Create subnets¶

Before creating an L2 template, ensure that you have the required subnets that can be used in the L2 template to allocate IP addresses for the managed cluster nodes. Where required, create a number of subnets for a particular project using the Subnet CR. A subnet has three logical scopes:

• global - CR uses the default namespace. A subnet can be used for any cluster located in any project.

• namespaced - CR uses the namespace that corresponds to a particular project where managed clusters are located. A subnet can be used for any cluster located in the same project.

• cluster - CR uses the namespace where the referenced cluster is located. A subnet is only accessible to the cluster that L2Template.spec.clusterRef refers to. The Subnet objects with the cluster scope will be created for every new cluster.

You can have subnets with the same name in different projects. In this case, the subnet that has the same project as the cluster will be used. One L2 template may often reference several subnets, those subnets may have different scopes in this case.

The IP address objects (IPaddr CR) that are allocated from subnets always have the same project as their corresponding IpamHost objects, regardless of the subnet scope.

To create subnets:

1. Log in to a local machine where your management cluster kubeconfig is located and where kubectl is installed.

   Note

   The management cluster kubeconfig is created during the last stage of the management cluster bootstrap.

2. Create the subnet.yaml file with a number of global or namespaced subnets:

   kubectl --kubeconfig <pathToManagementClusterKubeconfig> apply -f <SubnetFileName.yaml>
   

   Note

   In the command above and in the steps below, substitute the parameters enclosed in angle brackets with the corresponding values.

   Example of a subnet.yaml file:

   apiVersion: ipam.mirantis.com/v1alpha1
   kind: Subnet
   metadata:
     name: demo
     namespace: demo-namespace
   spec:
     cidr: 10.11.0.0/24
     gateway: 10.11.0.9
     includeRanges:
     - 10.11.0.5-10.11.0.70
     nameservers:
     - 172.18.176.6
   

   Specification fields of the Subnet object¶

   Parameter	Description
   cidr (singular)	A valid IPv4 CIDR, for example, 10.11.0.0/24.
   includeRanges (list)	A list of IP address ranges within the given CIDR that should be used in the allocation of IPs for nodes (excluding the gateway address). The IPs outside the given ranges will not be used in the allocation. Each element of the list can be either an interval 10.11.0.5-10.11.0.70 or a single address 10.11.0.77. In the example above, the addresses 10.11.0.5-10.11.0.70 (excluding the gateway address 10.11.0.9) will be allocated for nodes. The includeRanges parameter is mutually exclusive with excludeRanges.
   excludeRanges (list)	A list of IP address ranges within the given CIDR that should not be used in the allocation of IPs for nodes. The IPs within the given CIDR but outside the given ranges will be used in the allocation (excluding gateway address). Each element of the list can be either an interval 10.11.0.5-10.11.0.70 or a single address 10.11.0.77. The excludeRanges parameter is mutually exclusive with includeRanges.
   useWholeCidr (boolean)	If set to true, the subnet address (10.11.0.0 in the example above) and the broadcast address (10.11.0.255 in the example above) are included into the address allocation for nodes. Otherwise, (false by default), the subnet address and broadcast address will be excluded from the address allocation.
   gateway (singular)	A valid gateway address, for example, 10.11.0.9.
   nameservers (list)	A list of the IP addresses of name servers. Each element of the list is a single address, for example, 172.18.176.6.

   Caution

   The subnet for the PXE network is automatically created during deployment and must contain the ipam/DefaultSubnet: "1" label. Each bare metal region must have only one subnet with this label.

   The following labels in metadata describe or change the subnet functioning:

   metadata.labels fields of the Subnet object¶

   Parameter	Description
   ipam/ClusterID (singular)	UID of the cluster that the subnet belongs to. In most cases, this label is automatically set by the kaas-ipam controller and must not be manually changed, unless you create a subnet with the ipam/SVC-MetalLB label.
   ipam/SVC-MetalLB (singular) Available since 2.5.0, Technology Preview	When set to "1", the subnet provides additional address ranges for MetalLB. No IP address objects (IPaddr CR) will be generated using this subnet. When using this label, set the ipam/ClusterID label to UID of the target cluster during the subnet creation to provide additional address ranges for MetalLB using the subnet. Caution Using of a dedicated network for Kubernetes pods traffic and using of a dedicated network for external connection to the Kubernetes services exposed by the cluster described above are available as Technology Preview. Use such configurations for testing and evaluation purposes only. For details about the Mirantis Technology Preview support scope, see the Preface section of this guide. The following feature is still under development and will be announced in one of the following Container Cloud releases: Switching Kubernetes API to listen to the specified IP address on the node

3. Verify that the subnet is successfully created:

   kubectl get subnet kaas-mgmt -oyaml
   

   In the system output, verify the status fields of the subnet.yaml file using the table below.

   Status fields of the Sunbet object¶

   Parameter	Description
   statusMessage	Contains a short state description and a more detailed one if applicable. The short status values are as follows: OK - operational. ERR - non-operational. This status has a detailed description, for example, ERR: Wrong includeRange for CIDR….
   cidr	Reflects the actual CIDR, has the same meaning as spec.cidr.
   gateway	Reflects the actual gateway, has the same meaning as spec.gateway.
   nameservers	Reflects the actual name servers, has same meaning as spec.nameservers.
   ranges	Specifies the address ranges that are calculated using the fields from spec: cidr, includeRanges, excludeRanges, gateway, useWholeCidr. These ranges are directly used for nodes IP allocation.
   lastUpdate	Includes the date and time of the latest update of the Subnet RC.
   allocatable	Includes the number of currently available IP addresses that can be allocated for nodes from the subnet.
   allocatedIPs	Specifies the list of IPv4 addresses with the corresponding IPaddr object IDs that were already allocated from the subnet.
   capacity	Contains the total number of IP addresses being held by ranges that equals to a sum of the allocatable and allocatedIPs parameters values.
   versionIpam	Contains thevVersion of the kaas-ipam component that made the latest changes to the Subnet RC.

   Example of a successfully created subnet:

   apiVersion: ipam.mirantis.com/v1alpha1
   kind: Subnet
   metadata:
     labels:
       ipam/UID: 6039758f-23ee-40ba-8c0f-61c01b0ac863
       kaas.mirantis.com/provider: baremetal
       kaas.mirantis.com/region: region-one
     name: kaas-mgmt
     namespace: default
   spec:
     cidr: 10.0.0.0/24
     excludeRanges:
     - 10.0.0.100
     - 10.0.0.101-10.0.0.120
     gateway: 10.0.0.1
     includeRanges:
     - 10.0.0.50-10.0.0.90
     nameservers:
     - 172.18.176.6
   status:
     allocatable: 38
     allocatedIPs:
     - 10.0.0.50:0b50774f-ffed-11ea-84c7-0242c0a85b02
     - 10.0.0.51:1422e651-ffed-11ea-84c7-0242c0a85b02
     - 10.0.0.52:1d19912c-ffed-11ea-84c7-0242c0a85b02
     capacity: 41
     cidr: 10.0.0.0/24
     gateway: 10.0.0.1
     lastUpdate: "2020-09-26T11:40:44Z"
     nameservers:
     - 172.18.176.6
     ranges:
     - 10.0.0.50-10.0.0.90
     statusMessage: OK
     versionIpam: v3.0.999-20200807-130909-44151f8
   

4. Proceed to creating an L2 template for one or multiple managed clusters as described in Create L2 templates.