*`binDir` (string, optional): additional directory for CNI plugins which multus calls, in addition to the default (the default is typically set to `/opt/cni/bin`)
*`kubeconfig` (string, optional): kubeconfig file for the out of cluster communication with kube-apiserver. See the example [kubeconfig](https://github.com/k8snetworkplumbingwg/multus-cni/blob/master/docs/node-kubeconfig.yaml). If you would like to use CRD (i.e. network attachment definition), this is required
*`namespaceIsolation` (boolean, optional): Enables a security feature where pods are only allowed to access `NetworkAttachmentDefinitions` in the namespace where the pod resides. Defaults to false.
*`capabilities` ({}list, optional): [capabilities](https://github.com/containernetworking/cni/blob/master/CONVENTIONS.md#dynamic-plugin-specific-fields-capabilities--runtime-configuration) supported by at least one of the delegates. (NOTE: Multus only supports portMappings/Bandwidth capability for cluster networks).
*`clusterNetwork` (string, required): default CNI network for pods, used in kubernetes cluster (Pod IP and so on): name of network-attachment-definition, CNI json file name (without extension, .conf/.conflist), directory for CNI config file or absolute file path for CNI config file
*`defaultNetworks` ([]string, required): default CNI network attachment: name of network-attachment-definition, CNI json file name (without extension, .conf/.conflist), directory for CNI config file or absolute file path for CNI config file
1. CNI json config file in `confDir`. Given name should be without extension, like .conf/.conflist. (e.g. "test" for "test.conf"). The given name for `clusterNetwork` should match the value for `name` key in the config file (e.g. `"name": "test"` in "test.conf" when `"clusterNetwork": "test"`)
1. Multus failed to find network. Multus raise error message
## Miscellaneous config
### Default Network Readiness Indicator
You may wish for your "default network" (that is, the CNI plugin & its configuration you specify as your default delegate) to become ready before you attach networks with Multus. This is disabled by default and not used unless you add the readiness check option(s) to your CNI configuration file.
For example, if you use Flannel as a default network, the recommended method for Flannel to be installed is via a daemonset that also drops a configuration file in `/etc/cni/net.d/`. This may apply to other plugins that place that configuration file upon their readiness, hence, Multus uses their configuration filename as a semaphore and optionally waits to attach networks to pods until that file exists.
In this manner, you may prevent pods from crash looping, and instead wait for that default network to be ready.
Only one option is necessary to configure this functionality:
*NOTE*: If `readinessindicatorfile` is unset, or is an empty string, this functionality will be disabled, and is disabled by default.
### Logging
You may wish to enable some enhanced logging for Multus, especially during the process where you're configuring Multus and need to understand what is or isn't working with your particular configuration.
By default, Multus will log via `STDERR`, which is the standard method by which CNI plugins communicate errors, and these errors are logged by the Kubelet.
Optionally, you may disable this method by setting the `logToStderr` option in your CNI configuration:
Optionally, you may have Multus log to a file on the filesystem. This file will be written locally on each node where Multus is executed. You may configure this via the `LogFile` option in the CNI configuration. By default this additional logging to a flat file is disabled.
For example in your CNI configuration, you may set:
The functionality provided by the `namespaceIsolation` configuration option enables a mode where Multus only allows pods to access custom resources (the `NetworkAttachmentDefinitions`) within the namespace where that pod resides. In other words, the `NetworkAttachmentDefinitions` are isolated to usage within the namespace in which they're created.
**NOTE**: The default namespace is special in this scenario. Even with namespace isolation enabled, any pod, in any namespace is allowed to refer to `NetworkAttachmentDefinitions` in the default namespace. This allows you to create commonly used unprivileged `NetworkAttachmentDefinitions` without having to put them in all namespaces. For example, if you had a `NetworkAttachmentDefinition` named `foo` the default namespace, you may reference it in an annotation with: `default/foo`.
For example, if a pod is created in the namespace called `development`, Multus will not allow networks to be attached when defined by custom resources created in a different namespace, say in the `default` network.
Consider the situation where you have a system that has users of different privilege levels -- as an example, a platform which has two administrators: a Senior Administrator and a Junior Administrator. The Senior Administrator may have access to all namespaces, and some network configurations as used by Multus are considered to be privileged in that they allow access to some protected resources available on the network. However, the Junior Administrator has access to only a subset of namespaces, and therefore it should be assumed that the Junior Administrator cannot create pods in their limited subset of namespaces. The `namespaceIsolation` feature provides for this isolation, allowing pods created in given namespaces to only access custom resources in the same namespace as the pod.
Namespace Isolation is disabled by default.
#### Configuration example
```
"namespaceIsolation": true,
```
#### Usage example
Let's setup an example where we:
* Create a custom resource in a namespace called `privileged`
* Create a pod in a namespace called `development`, and have annotations that reference a custom resource in the `privileged` namespace. The creation of this pod should be disallowed by Multus (as we'll have the use of the custom resources limited only to those custom resources created within the same namespace as the pod).
Given the above scenario with a Junior & Senior Administrator. You may assume that the Senior Administrator has access to all namespaces, whereas the Junior Administrator has access only to the `development` namespace.
Firstly, we show that we have a number of namespaces available:
```
# List the available namespaces
[user@kube-master ~]$ kubectl get namespaces
NAME STATUS AGE
default Active 7h27m
development Active 3h
kube-public Active 7h27m
kube-system Active 7h27m
privileged Active 4s
```
We'll create a `NetworkAttachmentDefinition` in the `privileged` namespace.
```
# Show the network attachment definition we're creating.
[user@kube-master ~]$ cat cr.yml
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
name: macvlan-conf
spec:
config: '{
"cniVersion": "0.3.0",
"type": "macvlan",
"master": "eth0",
"mode": "bridge",
"ipam": {
"type": "host-local",
"subnet": "192.168.1.0/24",
"rangeStart": "192.168.1.200",
"rangeEnd": "192.168.1.216",
"routes": [
{ "dst": "0.0.0.0/0" }
],
"gateway": "192.168.1.1"
}
}'
# Create that network attachment definition in the privileged namespace
networkattachmentdefinition.k8s.cni.cncf.io/macvlan-conf created
# List the available network attachment definitions in the privileged namespace.
[user@kube-master ~]$ kubectl get networkattachmentdefinition.k8s.cni.cncf.io -n privileged
NAME AGE
macvlan-conf 11s
```
Next, we'll create a pod with an annotation that references the privileged namespace. Pay particular attention to the annotation that reads `k8s.v1.cni.cncf.io/networks: privileged/macvlan-conf` -- where it contains a reference to a `namespace/configuration-name` formatted network attachment name. In this case referring to the `macvlan-conf` in the namespace called `privileged`.
2018-12-18T21:41:32Z [error] GetNetworkDelegates: namespace isolation enabled, annotation violates permission, pod is in namespace development but refers to target namespace privileged
This error expresses that the pod resides in the namespace named `development` but refers to a `NetworkAttachmentDefinition` outside of that namespace, in this case, the namespace named `privileged`.
In a positive example, you'd instead create the `NetworkAttachmentDefinition` in the `development` namespace, and you'd have an annotation that either A. does not reference a namespace, or B. refers to the same annotation.
A positive example may be:
```
# Create the same NetworkAttachmentDefinition as above, however in the development namespace
[user@kube-master ~]$ kubectl create -f cr.yml -n development
networkattachmentdefinition.k8s.cni.cncf.io/macvlan-conf created
# Show the yaml for a sample pod which references macvlan-conf without a namspace/ format
### Allow specific namespaces to be used across namespaces when using namespace isolation
The `globalNamespaces` configuration option is only used when `namespaceIsolation` is set to true. `globalNamespaces` specifies a comma-delimited list of namespaces which can be referred to from outside of any given namespace in which a pod resides.
Note that when using `globalNamespaces` the `default` namespace must be specified in the list if you wish to use that namespace, when `globalNamespaces` is not set, the `default` namespace is implied to be used across namespaces.
### Specify default cluster network in Pod annotations
Users may also specify the default network for any given pod (via annotation), for cases where there are multiple cluster networks available within a Kubernetes cluster.
1. During a migration from one default network to another (e.g. from Flannel to Calico), it may be practical if both network solutions are able to operate in parallel. Users can then control which network a pod should attach to during the transition period.
2. Some users may deploy multiple cluster networks for the sake of their security considerations, and may desire to specify the default network for individual pods.
Follow these steps to specify the default network on a pod-by-pod basis:
1. First, you need to define all your cluster networks as network-attachment-definition objects.
2. Next, you can specify the network you want in pods with the `v1.multus-cni.io/default-network` annotation. Pods which do not specify this annotation will keep using the CNI as defined in the Multus config file.
