Network (Neutron)

Neutron is the Network service for OpenStack. Unlike Nova Networking, Neutron allows you to configure advanced virtual network topologies. An example of this is per-tenant private networks.

Neutron is broken up into the following abstractions: Networks, Subnets and Routers. Each has functionality that mimics the physical layers.

Networks

A network represents a slice of the outside network. Networks contain subnets, and routers to route traffic between different subnets and networks.

Create a Network

Network network = os.networking().network()
        .create(Builders.network().name("ext_network").tenantId(tenant.getId()).build());

Network network = os.networking().network()
        .create(Builders.network().name("ext_network").tenantId(tenant.getId()).build());

Querying for Networks

// List the networks which the current tenant has access to
List<? extends Network> networks = os.networking().network().list();
    
// Get a network by ID
Network network = os.networking().network().get("networkId");

Delete a Network

os.networking().network().delete("networkId");

Subnets

A subnet is a subdivision of an IP Network. The examples below will cover basic subnet management and how we leverage them using OpenStack4j.

Create a Subnet

Subnet subnet = os.networking().subnet().create(Builders.subnet()
        .name("MySubnet")
        .networkId("networkId")
        .tenantId("tenantId")
        .addPool("192.168.0.1", "192.168.0.254")
        .ipVersion(IPVersionType.V4)
        .cidr("192.168.0.0/24")
        .build());

Querying for Subnets

// List all subnets which the current authorized tenant has access to
List<? extends Subnet> subnets = os.networking().subnet().list();

// Get a Subnet by ID
Subnet subnet = os.networking().subnet().get("subnetId");

Delete a Subnet

os.networking().subnet().delete("subnetId");

Ports

A port is exactly what you think it is. It mimics a physical port which is tied to a network and can be allocated a fixed ip from a subnet.

Create a Port

In the example below we will create a new port and assign it a fixed IP Address from the subnet we defined in the above examples.

Port port = os.networking().port().create(Builders.port()
        .name("port-1")
        .networkId("networkId")
        .fixedIp("192.168.0.101", "subnetId")
        .build());

Updating the Port

Port updatedPort = os.networking().port().update(port.builder().name("port-1-1").build());

Querying for Ports

// List all Ports which the current authorized tenant has access to
List<? extends Port> ports = os.networking().port().list();

// Get a Port by ID
Port port = os.networking().port().get("portId");

Delete a Port

os.networking().port().delete("portId");

Routers

For outside networks to access VMs, routers between subnets are needed. Each router has one gateway that is connected to a network and many interfaces that are connected to various subnets. Like a real world physical router, subnets can access machines on other subnets that are connected to the same router. More information about routers can be found at Neutron Concepts

Create a Router

Router router = os.networking().router().create(Builders.router()
        .name("ext_net")
        .adminStateUp(true)
        .externalGateway("networkId")
        .route("192.168.0.0/24", "10.20.20.1")
        .build());

Update a Router

router = os.networking().router().update(router.toBuilder().name("ext_net2").build());

Toggle Administrative State

Router router = os.networking().router().toggleAdminStateUp("routerId", true);

Attaching / Detaching External Interfaces

// Attach an External Interface
RouterInterface iface = os.networking().router()
        .attachInterface("routerId", AttachInterfaceType.SUBNET, "subnetId");

// Detach an External Interface
RouterInterface iface = os.networking().router()
        .detachInterface("routerId", "subnetId", null);

Delete a Router

os.networking().router().delete("routerId");

Querying for Routers

List<Router> = os.networking().router().list();

// Get a Router by ID
Router router = os.networking().router().get("routerId");

Floating IP addresses

Floating IPs makes services from internal networks available in an external network.

Creating and attaching Floating IPs

A Floating IP address can be created and associated with server atomically.

// Identify server port based on the server ID and the private network
Port port = os.networking().port().list(
        PortListOptions.create().deviceId(server.getId()).networkId("private-network-id")
).get(0);

// Create floating IP in the public network
NetFloatingIP fip = Builders.netFloatingIP().portId(port.getId()).floatingNetworkId("public-network-id").build();
fip = os.networking().floatingip().create(fip);

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