OpenStack Subnet
Deploys an OpenStack Neutron subnet within a network, providing IP address allocation via a CIDR block with configurable gateway, DHCP, DNS, and allocation pool settings.
What Gets Created
When you deploy an OpenStackSubnet resource, OpenMCF provisions:
- Neutron Subnet — an
openstack.networking.Subnetresource with the configured CIDR, IP version, gateway, DHCP settings, DNS nameservers, allocation pools, and tags
Prerequisites
- OpenStack credentials configured via environment variables or OpenMCF provider config
- An existing Neutron network — every subnet belongs to exactly one network, referenced by
networkId
Quick Start
Create a file subnet.yaml:
apiVersion: openstack.openmcf.org/v1
kind: OpenStackSubnet
metadata:
name: my-subnet
labels:
openmcf.org/provisioner: pulumi
pulumi.openmcf.org/organization: my-org
pulumi.openmcf.org/project: my-project
pulumi.openmcf.org/stack.name: dev.OpenStackSubnet.my-subnet
spec:
networkId:
value: "<network-uuid>"
cidr: "192.168.1.0/24"
Deploy:
openmcf apply -f subnet.yaml
This creates a Neutron subnet named my-subnet on the specified network with a /24 CIDR, IPv4, DHCP enabled, and an auto-assigned gateway.
Configuration Reference
Required Fields
| Field | Type | Description | Validation |
|---|---|---|---|
networkId | StringValueOrRef | ID of the network this subnet belongs to. Can reference an OpenStackNetwork resource via valueFrom. | Required |
cidr | string | IP address range in CIDR notation (e.g., 192.168.1.0/24 or 2001:db8::/64). | Required. Must match CIDR format. |
Optional Fields
| Field | Type | Default | Description |
|---|---|---|---|
ipVersion | int32 | 4 | IP protocol version. Must be 4 (IPv4) or 6 (IPv6). |
gatewayIp | string | auto-assigned | IP address of the subnet gateway. If omitted and noGateway is false, OpenStack assigns the first usable IP. Mutually exclusive with noGateway. |
noGateway | bool | false | Disables the gateway on this subnet. Use for isolated subnets (e.g., storage networks). Mutually exclusive with gatewayIp. |
enableDhcp | bool | true | Controls whether DHCP is enabled. When enabled, OpenStack's DHCP agent assigns IPs to ports on this subnet. |
dnsNameservers | string[] | [] | DNS server IP addresses pushed to instances via DHCP. |
allocationPools | AllocationPool[] | entire CIDR | Sub-ranges of the CIDR from which IPs are allocated. Each pool has a start and end IP. If omitted, the entire CIDR minus gateway and broadcast addresses is used. |
description | string | — | Human-readable description visible in the OpenStack API and Horizon. |
tags | string[] | [] | Tags for filtering and organization in the OpenStack API. Must be unique. |
region | string | provider default | Overrides the region from the provider config for this subnet. |
AllocationPool object:
| Field | Type | Description | Validation |
|---|---|---|---|
start | string | First IP address in the allocation range (e.g., 192.168.1.100). | Required |
end | string | Last IP address in the allocation range (e.g., 192.168.1.200). | Required |
Examples
Basic Subnet
A subnet with default settings on an existing network, suitable for development environments:
apiVersion: openstack.openmcf.org/v1
kind: OpenStackSubnet
metadata:
name: dev-subnet
labels:
openmcf.org/provisioner: pulumi
pulumi.openmcf.org/organization: my-org
pulumi.openmcf.org/project: my-project
pulumi.openmcf.org/stack.name: dev.OpenStackSubnet.dev-subnet
spec:
networkId:
value: "abc12345-def6-7890-abcd-ef1234567890"
cidr: "192.168.1.0/24"
description: Development subnet
Subnet with DNS and Custom Gateway
A subnet referencing a managed OpenStackNetwork resource, with custom DNS servers and an explicit gateway:
apiVersion: openstack.openmcf.org/v1
kind: OpenStackSubnet
metadata:
name: app-subnet
labels:
openmcf.org/provisioner: pulumi
pulumi.openmcf.org/organization: my-org
pulumi.openmcf.org/project: my-project
pulumi.openmcf.org/stack.name: staging.OpenStackSubnet.app-subnet
spec:
networkId:
valueFrom:
name: app-network
cidr: "10.0.0.0/16"
gatewayIp: "10.0.0.1"
dnsNameservers:
- "8.8.8.8"
- "8.8.4.4"
tags:
- staging
- app-tier
Full-Featured Subnet with Allocation Pools
A production subnet with allocation pools to reserve IP ranges, DNS servers, tags, and a specific region:
apiVersion: openstack.openmcf.org/v1
kind: OpenStackSubnet
metadata:
name: prod-subnet
labels:
openmcf.org/provisioner: pulumi
pulumi.openmcf.org/organization: my-org
pulumi.openmcf.org/project: my-project
pulumi.openmcf.org/stack.name: prod.OpenStackSubnet.prod-subnet
spec:
networkId:
valueFrom:
name: prod-network
cidr: "10.100.0.0/16"
ipVersion: 4
gatewayIp: "10.100.0.1"
enableDhcp: true
dnsNameservers:
- "10.100.0.10"
- "8.8.8.8"
allocationPools:
- start: "10.100.1.0"
end: "10.100.127.255"
- start: "10.100.200.0"
end: "10.100.254.255"
description: Production application subnet with reserved ranges
tags:
- production
- managed
region: RegionOne
Stack Outputs
After deployment, the following outputs are available in status.outputs:
| Output | Type | Description |
|---|---|---|
subnet_id | string | UUID of the created Neutron subnet |
name | string | Name of the subnet, derived from metadata.name |
cidr | string | CIDR block of the subnet |
gateway_ip | string | Gateway IP address of the subnet (empty if noGateway was set) |
network_id | string | ID of the parent network |
region | string | OpenStack region where the subnet was created |
Related Components
- OpenStackNetwork — the parent network that this subnet belongs to
- OpenStackRouterInterface — attaches a subnet to a router for inter-network routing
- OpenStackLoadBalancer — places a load balancer VIP on a subnet
- OpenStackLoadBalancerMember — registers backend members on a subnet
- OpenStackInstance — attaches compute instances to networks via subnets
Next article
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