Networking Config Version 1

This network configuration format lets users customize their instance’s networking interfaces by assigning subnet configuration, virtual device creation (bonds, bridges, vlans) routes and DNS configuration.

Required elements of a Network Config Version 1 are config and version.

Cloud-init will read this format from system config. For example the following could be present in /etc/cloud/cloud.cfg.d/custom-networking.cfg:

network:
  version: 1
  config:
  - type: physical
    name: eth0
    subnets:
      - type: dhcp

The NoCloud datasource can also provide cloud-init networking configuration in this Format.

Configuration Types

Within the network config portion, users include a list of configuration types. The current list of support type values are as follows:

  • Physical (physical)
  • Bond (bond)
  • Bridge (bridge)
  • VLAN (vlan)
  • Nameserver (nameserver)
  • Route (route)

Physical, Bond, Bridge and VLAN types may also include IP configuration under the key subnets.

  • Subnet/IP (subnets)

Physical

The physical type configuration represents a “physical” network device, typically Ethernet-based. At least one of of these entries is required for external network connectivity. Type physical requires only one key: name. A physical device may contain some or all of the following keys:

name: <desired device name>

A devices name must be less than 15 characters. Names exceeding the maximum will be truncated. This is a limitation of the Linux kernel network-device structure.

mac_address: <MAC Address>

The MAC Address is a device unique identifier that most Ethernet-based network devices possess. Specifying a MAC Address is optional. Letters must be lowercase.

Note

MAC addresses must be strings. As MAC addresses which consist of only the digits 0-9 (i.e. no hex a-f) can be interpreted as a base 60 integer per the YAML 1.1 spec it is best practice to quote all MAC addresses to ensure they are parsed as strings regardless of value.

Note

Cloud-init will handle the persistent mapping between a device’s name and the mac_address.

mtu: <MTU SizeBytes>

The MTU key represents a device’s Maximum Transmission Unit, the largest size packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network. Specifying mtu is optional.

Note

The possible supported values of a device’s MTU is not available at configuration time. It’s possible to specify a value too large or to small for a device and may be ignored by the device.

Physical Example:

network:
  version: 1
  config:
    # Simple network adapter
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
    # Second nic with Jumbo frames
    - type: physical
      name: jumbo0
      mac_address: aa:11:22:33:44:55
      mtu: 9000
    # 10G pair
    - type: physical
      name: gbe0
      mac_address: cd:11:22:33:44:00
    - type: physical
      name: gbe1
      mac_address: cd:11:22:33:44:02

Bond

A bond type will configure a Linux software Bond with one or more network devices. A bond type requires the following keys:

name: <desired device name>

A devices name must be less than 15 characters. Names exceeding the maximum will be truncated. This is a limitation of the Linux kernel network-device structure.

mac_address: <MAC Address>

When specifying MAC Address on a bond this value will be assigned to the bond device and may be different than the MAC address of any of the underlying bond interfaces. Specifying a MAC Address is optional. If mac_address is not present, then the bond will use one of the MAC Address values from one of the bond interfaces.

Note

MAC addresses must be strings. As MAC addresses which consist of only the digits 0-9 (i.e. no hex a-f) can be interpreted as a base 60 integer per the YAML 1.1 spec it is best practice to quote all MAC addresses to ensure they are parsed as strings regardless of value.

bond_interfaces: <List of network device names>

The bond_interfaces key accepts a list of network device name values from the configuration. This list may be empty.

mtu: <MTU SizeBytes>

The MTU key represents a device’s Maximum Transmission Unit, the largest size packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network. Specifying mtu is optional.

Note

The possible supported values of a device’s MTU is not available at configuration time. It’s possible to specify a value too large or to small for a device and may be ignored by the device.

params: <Dictionary of key: value bonding parameter pairs>

The params key in a bond holds a dictionary of bonding parameters. This dictionary may be empty. For more details on what the various bonding parameters mean please read the Linux Kernel Bonding.txt.

Valid params keys are:

  • active_slave: Set bond attribute
  • ad_actor_key: Set bond attribute
  • ad_actor_sys_prio: Set bond attribute
  • ad_actor_system: Set bond attribute
  • ad_aggregator: Set bond attribute
  • ad_num_ports: Set bond attribute
  • ad_partner_key: Set bond attribute
  • ad_partner_mac: Set bond attribute
  • ad_select: Set bond attribute
  • ad_user_port_key: Set bond attribute
  • all_slaves_active: Set bond attribute
  • arp_all_targets: Set bond attribute
  • arp_interval: Set bond attribute
  • arp_ip_target: Set bond attribute
  • arp_validate: Set bond attribute
  • downdelay: Set bond attribute
  • fail_over_mac: Set bond attribute
  • lacp_rate: Set bond attribute
  • lp_interval: Set bond attribute
  • miimon: Set bond attribute
  • mii_status: Set bond attribute
  • min_links: Set bond attribute
  • mode: Set bond attribute
  • num_grat_arp: Set bond attribute
  • num_unsol_na: Set bond attribute
  • packets_per_slave: Set bond attribute
  • primary: Set bond attribute
  • primary_reselect: Set bond attribute
  • queue_id: Set bond attribute
  • resend_igmp: Set bond attribute
  • slaves: Set bond attribute
  • tlb_dynamic_lb: Set bond attribute
  • updelay: Set bond attribute
  • use_carrier: Set bond attribute
  • xmit_hash_policy: Set bond attribute

Bond Example:

network:
 version: 1
 config:
   # Simple network adapter
   - type: physical
     name: interface0
     mac_address: '00:11:22:33:44:55'
   # 10G pair
   - type: physical
     name: gbe0
     mac_address: cd:11:22:33:44:00
   - type: physical
     name: gbe1
     mac_address: cd:11:22:33:44:02
   - type: bond
     name: bond0
     bond_interfaces:
       - gbe0
       - gbe1
     params:
       bond-mode: active-backup

Bridge

Type bridge requires the following keys:

  • name: Set the name of the bridge.
  • bridge_interfaces: Specify the ports of a bridge via their name. This list may be empty.
  • params: A list of bridge params. For more details, please read the bridge-utils-interfaces manpage.

Valid keys are:

  • bridge_ageing: Set the bridge’s ageing value.
  • bridge_bridgeprio: Set the bridge device network priority.
  • bridge_fd: Set the bridge’s forward delay.
  • bridge_hello: Set the bridge’s hello value.
  • bridge_hw: Set the bridge’s MAC address.
  • bridge_maxage: Set the bridge’s maxage value.
  • bridge_maxwait: Set how long network scripts should wait for the bridge to be up.
  • bridge_pathcost: Set the cost of a specific port on the bridge.
  • bridge_portprio: Set the priority of a specific port on the bridge.
  • bridge_ports: List of devices that are part of the bridge.
  • bridge_stp: Set spanning tree protocol on or off.
  • bridge_waitport: Set amount of time in seconds to wait on specific ports to become available.

Bridge Example:

network:
 version: 1
 config:
   # Simple network adapter
   - type: physical
     name: interface0
     mac_address: '00:11:22:33:44:55'
   # Second nic with Jumbo frames
   - type: physical
     name: jumbo0
     mac_address: aa:11:22:33:44:55
     mtu: 9000
   - type: bridge
     name: br0
     bridge_interfaces:
       - jumbo0
     params:
       bridge_ageing: 250
       bridge_bridgeprio: 22
       bridge_fd: 1
       bridge_hello: 1
       bridge_maxage: 10
       bridge_maxwait: 0
       bridge_pathcost:
         - jumbo0 75
       bridge_pathprio:
         - jumbo0 28
       bridge_stp: 'off'
       bridge_maxwait:
         - jumbo0 0

VLAN

Type vlan requires the following keys:

  • name: Set the name of the VLAN
  • vlan_link: Specify the underlying link via its name.
  • vlan_id: Specify the VLAN numeric id.

The following optional keys are supported:

mtu: <MTU SizeBytes>

The MTU key represents a device’s Maximum Transmission Unit, the largest size packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network. Specifying mtu is optional.

Note

The possible supported values of a device’s MTU is not available at configuration time. It’s possible to specify a value too large or to small for a device and may be ignored by the device.

VLAN Example:

network:
  version: 1
  config:
    # Physical interfaces.
    - type: physical
      name: eth0
      mac_address: c0:d6:9f:2c:e8:80
    # VLAN interface.
    - type: vlan
      name: eth0.101
      vlan_link: eth0
      vlan_id: 101
      mtu: 1500

Nameserver

Users can specify a nameserver type. Nameserver dictionaries include the following keys:

  • address: List of IPv4 or IPv6 address of nameservers.
  • search: List of of hostnames to include in the resolv.conf search path.
  • interface: Optional. Ties the nameserver definition to the specified interface. The value specified here must match the name of an interface defined in this config. If unspecified, this nameserver will be considered a global nameserver.

Nameserver Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
         - type: static
           address: 192.168.23.14/27
           gateway: 192.168.23.1
    - type: nameserver
      interface: interface0  # Ties nameserver to interface0 only
      address:
        - 192.168.23.2
        - 8.8.8.8
      search:
        - exemplary

Route

Users can include static routing information as well. A route dictionary has the following keys:

  • destination: IPv4 network address with CIDR netmask notation.
  • gateway: IPv4 gateway address with CIDR netmask notation.
  • metric: Integer which sets the network metric value for this route.

Route Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
         - type: static
           address: 192.168.23.14/24
           gateway: 192.168.23.1
    - type: route
      destination: 192.168.24.0/24
      gateway: 192.168.24.1
      metric: 3

Subnet/IP

For any network device (one of the Config Types) users can define a list of subnets which contain ip configuration dictionaries. Multiple subnet entries will create interface alias allowing a single interface to use different ip configurations.

Valid keys for subnets include the following:

  • type: Specify the subnet type.
  • control: Specify manual, auto or hotplug. Indicates how the interface will be handled during boot.
  • address: IPv4 or IPv6 address. It may include CIDR netmask notation.
  • netmask: IPv4 subnet mask in dotted format or CIDR notation.
  • gateway: IPv4 address of the default gateway for this subnet.
  • dns_nameservers: Specify a list of IPv4 dns server IPs to end up in resolv.conf.
  • dns_search: Specify a list of search paths to be included in resolv.conf.
  • routes: Specify a list of routes for a given interface

Subnet types are one of the following:

  • dhcp4: Configure this interface with IPv4 dhcp.
  • dhcp: Alias for dhcp4
  • dhcp6: Configure this interface with IPv6 dhcp.
  • static: Configure this interface with a static IPv4.
  • static6: Configure this interface with a static IPv6 .
  • ipv6_dhcpv6-stateful: Configure this interface with dhcp6
  • ipv6_dhcpv6-stateless: Configure this interface with SLAAC and DHCP
  • ipv6_slaac: Configure address with SLAAC

When making use of dhcp or either of the ipv6_dhcpv6 types, no additional configuration is needed in the subnet dictionary.

Using ipv6_dhcpv6-stateless or ipv6_slaac allows the IPv6 address to be automatically configured with StateLess Address AutoConfiguration (SLAAC). SLAAC requires support from the network, so verify that your cloud or network offering has support before trying it out. With ipv6_dhcpv6-stateless, DHCPv6 is still used to fetch other subnet details such as gateway or DNS servers. If you only want to discover the address, use ipv6_slaac.

Subnet DHCP Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
        - type: dhcp

Subnet Static Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
        - type: static
          address: 192.168.23.14/27
          gateway: 192.168.23.1
          dns_nameservers:
            - 192.168.23.2
            - 8.8.8.8
          dns_search:
            - exemplary.maas

The following will result in an interface0 using DHCP and interface0:1 using the static subnet configuration.

Multiple subnet Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
        - type: dhcp
        - type: static
          address: 192.168.23.14/27
          gateway: 192.168.23.1
          dns_nameservers:
            - 192.168.23.2
            - 8.8.8.8
          dns_search:
            - exemplary

Subnet with routes Example:

network:
  version: 1
  config:
    - type: physical
      name: interface0
      mac_address: '00:11:22:33:44:55'
      subnets:
        - type: dhcp
        - type: static
          address: 10.184.225.122
          netmask: 255.255.255.252
          routes:
            - gateway: 10.184.225.121
              netmask: 255.240.0.0
              network: 10.176.0.0
            - gateway: 10.184.225.121
              netmask: 255.240.0.0
              network: 10.208.0.0

Multi-layered configurations

Complex networking sometimes uses layers of configuration. The syntax allows users to build those layers one at a time. All of the virtual network devices supported allow specifying an underlying device by their name value.

Bonded VLAN Example:

network:
  version: 1
  config:
    # 10G pair
    - type: physical
      name: gbe0
      mac_address: cd:11:22:33:44:00
    - type: physical
      name: gbe1
      mac_address: cd:11:22:33:44:02
    # Bond.
    - type: bond
      name: bond0
      bond_interfaces:
        - gbe0
        - gbe1
      params:
        bond-mode: 802.3ad
        bond-lacp-rate: fast
    # A Bond VLAN.
    - type: vlan
        name: bond0.200
        vlan_link: bond0
        vlan_id: 200
        subnets:
            - type: dhcp4

More Examples

Some more examples to explore the various options available.

Multiple VLAN example:

network:
  version: 1
  config:
  - id: eth0
    mac_address: d4:be:d9:a8:49:13
    mtu: 1500
    name: eth0
    subnets:
    - address: 10.245.168.16/21
      dns_nameservers:
      - 10.245.168.2
      gateway: 10.245.168.1
      type: static
    type: physical
  - id: eth1
    mac_address: d4:be:d9:a8:49:15
    mtu: 1500
    name: eth1
    subnets:
    - address: 10.245.188.2/24
      dns_nameservers: []
      type: static
    type: physical
  - id: eth1.2667
    mtu: 1500
    name: eth1.2667
    subnets:
    - address: 10.245.184.2/24
      dns_nameservers: []
      type: static
    type: vlan
    vlan_id: 2667
    vlan_link: eth1
  - id: eth1.2668
    mtu: 1500
    name: eth1.2668
    subnets:
    - address: 10.245.185.1/24
      dns_nameservers: []
      type: static
    type: vlan
    vlan_id: 2668
    vlan_link: eth1
  - id: eth1.2669
    mtu: 1500
    name: eth1.2669
    subnets:
    - address: 10.245.186.1/24
      dns_nameservers: []
      type: static
    type: vlan
    vlan_id: 2669
    vlan_link: eth1
  - id: eth1.2670
    mtu: 1500
    name: eth1.2670
    subnets:
    - address: 10.245.187.2/24
      dns_nameservers: []
      type: static
    type: vlan
    vlan_id: 2670
    vlan_link: eth1
  - address: 10.245.168.2
    search:
    - dellstack
    type: nameserver