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Update content on kube-dns to coredns configmap translation (#13826)

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Updates and corrects the part of configmap for CoreDNS
This commit is contained in:
Sandeep Rajan
2019-04-25 14:31:46 -04:00
committed by Kubernetes Prow Robot
parent 111e6d1e57
commit 22441ecaee
1 changed files with 16 additions and 22 deletions
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content/en/docs/tasks/administer-cluster/dns-custom-nameservers.md
+16 -22
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@@ -78,11 +78,10 @@ data:
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . /etc/resolv.conf
forward . /etc/resolv.conf
cache 30
loop
reload
@@ -97,10 +96,8 @@ The Corefile configuration includes the following [plugins](https://coredns.io/p
> The `pods insecure` option is provided for backward compatibility with kube-dns. You can use the `pods verified` option, which returns an A record only if there exists a pod in same namespace with matching IP. The `pods disabled` option can be used if you don't use pod records.
> `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.
@@ -110,7 +107,7 @@ 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.
@@ -119,18 +116,15 @@ 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:
@@ -147,11 +141,10 @@ data:
health
kubernetes cluster.local in-addr.arpa ip6.arpa {
pods insecure
upstream 172.16.0.1
fallthrough in-addr.arpa ip6.arpa
}
prometheus :9153
proxy . 172.16.0.1
forward . 172.16.0.1
cache 30
loop
reload
@@ -160,10 +153,12 @@ 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 an FQDN for stubdomain and nameserver (eg: ns.foo.com), CoreDNS does not support this feature.
During translation, all FQDN nameservers will be omitted from the CoreDNS config.***
## Kube-dns
@@ -308,7 +303,7 @@ 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
@@ -341,12 +336,12 @@ 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
}
```
@@ -357,7 +352,6 @@ 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
pods insecure
fallthrough in-addr.arpa ip6.arpa
}
@@ -365,18 +359,18 @@ The complete Corefile with the default plugins:
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
}
```