pods insecure
fallthrough in-addr.arpa ip6.arpa
}
federation cluster.local {
foo foo.feddomain.com
}
prometheus :9153
proxy . 8.8.8.8 8.8.4.4
forward . 8.8.8.8 8.8.4.4
cache 30
}
abc.com:53 {
errors
cache 30
proxy . 1.2.3.4
forward . 1.2.3.4
}
my.cluster.local:53 {
errors
cache 30
proxy . 2.3.4.5
forward . 2.3.4.5
}
```

Expand Down