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@@ -36,7 +36,8 @@ After a few seconds, a Weave Net pod should be running on each
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Node and any further pods you create will be automatically attached to the Weave
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network.
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**Note:** This command requires Kubernetes 1.4 or later.
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**Note:** This command requires Kubernetes 1.4 or later, and we
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recommend your master node has at least two CPU cores.
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> CNI, the [_Container Network Interface_](https://github.com/containernetworking/cni),
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> is a proposed standard for configuring network interfaces for Linux
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@@ -97,21 +98,26 @@ and so you will need to perform the procedure manually:
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Kubernetes manages
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[resources](https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/)
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on each node, and will only schedule pods to run on nodes which have
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enough free resources. A typical Kubernetes install will have
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components (etcd, scheduler, api-server, ...) totalling 95% of one
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CPU, leaving very little room to run anything else. Yet Weave Net
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must run on every node, including master, for all features to work.
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on each node, and only schedules pods to run on nodes that have enough
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free resources.
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The best way to resolve this is to use machines with at least two CPU
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cores. However, people installing for the first time will probably not
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know this, so we write into the DaemonSet specification that Weave Net
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only needs 1% CPU for each container, and thus it will start up on a
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single-CPU node.
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The components of a typical Kubernetes installation (with the master
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node running etcd, scheduler, api-server, etc.) take up about 95% of a
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CPU, which leaves little room to run anything else. For all of Weave
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Net's features to work, it must run on every node, including the
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master.
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Weave Net will, depending on workload, need more than 1% of CPU, but
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the number in the DaemonSet is a minimum request, not a limit, so
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Weave Net can "burst" above that level.
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The best way to resolve this issue is to use machines with at least
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two CPU cores. However if you are installing Kubernetes and Weave Net
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for the first time, you may not be aware of this requirement. For this
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reason, Weave Net launches as a DaemonSet with a specification that
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reserves at least 1% CPU for each container. This enables Weave Net to
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start up seamlessly on a single-CPU node.
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Depending on the workload, Weave Net may need more than 1% of the
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CPU. The percentage set in the DaemonSet is the minimum and not a
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limit. This minimum setting allows Weave Net to take advantage of
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available CPU and "burst" above that limit if it needs to.
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## <a name="eviction"></a>Pod Eviction
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@@ -121,13 +127,15 @@ one or more pods. It may choose to evict the Weave Net pod, which will
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disrupt pod network operations.
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You can reduce the chance of eviction by changing the DaemonSet to
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have a much bigger request, and a limit of the same value. This will
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cause Kubernetes to apply ["guaranteed" rather than "burstable"
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policy](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/resource-qos.md).
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However there is no similar request for disk space, so you should be
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aware of this issue and monitor your resources to stay below 100%.
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have a much bigger request, and a limit of the same value.
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Kubernetes will give a notification in the event of an eviction, like this:
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This causes Kubernetes to apply a ["guaranteed" rather than a
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"burstable" policy](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/resource-qos.md).
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However a similar request for disk space can not
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be made, and so please be aware of this issue and monitor your
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resources to ensure that they stay below 100%.
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Kubernetes displays a notification in the event of an eviction similar to this:
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```
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pod weave-net-4ozht_kube-system(546acee0-ee25-11e6-8965-068f417b4097) evicted successfully
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