.. _network_config: Network configuration ********************* Default behaviour ================= ``Cloud-init`` searches for network configuration in order of increasing precedence; each item overriding the previous. - **Datasource**: For example, OpenStack may provide network config in the MetaData Service. - **System config**: A ``network:`` entry in :file:`/etc/cloud/cloud.cfg.d/*` configuration files. - **Kernel command line**: ``ip=`` or ``network-config=`` User data cannot change an instance's network configuration. In the absence of network configuration in any of the above sources, ``cloud-init`` will write out a network configuration that will issue a DHCP request on a "first" network interface. .. note:: The ``network-config`` value is expected to be a Base64 encoded YAML string in :ref:`network_config_v1` or :ref:`network_config_v2` format. Optionally, it can be compressed with ``gzip`` prior to Base64 encoding. Disabling network configuration =============================== Users may disable ``cloud-init``'s network configuration capability and rely on other methods, such as embedded configuration or other customisations. ``cloud-init`` supports the following methods for disabling ``cloud-init``. Kernel command line ------------------- ``Cloud-init`` will check for the parameter ``network-config=disabled``, which will automatically disable any network configuration. Example disabling kernel command line entry: :: network-config=disabled Cloud config ------------ In the combined ``cloud-init`` configuration dictionary, merged from :file:`/etc/cloud/cloud.cfg` and :file:`/etc/cloud/cloud.cfg.d/*`: :: network: config: disabled If ``cloud-init``'s networking config has not been disabled, and no other network information is found, then it will proceed to generate a fallback networking configuration. Disabling network activation ============================ Some datasources may not be initialised until after the network has been brought up. In this case, ``cloud-init`` will attempt to bring up the interfaces specified by the datasource metadata using a network activator discovered by `cloudinit.net.activators.select_activator`_. This behaviour can be disabled in the ``cloud-init`` configuration dictionary, merged from :file:`/etc/cloud/cloud.cfg` and :file:`/etc/cloud/cloud.cfg.d/*`: :: disable_network_activation: true Fallback network configuration ============================== ``Cloud-init`` will attempt to determine which, of any attached network devices, is most likely to have a connection and then generate a network configuration to issue a DHCP request on that interface. ``Cloud-init`` runs during early boot and does not expect composed network devices (such as Bridges) to be available. ``Cloud-init`` does not consider the following interface devices as likely "first" network interfaces for fallback configuration; they are filtered out from being selected. - **loopback**: ``name=lo`` - **Virtual Ethernet**: ``name=veth*`` - **Software Bridges**: ``type=bridge`` - **Software VLANs**: ``type=vlan`` ``Cloud-init`` will prefer network interfaces that indicate they are connected via the Linux ``carrier`` flag being set. If no interfaces are marked as connected, then all unfiltered interfaces are potential connections. Of the potential interfaces, ``cloud-init`` will attempt to pick the "right" interface given the information it has available. Finally, after selecting the "right" interface, a configuration is generated and applied to the system. .. note:: PhotonOS disables fallback networking configuration by default, leaving network unrendered when no other network config is provided. If fallback config is still desired on PhotonOS, it can be enabled by providing ``disable_fallback_netcfg: false`` in :file:`/etc/cloud/cloud.cfg:sys_config` settings. Network configuration sources ============================= ``Cloud-init`` accepts a number of different network configuration formats in support of different cloud substrates. The datasource for these clouds in ``cloud-init`` will detect and consume datasource-specific network configuration formats for use when writing an instance's network configuration. The following datasources optionally provide network configuration: - :ref:`datasource_config_drive` - `OpenStack Metadata Service Network`_ - :ref:`network_config_eni` - :ref:`datasource_digital_ocean` - `DigitalOcean JSON metadata`_ - :ref:`datasource_lxd` - `LXD`_ - :ref:`datasource_nocloud` - :ref:`network_config_v1` - :ref:`network_config_v2` - :ref:`network_config_eni` - :ref:`datasource_opennebula` - :ref:`network_config_eni` - :ref:`datasource_openstack` - :ref:`network_config_eni` - `OpenStack Metadata Service Network`_ - :ref:`datasource_smartos` - `SmartOS JSON Metadata`_ - :ref:`datasource_upcloud` - `UpCloud JSON metadata`_ - :ref:`datasource_vultr` - `Vultr JSON metadata`_ For more information on network configuration formats: .. toctree:: :maxdepth: 1 network-config-format-eni.rst network-config-format-v1.rst network-config-format-v2.rst Network configuration outputs ============================= ``Cloud-init`` converts various forms of user-supplied or automatically generated configuration into an internal network configuration state. From this state, ``cloud-init`` delegates rendering of the configuration to distro-supported formats. The following ``renderers`` are supported in ``cloud-init``: NetworkManager -------------- `NetworkManager`_ is the standard Linux network configuration tool suite. It supports a wide range of networking setups. Configuration is typically stored in :file:`/etc/NetworkManager`. It is the default for a number of Linux distributions; notably Fedora, CentOS/RHEL, and their derivatives. ENI --- :file:`/etc/network/interfaces` or ``ENI`` is supported by the ``ifupdown`` package found in Alpine Linux, Debian and Ubuntu. Netplan ------- Introduced in Ubuntu 16.10 (Yakkety Yak), `Netplan`_ has been the default network configuration tool in Ubuntu since 17.10 (Artful Aardvark). Netplan consumes :ref:`network_config_v2` input and renders network configuration for supported backends such as ``systemd-networkd`` and ``NetworkManager``. Sysconfig --------- Sysconfig format is used by RHEL, CentOS, Fedora and other derivatives. NetBSD, OpenBSD, FreeBSD ------------------------ Network renders supporting BSD releases, which typically write configuration to :file:`/etc/rc.conf`. Unique to BSD renderers is that each renderer also calls something akin to `FreeBSD.start_services`_ which will invoke applicable network services to setup the network, making network activators unneeded for BSD flavors at the moment. Network output policy ===================== The default policy for selecting a network ``renderer`` (in order of preference) is as follows: - ENI - Sysconfig - Netplan - NetworkManager - FreeBSD - NetBSD - OpenBSD - Networkd The default policy for selecting a network ``activator`` (in order of preference) is as follows: - **ENI**: using ``ifup``, ``ifdown`` to manage device setup/teardown - **Netplan**: using ``netplan apply`` to manage device setup/teardown - **NetworkManager**: using ``nmcli`` to manage device setup/teardown - **Networkd**: using ``ip`` to manage device setup/teardown When applying the policy, ``cloud-init`` checks if the current instance has the correct binaries and paths to support the renderer. The first renderer that can be used is selected. Users may override the network renderer policy by supplying an updated configuration in cloud-config. :: system_info: network: renderers: ['netplan', 'network-manager', 'eni', 'sysconfig', 'freebsd', 'netbsd', 'openbsd'] activators: ['eni', 'netplan', 'network-manager', 'networkd'] Network configuration tools =========================== ``Cloud-init`` contains a command used to test input/output conversion between formats. The :file:`tools/net-convert.py` in the ``cloud-init`` source repository is helpful in examining expected output for a given input format. If running these commands from the cloud-init source directory, make sure to set the correct path ``PYTHON_PATH=.`` CLI Interface: .. code-block:: shell-session $ cloud-init devel net-convert --help Example output: .. code-block:: usage: /usr/bin/cloud-init devel net-convert [-h] -p PATH -k {eni,network_data.json,yaml,azure-imds,vmware-imc} -d PATH -D {alpine,arch,debian,ubuntu,freebsd,dragonfly,gentoo,cos,netbsd,openbsd,almalinux,amazon,centos,cloudlinux,eurolinux,fedora,mariner,miraclelinux,openmandriva,photon,rhel,rocky,virtuozzo,opensuse,sles,openEuler} [-m name,mac] [--debug] -O {eni,netplan,networkd,sysconfig,network-manager} options: -h, --help show this help message and exit -p PATH, --network-data PATH The network configuration to read -k {eni,network_data.json,yaml,azure-imds,vmware-imc}, --kind {eni,network_data.json,yaml,azure-imds,vmware-imc} The format of the given network config -d PATH, --directory PATH directory to place output in -D {alpine,arch,debian,ubuntu,freebsd,dragonfly,gentoo,cos,netbsd,openbsd,almalinux,amazon,centos,cloudlinux,eurolinux,fedora,mariner,miraclelinux,openmandriva,photon,rhel,rocky,virtuozzo,opensuse,sles,openEuler}, --distro {alpine,arch,debian,ubuntu,freebsd,dragonfly,gentoo,cos,netbsd,openbsd,almalinux,amazon,centos,cloudlinux,eurolinux,fedora,mariner,miraclelinux,openmandriva,photon,rhel,rocky,virtuozzo,opensuse,sles,openEuler} -m name,mac, --mac name,mac interface name to mac mapping --debug enable debug logging to stderr. -O {eni,netplan,networkd,sysconfig,network-manager}, --output-kind {eni,netplan,networkd,sysconfig,network-manager} The network config format to emit Example of converting V2 to sysconfig: .. code-block:: shell-session $ cloud-init devel net-convert --network-data v2.yaml --kind yaml \ --output-kind sysconfig -d target $ cat target/etc/sysconfig/network-scripts/ifcfg-eth* Example output: .. code-block:: # Created by cloud-init on instance boot automatically, do not edit. # BOOTPROTO=static DEVICE=eth7 IPADDR=192.168.1.5/255.255.255.0 NM_CONTROLLED=no ONBOOT=yes TYPE=Ethernet USERCTL=no # Created by cloud-init on instance boot automatically, do not edit. # BOOTPROTO=dhcp DEVICE=eth9 NM_CONTROLLED=no ONBOOT=yes TYPE=Ethernet USERCTL=no .. _Cloud-init: https://launchpad.net/cloud-init .. _LXD: https://linuxcontainers.org/lxd/docs/master/cloud-init/#custom-network-configuration .. _NetworkManager: https://networkmanager.dev .. _Netplan: https://netplan.io/ .. _DigitalOcean JSON metadata: https://developers.digitalocean.com/documentation/metadata/ .. _OpenStack Metadata Service Network: https://specs.openstack.org/openstack/nova-specs/specs/liberty/implemented/metadata-service-network-info.html .. _SmartOS JSON Metadata: https://eng.joyent.com/mdata/datadict.html .. _UpCloud JSON metadata: https://developers.upcloud.com/1.3/8-servers/#metadata-service .. _Vultr JSON metadata: https://www.vultr.com/metadata/ .. _cloudinit.net.activators.select_activator: https://github.com/canonical/cloud-init/blob/main/cloudinit/net/activators.py#L249 .. _FreeBSD.start_services: https://github.com/canonical/cloud-init/blob/main/cloudinit/net/freebsd.py#L46