kubeadm: add notes about deprecating kube-dns usage in 1.18 (#18851)

* kubeadm: add notes about deprecating kube-dns usage in 1.18 * implementation-details: update notes about DNS
2020-02-07 21:29:45 +02:00
parent 6909798afd
commit fb1c0e8b77
4 changed files with 17 additions and 17 deletions
@@ -447,21 +447,11 @@ A ServiceAccount for `kube-proxy` is created in the `kube-system` namespace; the

 #### DNS

-Note that:
-
+- In Kubernetes version 1.18 kube-dns usage with kubeadm is deprecated and will be removed in a future release
 - The CoreDNS service is named `kube-dns`. This is done to prevent any interruption
 in service when the user is switching the cluster DNS from kube-dns to CoreDNS or vice-versa
- In Kubernetes version 1.10 and earlier, you must enable CoreDNS with `--feature-gates=CoreDNS=true`
- In Kubernetes version 1.11 and 1.12, CoreDNS is the default DNS server and you must
-invoke kubeadm with `--feature-gates=CoreDNS=false` to install kube-dns instead
- In Kubernetes version 1.13 and later, the `CoreDNS` feature gate is no longer available and kube-dns can be installed using the `--config` method described [here](/docs/reference/setup-tools/kubeadm/kubeadm-init-phase/#cmd-phase-addon)
-
-
-A ServiceAccount for CoreDNS/kube-dns is created in the `kube-system` namespace.
-
-Deploy the `kube-dns` Deployment and Service:
-
- It's the upstream CoreDNS deployment relatively unmodified
+the `--config` method described [here](/docs/reference/setup-tools/kubeadm/kubeadm-init-phase/#cmd-phase-addon)
+- A ServiceAccount for CoreDNS/kube-dns is created in the `kube-system` namespace.
 - The `kube-dns` ServiceAccount is bound to the privileges in the `system:kube-dns` ClusterRole

 ## kubeadm join phases internal design
@@ -157,6 +157,8 @@ dns:
  type: "kube-dns"
 ```

+Please note that kube-dns usage with kubeadm is deprecated as of v1.18 and will be removed in a future release.
+
 For more details on each field in the `v1beta2` configuration you can navigate to our
 [API reference pages.] (https://godoc.org/k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta2)

@@ -67,10 +67,14 @@ following steps:

 1. Installs a DNS server (CoreDNS) and the kube-proxy addon components via the API server.
   In Kubernetes version 1.11 and later CoreDNS is the default DNS server.
-   To install kube-dns instead of CoreDNS, the DNS addon has to be configured in the kubeadm `ClusterConfiguration`. For more information about the configuration see the section
-   `Using kubeadm init with a configuration file` below.
+   To install kube-dns instead of CoreDNS, the DNS addon has to be configured in the kubeadm `ClusterConfiguration`.
+   For more information about the configuration see the section `Using kubeadm init with a configuration file` below.
   Please note that although the DNS server is deployed, it will not be scheduled until CNI is installed.

+   {{< warning >}}
+   kube-dns usage with kubeadm is deprecated as of v1.18 and will be removed in a future release.
+   {{< /warning >}}
+
 ### Using init phases with kubeadm {#init-phases}

 Kubeadm allows you to create a control-plane node in phases using the `kubeadm init phase` command.
@@ -63,6 +63,10 @@ In Kubernetes 1.11, CoreDNS has graduated to General Availability (GA)
 and is installed by default.
 {{< /note >}}

+{{< warning >}}
+In Kubernetes 1.18, kube-dns usage with kubeadm has been deprecated and will be removed in a future version.
+{{< /warning >}}
+
 To install kube-dns on versions prior to 1.13, set the `CoreDNS` feature gate
 value to `false`:

@@ -72,9 +76,9 @@ kubeadm init --feature-gates=CoreDNS=false

 For versions 1.13 and later, follow the guide outlined [here](/docs/reference/setup-tools/kubeadm/kubeadm-init-phase#cmd-phase-addon).

-## Upgrading CoreDNS 
+## Upgrading CoreDNS

-CoreDNS is available in Kubernetes since v1.9. 
+CoreDNS is available in Kubernetes since v1.9.
 You can check the version of CoreDNS shipped with Kubernetes and the changes made to CoreDNS [here](https://github.com/coredns/deployment/blob/master/kubernetes/CoreDNS-k8s_version.md).

 CoreDNS can be upgraded manually in case you want to only upgrade CoreDNS or use your own custom image.