Integrating Kubernetes via the Addon

The following topics are discussed:

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, 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.

Alternatively, you can configure CNI yourself

Note: If using the Weave CNI Plugin 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 points to the YAML file for the latest release of the Weave Net addon. Historic versions are archived on our GitHub release page.

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 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 and the NetworkPolicy API object definition.

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 <weave-pod-name-as-above> -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 (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 for more details.

https://www.weave.works/docs/net/latest/kube-addon/

https://yum.dockerproject.org/repo/main/centos/7/Packages/

http://blog.csdn.net/horsefoot/article/details/54018103