---
title: Integrating Kubernetes via the Addon
menu_order: 63
---
The following topics are discussed:
* [Installation](#install)
* [Network Policy Controller](#npc)
* [Upgrading the Daemon Sets](#daemon-sets)
* [Network Policy Controller](#npc)
* [Troubleshooting Blocked Connections](#blocked-connections)
* [Changing Configuration Options](#configuration-options)
## Installation
Weave Net can be installed onto your CNI-enabled Kubernetes cluster
with a single command:
```
kubectl apply -f https://git.io/weave-kube
```
After a few seconds, a Weave Net pod should be running on each
Node and any further pods you create will be automatically attached to the Weave
network.
**Note:** This command requires Kubernetes 1.4 or later.
> CNI, the [_Container Network Interface_](https://github.com/containernetworking/cni),
> is a proposed standard for configuring network interfaces for Linux
> containers.
>
> If you do not already have a CNI-enabled cluster, you can bootstrap
> one easily with
> [kubeadm](http://kubernetes.io/docs/getting-started-guides/kubeadm/).
>
> Alternatively, you can [configure CNI yourself](http://kubernetes.io/docs/admin/network-plugins/#cni)
**Note:** If using the [Weave CNI
Plugin](/site/cni-plugin.md) from a prior full install of Weave Net with your
cluster, you must first uninstall it before applying the Weave-kube addon.
Shut down Kubernetes, and _on all nodes_ perform the following:
* `weave reset`
* Remove any separate provisions you may have made to run Weave at
boot-time, e.g. `systemd` units
* `rm /opt/cni/bin/weave-*`
Then relaunch Kubernetes and install the addon as described
above.
The URL [https://git.io/weave-kube](https://git.io/weave-kube) points
to the YAML file for the latest release of the Weave Net addon.
Historic versions are archived on our [GitHub release
page](https://github.com/weaveworks/weave/releases).
### Upgrading the Daemon Sets
Kubernetes does not currently support rolling upgrades of daemon sets,
and so you will need to perform the procedure manually:
* Apply the updated addon manifest `kubectl apply -f https://git.io/weave-kube`
* Kill each Weave Net pod with `kubectl delete` and then wait for it to reboot before moving on to the next pod.
**Note:** If you delete all Weave Net pods at the same time they will
lose track of IP address range ownership, possibly leading to
duplicate IP addresses if you then start a new copy of Weave Net.
##Network Policy Controller
The addon also supports the [Kubernetes policy
API](http://kubernetes.io/docs/user-guide/networkpolicies/) so that
you can securely isolate pods from each other based on namespaces and
labels. For more information on configuring network policies in
Kubernetes see the
[walkthrough](http://kubernetes.io/docs/getting-started-guides/network-policy/walkthrough/)
and the [NetworkPolicy API object
definition](http://kubernetes.io/docs/api-reference/extensions/v1beta1/definitions/#_v1beta1_networkpolicy).
**Note:** as of version 1.9 of Weave Net, the Network Policy
Controller allows all multicast traffic. Since a single multicast
address may be used by multiple pods, we cannot implement rules to
isolate them individually. You can turn this behaviour off (block
all multicast traffic) by adding `--allow-mcast` as an argument to
`weave-npc` in the YAML configuration.
### Troubleshooting Blocked Connections
If you suspect that legitimate traffic is being blocked by the Weave Network Policy Controller, the first thing to do is check the `weave-npc` container's logs.
To do this, first you have to find the name of the Weave Net pod running on the relevant host:
```
$ kubectl get pods -n kube-system -o wide | grep weave-net
weave-net-08y45 2/2 Running 0 1m 10.128.0.2 host1
weave-net-2zuhy 2/2 Running 0 1m 10.128.0.4 host3
weave-net-oai50 2/2 Running 0 1m 10.128.0.3 host2
```
Select the relevant container, for example, if you want to look at host2 then pick `weave-net-oai50` and run:
```
$ kubectl logs -n kube-system weave-npc
```
When the Weave Network Policy Controller blocks a connection, it logs the following details about it:
* protocol used,
* source IP and port,
* destination IP and port,
as per the below example:
```
TCP connection from 10.32.0.7:56648 to 10.32.0.11:80 blocked by Weave NPC.
UDP connection from 10.32.0.7:56648 to 10.32.0.11:80 blocked by Weave NPC.
```
### Changing Configuration Options
The default configuration settings can be changed by saving and editing the
addon YAML before running `kubectl apply`. Additional arguments may be
supplied to the Weave router process by adding them to the `command:`
array in the YAML file.
Some parameters are changed by environment variables; these can be
inserted into the YAML file like this:
```
containers:
- name: weave
env:
- name: IPALLOC_RANGE
value: 10.0.0.0/16
```
The list of variables you can set is:
* CHECKPOINT\_DISABLE - if set to 1, disable checking for new Weave Net
versions (default is blank, i.e. check is enabled)
* IPALLOC\_RANGE - the range of IP addresses used by Weave Net
and the subnet they are placed in (CIDR format; default 10.32.0.0/12)
* EXPECT\_NPC - set to 0 to disable Network Policy Controller (default is on)
* KUBE\_PEERS - list of addresses of peers in the Kubernetes cluster
(default is to fetch the list from the api-server)
* IPALLOC\_INIT - set the initialization mode of the [IP Address
Manager](/site/operational-guide/concepts.md#ip-address-manager)
(defaults to consensus amongst the KUBE\_PEERS)
* WEAVE\_EXPOSE\_IP - set the IP address used as a gateway from the
Weave network to the host network - this is useful if you are
configuring the addon as a static pod.
* WEAVE\_MTU - Weave Net defaults to 1376 bytes, but you can set a
smaller size if your underlying network has a tighter limit, or set
a larger size for better performance if your network supports jumbo
frames - see [here](/site/using-weave/fastdp.md#mtu) for more
details.