Skip to content
Permalink
Browse files

IPv4/IPv6 dual stack docs (#16010)

* initial commit for IPv4/IPv6 dual stack docs

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Apply suggestions from code review

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Remove warning, Add What's next section

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Add Service section
Add Provising a dual stack Kubernetes cluster section
Add Ecosystem tooling section
Update prerequisites
Update flags
Update supported features
Move validation to task
Add Service validation

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Apply suggestions from code review

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Remove ecosystem tooling
Remove provisioning tools
Add backtics to ipFamily values
Update loadbalancer section

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Fix feature gate link typo

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Update to dual-stack
Add default use-case to Service validation
Add note to default Service behaviour
Add default Service example
Update egress routing description

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Update api-server to the API server
Fix small typo based on feedback

Co-Authored-By: Tim Bannister <tim@scalefactory.com>
Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Add for_k8s_version feature state

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Update service IP address verbiage to be more concise

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Move to tasks/network

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Move dual-stack under services-networking

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Remove dual-stack from glossary
Add codenew blocks
Split command from output
Renamed pod name
Created subheading to validate node and pod addressing

Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Apply suggestions from code review

Co-Authored-By: Tim Bannister <tim@scalefactory.com>

* Verbiage update based on review

Co-Authored-By: Tim Bannister <tim@scalefactory.com>
Signed-off-by: Lachlan Evenson <lachlan.evenson@microsoft.com>

* Apply suggestions from code review

Co-Authored-By: Tim Bannister <tim@scalefactory.com>
  • Loading branch information...
2 people authored and k8s-ci-robot committed Sep 9, 2019
1 parent 5b2906c commit 610f7066752faf343b20d2dd54fa64ab7c67a8ff
@@ -0,0 +1,111 @@
---
reviewers:
- lachie83
- khenidak
- aramase
title: IPv4/IPv6 dual-stack
feature:
title: IPv4/IPv6 dual-stack
description: >
Allocation of IPv4 and IPv6 addresses to Pods and Services
content_template: templates/concept
weight: 70
---

{{% capture overview %}}

{{< feature-state for_k8s_version="v1.16" state="alpha" >}}

IPv4/IPv6 dual-stack enables the allocation of both IPv4 and IPv6 addresses to {{< glossary_tooltip text="Pods" term_id="pod" >}} and {{< glossary_tooltip text="Services" term_id="service" >}}.

If you enable IPv4/IPv6 dual-stack networking for your Kubernetes cluster, the cluster will support the simultaneous assignment of both IPv4 and IPv6 addresses.

{{% /capture %}}

{{% capture body %}}

## Supported Features

Enabling IPv4/IPv6 dual-stack on your Kubernetes cluster provides the following features:

* Dual-stack Pod networking (a single IPv4 and IPv6 address assignment per Pod)
* IPv4 and IPv6 enabled Services (each Service must be for a single address family)
* Kubenet multi address family support (IPv4 and IPv6)
* Pod off-cluster egress routing (eg. the Internet) via both IPv4 and IPv6 interfaces

## Prerequisites

The following prerequisites are needed in order to utilize IPv4/IPv6 dual-stack Kubernetes clusters:

* Kubernetes 1.16 or later
* Provider support for dual-stack networking (Cloud provider or otherwise must be able to provide Kubernetes nodes with routable IPv4/IPv6 network interfaces)
* Kubenet network plugin
* Kube-proxy running in mode IPVS

## Enable IPv4/IPv6 dual-stack

To enable IPv4/IPv6 dual-stack, enable the `IPv6DualStack` [feature gate](https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/) for the relevant components of your cluster, and set dual-stack cluster network assignments:

* kube-controller-manager:
* `--feature-gates="IPv6DualStack=true"`
* `--cluster-cidr=<IPv4 CIDR>,<IPv6 CIDR>` eg. `--cluster-cidr=10.244.0.0/16,fc00::/24`
* `--service-cluster-ip-range=<IPv4 CIDR>,<IPv6 CIDR>`
* kubelet:
* `--feature-gates="IPv6DualStack=true"`
* kube-proxy:
* `--proxy-mode=ipvs`
* `--cluster-cidrs=<IPv4 CIDR>,<IPv6 CIDR>`
* `--feature-gates="IPv6DualStack=true"`

{{< caution >}}
If you specify an IPv6 address block larger than a /24 via `--cluster-cidr` on the command line, that assignment will fail.
{{< /caution >}}

## Services

If your cluster has IPv4/IPv6 dual-stack networking enabled, you can create {{< glossary_tooltip text="Services" term_id="service" >}} with either an IPv4 or an IPv6 address. You can choose the address family for the Service's cluster IP by setting a field, `.spec.ipFamily`, on that Service.
You can only set this field when creating a new Service. Setting the `.spec.ipFamily` field is optional and should only be used if you plan to enable IPv4 and IPv6 {{< glossary_tooltip text="Services" term_id="service" >}} and {{< glossary_tooltip text="Ingresses" term_id="ingress" >}} on your cluster. The configuration of this field not a requirement for [egress](#egress-traffic) traffic.

{{< note >}}
The default address family for your cluster is the address family of the first service cluster IP range configured via the `--service-cluster-ip-range` flag to the kube-controller-manager.
{{< /note >}}

You can set `.spec.ipFamily` to either:

* `IPv4`: The API server will assign an IP from a `service-cluster-ip-range` that is `ipv4`
* `IPv6`: The API server will assign an IP from a `service-cluster-ip-range` that is `ipv6`

The following Service specification does not include the `ipFamily` field. Kubernetes will assign an IP address (also known as a "cluster IP") from the first configured `service-cluster-ip-range` to this Service.

{{< codenew file="service/networking/dual-stack-default-svc.yaml" >}}

The following Service specification includes the `ipFamily` field. Kubernetes will assign an IPv6 address (also known as a "cluster IP") from the configured `service-cluster-ip-range` to this Service.

{{< codenew file="service/networking/dual-stack-ipv6-svc.yaml" >}}

For comparison, the following Service specification will be assigned an IPV4 address (also known as a "cluster IP") from the configured `service-cluster-ip-range` to this Service.

{{< codenew file="service/networking/dual-stack-ipv4-svc.yaml" >}}

### Type LoadBalancer

On cloud providers which support IPv6 enabled external load balancers, setting the `type` field to `LoadBalancer` in additional to setting `ipFamily` field to `IPv6` provisions a cloud load balancer for your Service.

## Egress Traffic

The use of publicly routable and non-publicly routable IPv6 address blocks is acceptable provided the underlying {{< glossary_tooltip text="CNI" term_id="cni" >}} provider is able to implement the transport. If you have a Pod that uses non-publicly routable IPv6 and want that Pod to reach off-cluster destinations (eg. the public Internet), you must set up IP masquerading for the egress traffic and any replies. The [ip-masq-agent](https://github.com/kubernetes-incubator/ip-masq-agent) is dual-stack aware, so you can use ip-masq-agent for IP masquerading on dual-stack clusters.

## Known Issues

* IPv6 network block assignment uses the default IPv4 CIDR block size (/24)
* Kubenet forces IPv4,IPv6 positional reporting of IPs (--cluster-cidr)
* Dual-stack networking does not function if the `EndpointSlice` feature gate is enabled.

{{% /capture %}}

{{% capture whatsnext %}}

* [Validate IPv4/IPv6 dual-stack](/docs/tasks/network/validate-dual-stack) networking

{{% /capture %}}
@@ -0,0 +1,5 @@
---
title: "Network"
weight: 160
---

@@ -0,0 +1,126 @@
---
reviewers:
- lachie83
- khenidak
title: Validate IPv4/IPv6 dual-stack
content_template: templates/task
---

{{% capture overview %}}
This document shares how to validate IPv4/IPv6 dual-stack enabled Kubernetes clusters.
{{% /capture %}}

{{% capture prerequisites %}}

* Kubernetes 1.16 or later
* Provider support for dual-stack networking (Cloud provider or otherwise must be able to provide Kubernetes nodes with routable IPv4/IPv6 network interfaces)
* Kubenet network plugin
* Kube-proxy running in mode IPVS
* [Dual-stack enabled](/docs/concepts/services-networking/dual-stack/) cluster

{{% /capture %}}

{{% capture steps %}}

## Validate addressing

### Validate node addressing

Each dual-stack Node should have a single IPv4 block and a single IPv6 block allocated. Validate that IPv4/IPv6 Pod address ranges are configured by running the following command. Replace the sample node name with a valid dual-stack Node from your cluster. In this example, the Node's name is `k8s-linuxpool1-34450317-0`:

```shell
kubectl get nodes k8s-linuxpool1-34450317-0 -o go-template --template='{{range .spec.podCIDRs}}{{printf "%s\n" .}}{{end}}'
```
```
10.244.1.0/24
a00:100::/24
```
There should be one IPv4 block and one IPv6 block allocated.

Validate that the node has an IPv4 and IPv6 interface detected (replace node name with a valid node from the cluster. In this example the node name is k8s-linuxpool1-34450317-0):
```shell
kubectl get nodes k8s-linuxpool1-34450317-0 -o go-template --template='{{range .status.addresses}}{{printf "%s: %s \n" .type .address}}{{end}}'
```
```
Hostname: k8s-linuxpool1-34450317-0
InternalIP: 10.240.0.5
InternalIP: 2001:1234:5678:9abc::5
```

### Validate Pod addressing

Validate that a Pod has an IPv4 and IPv6 address assigned. (replace the Pod name with a valid Pod in your cluster. In this example the Pod name is pod01)
```shell
kubectl get pods pod01 -o go-template --template='{{range .status.podIPs}}{{printf "%s \n" .ip}}{{end}}'
```
```
10.244.1.4
a00:100::4
```

## Validate Services

Create the following Service without the `ipFamily` field set. When this field is not set, the Service gets an IP from the first configured range via `--service-cluster-ip-range` flag on the kube-controller-manager.

{{< codenew file="service/networking/dual-stack-default-svc.yaml" >}}

By viewing the YAML for the Service you can observe that the Service has the `ipFamily` field has set to reflect the address family of the first configured range set via `--service-cluster-ip-range` flag on kube-controller-manager.

```shell
kubectl get svc my-service -o yaml
```

```yaml
apiVersion: v1
kind: Service
metadata:
creationTimestamp: "2019-09-03T20:45:13Z"
labels:
app: MyApp
name: my-service
namespace: default
resourceVersion: "485836"
selfLink: /api/v1/namespaces/default/services/my-service
uid: b6fa83ef-fe7e-47a3-96a1-ac212fa5b030
spec:
clusterIP: 10.0.29.179
ipFamily: IPv4
ports:
- port: 80
protocol: TCP
targetPort: 9376
selector:
app: MyApp
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
```

Create the following Service with the `ipFamily` field set to `IPv6`.

{{< codenew file="service/networking/dual-stack-ipv6-svc.yaml" >}}

Validate that the Service gets a cluster IP address from the IPv6 address block. You may then validate access to the service via the IP and port.
```
kubectl get svc -l app=MyApp
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-service ClusterIP fe80:20d::d06b <none> 80/TCP 9s
```

### Create a dual-stack load balanced Service

If the cloud provider supports the provisioning of IPv6 enabled external load balancer, create the following Service with both the `ipFamily` field set to `IPv6` and the `type` field set to `LoadBalancer`

{{< codenew file="service/networking/dual-stack-ipv6-lb-svc.yaml" >}}

Validate that the Service receives a `CLUSTER-IP` address from the IPv6 address block along with an `EXTERNAL-IP`. You may then validate access to the service via the IP and port.
```
kubectl get svc -l app=MyApp
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
my-service ClusterIP fe80:20d::d06b 2001:db8:f100:4002::9d37:c0d7 80:31868/TCP 30s
```

{{% /capture %}}


@@ -0,0 +1,11 @@
apiVersion: v1
kind: Service
metadata:
name: my-service
spec:
selector:
app: MyApp
ports:
- protocol: TCP
port: 80
targetPort: 9376
@@ -0,0 +1,12 @@
apiVersion: v1
kind: Service
metadata:
name: my-service
spec:
ipFamily: IPv4
selector:
app: MyApp
ports:
- protocol: TCP
port: 80
targetPort: 9376
@@ -0,0 +1,15 @@
apiVersion: v1
kind: Service
metadata:
name: my-service
labels:
app: MyApp
spec:
ipFamily: IPv6
type: LoadBalancer
selector:
app: MyApp
ports:
- protocol: TCP
port: 80
targetPort: 9376
@@ -0,0 +1,12 @@
apiVersion: v1
kind: Service
metadata:
name: my-service
spec:
ipFamily: IPv6
selector:
app: MyApp
ports:
- protocol: TCP
port: 80
targetPort: 9376
@@ -95,6 +95,7 @@ toc:
- docs/concepts/services-networking/ingress.md
- docs/concepts/services-networking/network-policies.md
- docs/concepts/services-networking/add-entries-to-pod-etc-hosts-with-host-aliases.md
- docs/concepts/services-networking/dual-stack.md

- title: Storage
landing_page: /docs/concepts/storage/volumes/
@@ -126,6 +126,11 @@ toc:
- docs/tasks/tls/managing-tls-in-a-cluster.md
- docs/tasks/tls/certificate-rotation.md

- title: Network
landing_page: tasks/network/validate-dual-stack/
section:
- docs/tasks/network/validate-dual-stack.md

- title: Administer a Cluster
landing_page: /docs/tasks/administer-cluster/memory-default-namespace/
section:

0 comments on commit 610f706

Please sign in to comment.
You can’t perform that action at this time.