- MULTUS CNI plugin
- Multus is a latin word for "Multi"
- As the name suggests, it acts as a Multi plugin in Kubernetes and provides the multiple network interface support in a pod
- Multus supports all reference plugins (eg. Flannel, DHCP, Macvlan) that implement the CNI specification and all 3rd party plugins (eg. Calico, Weave, Cilium, Contiv). In addition to it, Multus supports SRIOV, SRIOV-DPDK, OVS-DPDK & VPP workloads in Kubernetes with both cloud native and NFV based applications in Kubernetes
- It is a contact between the container runtime and other plugins, and it doesn't have any of its own net configuration, it calls other plugins like flannel/calico to do the real net conf job.
- Multus reuses the concept of invoking delegates as used in flannel by grouping multiple plugins into delegates and invoking them in the sequential order of the CNI configuration file provided in json format
- The default network gets "eth0" and additional network Pod interface name as “net0”, “net1”,… “netX and so on. Multus also support interface names from the user.
- Multus is one of the projects in the Baremetal Container Experience kit.
Please check the CNI documentation for more information on container networking.
Multus may be deployed as a Daemonset, and is provided in this guide along with Flannel. Flannel is deployed as a pod-to-pod network that is used as our "default network". Each network attachment is made in addition to this default network.
Firstly, clone this GitHub repository. We'll apply files to kubectl from this repo.
We apply these files as such:
$ cat ./images/{multus-daemonset.yml,flannel-daemonset.yml} | kubectl apply -f -
Create a CNI configuration loaded as a CRD object, in this case a macvlan CNI configuration is defined. You may replace the config field with any valid CNI configuration where the CNI binary is available on the nodes.
cat <<EOF | kubectl create -f -
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"
}
}'
EOF
You may then create a pod which attached this additional interface, where the annotation correlates to the name in the NetworkAttachmentDefinition above.
cat <<EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
name: samplepod
annotations:
k8s.v1.cni.cncf.io/networks: macvlan-conf
spec:
containers:
- name: samplepod
command: ["/bin/bash", "-c", "sleep 2000000000000"]
image: dougbtv/centos-network
EOF
You may now inspect the pod and see that there is an additional interface configured, like so:
$ kubectl exec -it samplepod -- ip a
- This project is a reference implementation for Kubernetes Network Custom Resource Definition De-facto Standard. For more information refer Network Plumbing Working Group Agenda
- Kubernetes Network Custom Resource Definition De-facto Standard documentation link
- Reference implementation support following modes
- CNI config JSON in network object
- Not using CNI config (“thick” plugin usecase)
- CNI configuration stored in on-disk file
refer the section 3.2 Network Object Definition for more details in Kubernetes Network Custom Resource Definition De-facto Standard
- Refer the reference implementation presentation and demo details - link
- Release version from v3.0 is not compatible with v1.0 and v2.0 version Network Object CRD
- MULTUS CNI pluginspecifications.
This plugin requires Go 1.8 (or later) to build.
#./build
- name (string, required): the name of the network
- type (string, required): "multus"
- kubeconfig (string, optional): kubeconfig file for the out of cluster communication with kube-apiserver. See the example kubeconfig
- delegates (([]map,required): number of delegate details in the Multus
- capabilities ({}list, optional): capabilities supported by at least one of the delegates. (NOTE: Multus only supports portMappings capability for now). See the example.
Kubelet is responsible for establishing network interfaces for pods; it does this by invoking its configured CNI plugin. When Multus is invoked it retrieves network references from Pod annotation. Multus then uses these network references to get network configurations. Network configurations are defined as Kubernetes Custom Resource Object (CRD). These configurations describe which CNI plugins to invoke and what their configurations are. The order of plugin invocation is important as it identifies the primary plugin. This order is taken from network object references given in a Pod spec.
You may wish to create the network-attachment-definition manually if you haven't installed using the daemonset technique, which includes the CRD, and you can verify if it's loaded with kubectl get crd and look for the presence of network-attachment-definition.
- Create a Custom Resource Definition (CRD)
crdnetwork.yaml; for the network object using the YAML from the examples directory.
$ kubectl create -f ./examples/crd.yml
customresourcedefinition.apiextensions.k8s.io/network-attachment-definitions.k8s.cni.cncf.io created
- Run kubectl get command to check the Network CRD creation
$ kubectl get crd
NAME KIND
network-attachment-definitions.k8s.cni.cncf.io CustomResourceDefinition.v1beta1.apiextensions.k8s.io
-
After creating CRD network object you can create network resources in Kubernetes. These network resources may contain additional underlying CNI plugin parameters given in JSON format. In the following example shown below the args field contains parameters that will be passed into Flannel plugin.
-
Save the following YAML to flannel-network.yaml
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
name: flannel-networkobj
spec:
config: '{
"cniVersion": "0.3.0",
"type": "flannel",
"delegate": {
"isDefaultGateway": true
}
}'
- Create the custom resource definition
$ kubectl create -f ./flannel-network.yaml
network "flannel-networkobj" created
$ kubectl get net-attach-def
NAME AGE
flannel-networkobj 26s
- Get the custom network object details
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
clusterName: ""
creationTimestamp: 2018-05-17T09:13:20Z
deletionGracePeriodSeconds: null
deletionTimestamp: null
initializers: null
name: flannel-networkobj
namespace: default
resourceVersion: "21176114"
selfLink: /apis/k8s.cni.cncf.io/v1/namespaces/default/networks/flannel-networkobj
uid: 8ac8f873-59b2-11e8-8308-a4bf01024e6f
spec:
config: '{ "cniVersion": "0.3.0", "type": "flannel", "delegate": { "isDefaultGateway":
true } }'
- Save the following YAML to sriov-network.yaml to creating sriov network object. ( Refer to Intel - SR-IOV CNI or contact @kural in Intel-Corp Slack for running the DPDK based workloads in Kubernetes)
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
name: sriov-conf
spec:
config: '{
"type": "sriov",
"if0": "enp12s0f1",
"ipam": {
"type": "host-local",
"subnet": "10.56.217.0/24",
"rangeStart": "10.56.217.171",
"rangeEnd": "10.56.217.181",
"routes": [
{ "dst": "0.0.0.0/0" }
],
"gateway": "10.56.217.1"
}
}'
- Likewise save the following YAML to sriov-vlanid-l2enable-network.yaml to create another sriov based network object:
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
name: sriov-vlanid-l2enable-conf
spec:
config: '{
"type": "sriov",
"if0": "enp2s0",
"vlan": 210,
"l2enable": true
}'
-
Follow step 3 above to create "sriov-vlanid-l2enable-conf" and "sriov-conf" network objects
-
View network objects using kubectl
# kubectl get net-attach-def
NAME AGE
flannel-networkobj 29m
sriov-conf 6m
sriov-vlanid-l2enable-conf 2m
- Create a Mutlus CNI configuration file on each Kubernetes node. This file should be created in: /etc/cni/net.d/multus-cni.conf with the content shown below. Use only the absolute path to point to the kubeconfig file (as it may change depending upon your cluster env). We are assuming all CNI plugin binaries are default location (
/opt/cni/bin dir)
{
"name": "node-cni-network",
"type": "multus",
"kubeconfig": "/etc/kubernetes/node-kubeconfig.yaml"
}
- Many users want Kubernetes default networking feature along with network objects. Refer to issues #14 & #17 for more information. In the following Multus configuration, Weave act as the default network in the absence of network field in the pod metadata annotation.
{
"name": "node-cni-network",
"type": "multus",
"kubeconfig": "/etc/kubernetes/node-kubeconfig.yaml",
"delegates": [{
"type": "weave-net",
"hairpinMode": true
}]
}
Configurations referenced in annotations are created in addition to the default network.
- Save the following YAML to pod-multi-network.yaml. In this case flannel-conf network object acts as the primary network.
# cat pod-multi-network.yaml
apiVersion: v1
kind: Pod
metadata:
name: multus-multi-net-poc
annotations:
k8s.v1.cni.cncf.io/networks: '[
{ "name": "flannel-conf" },
{ "name": "sriov-conf" },
{ "name": "sriov-vlanid-l2enable-conf",
"interfaceRequest": "north" }
]'
spec: # specification of the pod's contents
containers:
- name: multus-multi-net-poc
image: "busybox"
command: ["top"]
stdin: true
tty: true
- Create Multiple network based pod from the master node
# kubectl create -f ./pod-multi-network.yaml
pod "multus-multi-net-poc" created
- Get the details of the running pod from the master
# kubectl get pods
NAME READY STATUS RESTARTS AGE
multus-multi-net-poc 1/1 Running 0 30s
- Run
ifconfigcommand in Pod:
# kubectl exec -it multus-multi-net-poc -- ifconfig
eth0 Link encap:Ethernet HWaddr C6:43:7C:09:B4:9C
inet addr:10.128.0.4 Bcast:0.0.0.0 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:648 (648.0 B) TX bytes:42 (42.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
net0 Link encap:Ethernet HWaddr 06:21:91:2D:74:B9
inet addr:192.168.42.3 Bcast:0.0.0.0 Mask:255.255.255.0
inet6 addr: fe80::421:91ff:fe2d:74b9/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1450 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 B) TX bytes:648 (648.0 B)
net1 Link encap:Ethernet HWaddr D2:94:98:82:00:00
inet addr:10.56.217.171 Bcast:0.0.0.0 Mask:255.255.255.0
inet6 addr: fe80::d094:98ff:fe82:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:120 (120.0 B) TX bytes:648 (648.0 B)
north Link encap:Ethernet HWaddr BE:F2:48:42:83:12
inet6 addr: fe80::bcf2:48ff:fe42:8312/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1420 errors:0 dropped:0 overruns:0 frame:0
TX packets:1276 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:95956 (93.7 KiB) TX bytes:82200 (80.2 KiB)
| Interface name | Description |
|---|---|
| lo | loopback |
| eth0 | weave network interface |
| net0 | Flannel network tap interface |
| net1 | VF0 of NIC 1 assigned to the container by Intel - SR-IOV CNI plugin |
| north | VF0 of NIC 2 assigned with VLAN ID 210 to the container by SR-IOV CNI plugin |
- Check the vlan ID of the NIC 2 VFs
# ip link show enp2s0
20: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
link/ether 24:8a:07:e8:7d:40 brd ff:ff:ff:ff:ff:ff
vf 0 MAC 00:00:00:00:00:00, vlan 210, spoof checking off, link-state auto
vf 1 MAC 00:00:00:00:00:00, vlan 4095, spoof checking off, link-state auto
vf 2 MAC 00:00:00:00:00:00, vlan 4095, spoof checking off, link-state auto
vf 3 MAC 00:00:00:00:00:00, vlan 4095, spoof checking off, link-state auto
Given the following network configuration:
# tee /etc/cni/net.d/multus-cni.conf <<-'EOF'
{
"name": "multus-demo-network",
"type": "multus",
"delegates": [
{
"type": "sriov",
#part of sriov plugin conf
"if0": "enp12s0f0",
"ipam": {
"type": "host-local",
"subnet": "10.56.217.0/24",
"rangeStart": "10.56.217.131",
"rangeEnd": "10.56.217.190",
"routes": [
{ "dst": "0.0.0.0/0" }
],
"gateway": "10.56.217.1"
}
},
{
"type": "ptp",
"ipam": {
"type": "host-local",
"subnet": "10.168.1.0/24",
"rangeStart": "10.168.1.11",
"rangeEnd": "10.168.1.20",
"routes": [
{ "dst": "0.0.0.0/0" }
],
"gateway": "10.168.1.1"
}
},
{
"type": "flannel",
"delegate": {
"isDefaultGateway": true
}
}
]
}
EOF
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.
Multus will always log via STDERR, which is the standard method by which CNI plugins communicate errors, and these errors are logged by the Kubelet. This method is always enabled.
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:
"LogFile": "/var/log/multus.log",
The default logging level is set as panic -- this will log only the most critical errors, and is the least verbose logging level.
The available logging level values, in decreasing order of verbosity are:
debugerrorpanic
You may configure the logging level by using the LogLevel option in your CNI configuration. For example:
"LogLevel": "debug",
Github user YYGCui has used multiple flannel network to work with Multus CNI plugin. Please refer to this closed issue for ,multiple overlay network support with Multus CNI.
Make sure that the multus, sriov, flannel, and ptp binaries are in the /opt/cni/bin directories and follow the steps as mentioned in the CNI
Kubelet must be configured to run with the CNI network plugin. Edit /etc/kubernetes/kubelet file and add --network-plugin=cni flags in KUBELET\_OPTS as shown below:
KUBELET_OPTS="...
--network-plugin-dir=/etc/cni/net.d
--network-plugin=cni
"
Refer to the Kubernetes User Guide and network plugin for more information.
With Multus CNI configured as described in sections above each workload launched via a Kubernetes Pod will have multiple network interfacesLaunch the workload using yaml file in the kubernetes master, with above configuration in the multus CNI, each pod should have multiple interfaces.
Note: To verify whether Multus CNI plugin is working correctly, create a pod containing one busybox container and execute ip link command to check if interfaces management follows configuration.
- Create
multus-test.yamlfile containing below configuration. Created pod will consist of onebusyboxcontainer runningtopcommand.
apiVersion: v1
kind: Pod
metadata:
name: multus-test
spec: # specification of the pod's contents
restartPolicy: Never
containers:
- name: test1
image: "busybox"
command: ["top"]
stdin: true
tty: true
- Create pod using command:
# kubectl create -f multus-test.yaml
pod "multus-test" created
- Run "ip link" command inside the container:
# 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
3: eth0@if41: <BROADCAST,MULTICAST,UP,LOWER_UP,M-DOWN> mtu 1500 qdisc noqueue
link/ether 26:52:6b:d8:44:2d brd ff:ff:ff:ff:ff:ff
20: net0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq qlen 1000
link/ether f6:fb:21:4f:1d:63 brd ff:ff:ff:ff:ff:ff
21: net1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq qlen 1000
link/ether 76:13:b1:60:00:00 brd ff:ff:ff:ff:ff:ff
| Interface name | Description |
|---|---|
| lo | loopback |
| eth0@if41 | Flannel network tap interface |
| net0 | VF assigned to the container by SR-IOV CNI plugin |
| net1 | ptp localhost interface |
- DPDK-SRIOV CNI
- Vhostuser CNI - a Dataplane network plugin - Supports OVS-DPDK & VPP
- Bond CNI - For fail-over and high availability of networking
- KubeCon workshop on "Enabling NFV features in Kubernetes" presentation slide deck
- Feature brief
- Application note
- White paper
- Multus's related project github pages
- Read Containers Experience Kits
- Try our container exp kit demo - KubeCon workshop on Enabling NFV Features in Kubernetes
- Join us on #intel-sddsg-slack slack channel and ask question in #general-discussion
- You can also email us
- Feel free to submit an issue
Please fill in the Questions/feedback - google-form!
For any questions about Multus CNI, please reach out on github issue or feel free to contact the developer @kural in our Intel-Corp Slack