$ openstack subnet set --dns-nameserver 0.0.0.0 <subnet_id>
As a cluster administrator, you can configure an additional network for your cluster. The following network types are supported:
You can manage the life cycle of an additional network by two approaches. Each approach is mutually exclusive and you can only use one approach for managing an additional network at a time. For either approach, the additional network is managed by a Container Network Interface (CNI) plugin that you configure.
For an additional network, IP addresses are provisioned through an IP Address Management (IPAM) CNI plugin that you configure as part of the additional network. The IPAM plugin supports a variety of IP address assignment approaches including DHCP and static assignment.
Modify the Cluster Network Operator (CNO) configuration: The CNO automatically creates and manages the NetworkAttachmentDefinition
object. In addition to managing the object lifecycle the CNO ensures a DHCP is available for an additional network that uses a DHCP assigned IP address.
Applying a YAML manifest: You can manage the additional network directly by creating an NetworkAttachmentDefinition
object. This approach allows for the chaining of CNI plugins.
When deploying OpenShift Container Platform nodes with multiple network interfaces on Red Hat OpenStack Platform (RHOSP) with OVN SDN, DNS configuration of the secondary interface might take precedence over the DNS configuration of the primary interface. In this case, remove the DNS nameservers for the subnet id that is attached to the secondary interface:
|
An additional network is configured by using the NetworkAttachmentDefinition
API in the k8s.cni.cncf.io
API group.
Do not store any sensitive information or a secret in the |
The configuration for the API is described in the following table:
Field | Type | Description |
---|---|---|
|
|
The name for the additional network. |
|
|
The namespace that the object is associated with. |
|
|
The CNI plugin configuration in JSON format. |
The configuration for an additional network attachment is specified as part of the Cluster Network Operator (CNO) configuration.
The following YAML describes the configuration parameters for managing an additional network with the CNO:
apiVersion: operator.openshift.io/v1
kind: Network
metadata:
name: cluster
spec:
# ...
additionalNetworks: (1)
- name: <name> (2)
namespace: <namespace> (3)
rawCNIConfig: |- (4)
{
...
}
type: Raw
1 | An array of one or more additional network configurations. | ||
2 | The name for the additional network attachment that you are creating. The name must be unique within the specified namespace . |
||
3 | The namespace to create the network attachment in. If you do not specify a value then the default namespace is used.
|
||
4 | A CNI plugin configuration in JSON format. |
The configuration for an additional network is specified from a YAML configuration file, such as in the following example:
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
name: <name> (1)
spec:
config: |- (2)
{
...
}
1 | The name for the additional network attachment that you are creating. |
2 | A CNI plugin configuration in JSON format. |
The specific configuration fields for additional networks is described in the following sections.
The following object describes the configuration parameters for the bridge CNI plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The |
|
|
The value for the |
|
|
The name of the CNI plugin to configure: |
|
|
The configuration object for the IPAM CNI plugin. The plugin manages IP address assignment for the attachment definition. |
|
|
Optional: Specify the name of the virtual bridge to use. If the bridge interface does not exist on the host, it is created. The default value is |
|
|
Optional: Set to |
|
|
Optional: Set to |
|
|
Optional: Set to |
|
|
Optional: Set to |
|
|
Optional: Set to |
|
|
Optional: Set to |
|
|
Optional: Specify a virtual LAN (VLAN) tag as an integer value. By default, no VLAN tag is assigned. |
|
|
Optional: Indicates whether the default vlan must be preserved on the |
|
|
Optional: Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. |
|
|
Optional: Enables duplicate address detection for the container side |
|
|
Optional: Enables mac spoof check, limiting the traffic originating from the container to the mac address of the interface. The default value is |
The VLAN parameter configures the VLAN tag on the host end of the |
To configure uplink for a L2 network you need to allow the vlan on the uplink interface by using the following command:
|
Specify your network device by setting only one of the following parameters: |
The following object describes the configuration parameters for the host-device CNI plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The |
|
|
The value for the |
|
|
The name of the CNI plugin to configure: |
|
|
Optional: The name of the device, such as |
|
|
Optional: The device hardware MAC address. |
|
|
Optional: The Linux kernel device path, such as |
|
|
Optional: The PCI address of the network device, such as |
The following object describes the configuration parameters for the VLAN CNI plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The |
|
|
The value for the |
|
|
The name of the CNI plugin to configure: |
|
|
The Ethernet interface to associate with the network attachment. If a |
|
|
Set the id of the vlan. |
|
|
The configuration object for the IPAM CNI plugin. The plugin manages IP address assignment for the attachment definition. |
|
|
Optional: Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. |
|
|
Optional: DNS information to return, for example, a priority-ordered list of DNS nameservers. |
|
|
Optional: Specifies if the master interface is in the container network namespace or the main network namespace. |
The following example configures an additional network named vlan-net
:
{
"name": "vlan-net",
"cniVersion": "0.3.1",
"type": "vlan",
"master": "eth0",
"mtu": 1500,
"vlanId": 5,
"linkInContainer": false,
"ipam": {
"type": "host-local",
"subnet": "10.1.1.0/24"
},
"dns": {
"nameservers": [ "10.1.1.1", "8.8.8.8" ]
}
}
The following object describes the configuration parameters for the IPVLAN CNI plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The |
|
|
The value for the |
|
|
The name of the CNI plugin to configure: |
|
|
The configuration object for the IPAM CNI plugin. The plugin manages IP address assignment for the attachment definition. This is required unless the plugin is chained. |
|
|
Optional: The operating mode for the virtual network. The value must be |
|
|
Optional: The Ethernet interface to associate with the network attachment. If a |
|
|
Optional: Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. |
|
The following object describes the configuration parameters for the macvlan CNI plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The |
|
|
The value for the |
|
|
The name of the CNI plugin to configure: |
|
|
The configuration object for the IPAM CNI plugin. The plugin manages IP address assignment for the attachment definition. |
|
|
Optional: Configures traffic visibility on the virtual network. Must be either |
|
|
Optional: The host network interface to associate with the newly created macvlan interface. If a value is not specified, then the default route interface is used. |
|
|
Optional: The maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. |
If you specify the |
The Red Hat OpenShift Networking OVN-Kubernetes network plugin allows the configuration of secondary network interfaces for pods. To configure secondary network interfaces, you must define the configurations in the NetworkAttachmentDefinition
custom resource definition (CRD).
Configuration for an OVN-Kubernetes additional network is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope. |
Pod and multi-network policy creation might remain in a pending state until the OVN-Kubernetes control plane agent in the nodes processes the associated |
The following sections provide example configurations for each of the topologies that OVN-Kubernetes currently allows for secondary networks.
Networks names must be unique. For example, creating multiple |
The following table describes the configuration parameters for the OVN-Kubernetes CNI network plugin:
Field | Type | Description |
---|---|---|
|
|
The CNI specification version. The required value is |
|
|
The name of the network. These networks are not namespaced. For example, you can have a network named
|
|
|
The name of the CNI plugin to configure. The required value is |
|
|
The topological configuration for the network. The required value is |
|
|
The subnet to use for the network across the cluster. For |
|
|
The maximum transmission unit (MTU) to the specified value. The default value, |
|
|
The metadata |
|
|
A comma-separated list of CIDRs and IPs. IPs are removed from the assignable IP pool, and are never passed to the pods. When omitted, the logical switch implementing the network only provides layer 2 communication, and users must configure IPs for the pods. Port security only prevents MAC spoofing. |
The switched (layer 2) topology networks interconnect the workloads through a cluster-wide logical switch. This configuration can be used for IPv6 and dual-stack deployments.
Layer 2 switched topology networks only allow for the transfer of data packets between pods within a cluster. |
The following NetworkAttachmentDefinition
custom resource definition (CRD) YAML describes the fields needed to configure a switched secondary network.
{
"cniVersion": "0.3.1",
"name": "l2-network",
"type": "ovn-k8s-cni-overlay",
"topology":"layer2",
"subnets": "10.100.200.0/24",
"mtu": 1300,
"netAttachDefName": "ns1/l2-network",
"excludeSubnets": "10.100.200.0/29"
}
You must specify the secondary network attachments through the k8s.v1.cni.cncf.io/networks
annotation.
The following example provisions a pod with two secondary attachments, one for each of the attachment configurations presented in this guide.
apiVersion: v1
kind: Pod
metadata:
annotations:
k8s.v1.cni.cncf.io/networks: l2-network
name: tinypod
namespace: ns1
spec:
containers:
- args:
- pause
image: k8s.gcr.io/e2e-test-images/agnhost:2.36
imagePullPolicy: IfNotPresent
name: agnhost-container
The following example provisions a pod with a static IP address.
|
apiVersion: v1
kind: Pod
metadata:
annotations:
k8s.v1.cni.cncf.io/networks: '[
{
"name": "l2-network", (1)
"mac": "02:03:04:05:06:07", (2)
"interface": "myiface1", (3)
"ips": [
"192.0.2.20/24"
] (4)
}
]'
name: tinypod
namespace: ns1
spec:
containers:
- args:
- pause
image: k8s.gcr.io/e2e-test-images/agnhost:2.36
imagePullPolicy: IfNotPresent
name: agnhost-container
1 | The name of the network. This value must be unique across all NetworkAttachmentDefinitions . |
2 | The MAC address to be assigned for the interface. |
3 | The name of the network interface to be created for the pod. |
4 | The IP addresses to be assigned to the network interface. |
The IP address management (IPAM) Container Network Interface (CNI) plugin provides IP addresses for other CNI plugins.
You can use the following IP address assignment types:
Static assignment.
Dynamic assignment through a DHCP server. The DHCP server you specify must be reachable from the additional network.
Dynamic assignment through the Whereabouts IPAM CNI plugin.
The following table describes the configuration for static IP address assignment:
Field | Type | Description |
---|---|---|
|
|
The IPAM address type. The value |
|
|
An array of objects specifying IP addresses to assign to the virtual interface. Both IPv4 and IPv6 IP addresses are supported. |
|
|
An array of objects specifying routes to configure inside the pod. |
|
|
Optional: An array of objects specifying the DNS configuration. |
The addresses
array requires objects with the following fields:
Field | Type | Description |
---|---|---|
|
|
An IP address and network prefix that you specify. For example, if you specify |
|
|
The default gateway to route egress network traffic to. |
Field | Type | Description |
---|---|---|
|
|
The IP address range in CIDR format, such as |
|
|
The gateway where network traffic is routed. |
Field | Type | Description |
---|---|---|
|
|
An array of one or more IP addresses for to send DNS queries to. |
|
|
The default domain to append to a hostname. For example, if the
domain is set to |
|
|
An array of domain names to append to an unqualified hostname,
such as |
{
"ipam": {
"type": "static",
"addresses": [
{
"address": "191.168.1.7/24"
}
]
}
}
The following JSON describes the configuration for dynamic IP address address assignment with DHCP.
Renewal of DHCP leases
A pod obtains its original DHCP lease when it is created. The lease must be periodically renewed by a minimal DHCP server deployment running on the cluster. To trigger the deployment of the DHCP server, you must create a shim network attachment by editing the Cluster Network Operator configuration, as in the following example: Example shim network attachment definition
|
Field | Type | Description |
---|---|---|
|
|
The IPAM address type. The value |
{
"ipam": {
"type": "dhcp"
}
}
The Whereabouts CNI plugin allows the dynamic assignment of an IP address to an additional network without the use of a DHCP server.
The following table describes the configuration for dynamic IP address assignment with Whereabouts:
Field | Type | Description |
---|---|---|
|
|
The IPAM address type. The value |
|
|
An IP address and range in CIDR notation. IP addresses are assigned from within this range of addresses. |
|
|
Optional: A list of zero or more IP addresses and ranges in CIDR notation. IP addresses within an excluded address range are not assigned. |
{
"ipam": {
"type": "whereabouts",
"range": "192.0.2.192/27",
"exclude": [
"192.0.2.192/30",
"192.0.2.196/32"
]
}
}
The Whereabouts reconciler is responsible for managing dynamic IP address assignments for the pods within a cluster by using the Whereabouts IP Address Management (IPAM) solution. It ensures that each pod gets a unique IP address from the specified IP address range. It also handles IP address releases when pods are deleted or scaled down.
You can also use a |
The whereabouts-reconciler
daemon set is automatically created when you configure an additional network through the Cluster Network Operator. It is not automatically created when you configure an additional network from a YAML manifest.
To trigger the deployment of the whereabouts-reconciler
daemon set, you must manually create a whereabouts-shim
network attachment by editing the Cluster Network Operator custom resource (CR) file.
Use the following procedure to deploy the whereabouts-reconciler
daemon set.
Edit the Network.operator.openshift.io
custom resource (CR) by running the following command:
$ oc edit network.operator.openshift.io cluster
Include the additionalNetworks
section shown in this example YAML extract within the spec
definition of the custom resource (CR):
apiVersion: operator.openshift.io/v1
kind: Network
metadata:
name: cluster
# ...
spec:
additionalNetworks:
- name: whereabouts-shim
namespace: default
rawCNIConfig: |-
{
"name": "whereabouts-shim",
"cniVersion": "0.3.1",
"type": "bridge",
"ipam": {
"type": "whereabouts"
}
}
type: Raw
# ...
Save the file and exit the text editor.
Verify that the whereabouts-reconciler
daemon set deployed successfully by running the following command:
$ oc get all -n openshift-multus | grep whereabouts-reconciler
pod/whereabouts-reconciler-jnp6g 1/1 Running 0 6s
pod/whereabouts-reconciler-k76gg 1/1 Running 0 6s
pod/whereabouts-reconciler-k86t9 1/1 Running 0 6s
pod/whereabouts-reconciler-p4sxw 1/1 Running 0 6s
pod/whereabouts-reconciler-rvfdv 1/1 Running 0 6s
pod/whereabouts-reconciler-svzw9 1/1 Running 0 6s
daemonset.apps/whereabouts-reconciler 6 6 6 6 6 kubernetes.io/os=linux 6s
The Whereabouts IPAM CNI plugin runs the IP reconciler daily. This process cleans up any stranded IP allocations that might result in exhausting IPs and therefore prevent new pods from getting an IP allocated to them.
Use this procedure to change the frequency at which the IP reconciler runs.
You installed the OpenShift CLI (oc
).
You have access to the cluster as a user with the cluster-admin
role.
You have deployed the whereabouts-reconciler
daemon set, and the whereabouts-reconciler
pods are up and running.
Run the following command to create a ConfigMap
object named whereabouts-config
in the openshift-multus
namespace with a specific cron expression for the IP reconciler:
$ oc create configmap whereabouts-config -n openshift-multus --from-literal=reconciler_cron_expression="*/15 * * * *"
This cron expression indicates the IP reconciler runs every 15 minutes. Adjust the expression based on your specific requirements.
The |
Retrieve information about resources related to the whereabouts-reconciler
daemon set and pods within the openshift-multus
namespace by running the following command:
$ oc get all -n openshift-multus | grep whereabouts-reconciler
pod/whereabouts-reconciler-2p7hw 1/1 Running 0 4m14s
pod/whereabouts-reconciler-76jk7 1/1 Running 0 4m14s
pod/whereabouts-reconciler-94zw6 1/1 Running 0 4m14s
pod/whereabouts-reconciler-mfh68 1/1 Running 0 4m14s
pod/whereabouts-reconciler-pgshz 1/1 Running 0 4m14s
pod/whereabouts-reconciler-xn5xz 1/1 Running 0 4m14s
daemonset.apps/whereabouts-reconciler 6 6 6 6 6 kubernetes.io/os=linux 4m16s
Run the following command to verify that the whereabouts-reconciler
pod runs the IP reconciler with the configured interval:
$ oc -n openshift-multus logs whereabouts-reconciler-2p7hw
2024-02-02T16:33:54Z [debug] event not relevant: "/cron-schedule/..2024_02_02_16_33_54.1375928161": CREATE
2024-02-02T16:33:54Z [debug] event not relevant: "/cron-schedule/..2024_02_02_16_33_54.1375928161": CHMOD
2024-02-02T16:33:54Z [debug] event not relevant: "/cron-schedule/..data_tmp": RENAME
2024-02-02T16:33:54Z [verbose] using expression: */15 * * * *
2024-02-02T16:33:54Z [verbose] configuration updated to file "/cron-schedule/..data". New cron expression: */15 * * * *
2024-02-02T16:33:54Z [verbose] successfully updated CRON configuration id "00c2d1c9-631d-403f-bb86-73ad104a6817" - new cron expression: */15 * * * *
2024-02-02T16:33:54Z [debug] event not relevant: "/cron-schedule/config": CREATE
2024-02-02T16:33:54Z [debug] event not relevant: "/cron-schedule/..2024_02_02_16_26_17.3874177937": REMOVE
2024-02-02T16:45:00Z [verbose] starting reconciler run
2024-02-02T16:45:00Z [debug] NewReconcileLooper - inferred connection data
2024-02-02T16:45:00Z [debug] listing IP pools
2024-02-02T16:45:00Z [debug] no IP addresses to cleanup
2024-02-02T16:45:00Z [verbose] reconciler success
The Cluster Network Operator (CNO) manages additional network definitions. When
you specify an additional network to create, the CNO creates the
NetworkAttachmentDefinition
object automatically.
Do not edit the |
Install the OpenShift CLI (oc
).
Log in as a user with cluster-admin
privileges.
Optional: Create the namespace for the additional networks:
$ oc create namespace <namespace_name>
To edit the CNO configuration, enter the following command:
$ oc edit networks.operator.openshift.io cluster
Modify the CR that you are creating by adding the configuration for the additional network that you are creating, as in the following example CR.
apiVersion: operator.openshift.io/v1
kind: Network
metadata:
name: cluster
spec:
# ...
additionalNetworks:
- name: tertiary-net
namespace: namespace2
type: Raw
rawCNIConfig: |-
{
"cniVersion": "0.3.1",
"name": "tertiary-net",
"type": "ipvlan",
"master": "eth1",
"mode": "l2",
"ipam": {
"type": "static",
"addresses": [
{
"address": "192.168.1.23/24"
}
]
}
}
Save your changes and quit the text editor to commit your changes.
Confirm that the CNO created the NetworkAttachmentDefinition
object by running the following command. There might be a delay before the CNO creates the object.
$ oc get network-attachment-definitions -n <namespace>
where:
<namespace>
Specifies the namespace for the network attachment that you added to the CNO configuration.
NAME AGE
test-network-1 14m
Install the OpenShift CLI (oc
).
Log in as a user with cluster-admin
privileges.
Create a YAML file with your additional network configuration, such as in the following example:
apiVersion: k8s.cni.cncf.io/v1
kind: NetworkAttachmentDefinition
metadata:
name: next-net
spec:
config: |-
{
"cniVersion": "0.3.1",
"name": "work-network",
"type": "host-device",
"device": "eth1",
"ipam": {
"type": "dhcp"
}
}
To create the additional network, enter the following command:
$ oc apply -f <file>.yaml
where:
<file>
Specifies the name of the file contained the YAML manifest.