Overview

This principle charm provides the OpenStack Neutron API service which was previously provided by the nova-cloud-controller charm.

When this charm is related to the nova-cloud-controller charm the nova-cloud controller charm will shutdown its api service, de-register it from keystone and inform the compute nodes of the new neutron url.

Usage

To deploy (partial deployment only):

juju deploy neutron-api
juju deploy neutron-openvswitch

juju add-relation neutron-api mysql
juju add-relation neutron-api rabbitmq-server
juju add-relation neutron-api neutron-openvswitch
juju add-relation neutron-api nova-cloud-controller

This charm also supports scale out and high availability using the hacluster charm:

juju deploy hacluster neutron-hacluster
juju add-unit neutron-api
juju set neutron-api vip=<VIP FOR ACCESS>
juju add-relation neutron-hacluster neutron-api

HA/Clustering

There are two mutually exclusive high availability options: using virtual IP(s) or DNS. In both cases, a relationship to hacluster is required which provides the corosync back end HA functionality.

To use virtual IP(s) the clustered nodes must be on the same subnet such that the VIP is a valid IP on the subnet for one of the node's interfaces and each node has an interface in said subnet. The VIP becomes a highly-available API endpoint.

At a minimum, the config option 'vip' must be set in order to use virtual IP HA. If multiple networks are being used, a VIP should be provided for each network, separated by spaces. Optionally, vip_iface or vip_cidr may be specified.

To use DNS high availability there are several prerequisites. However, DNS HA does not require the clustered nodes to be on the same subnet. Currently the DNS HA feature is only available for MAAS 2.0 or greater environments. MAAS 2.0 requires Juju 2.0 or greater. The clustered nodes must have static or "reserved" IP addresses registered in MAAS. The DNS hostname(s) must be pre-registered in MAAS before use with DNS HA.

At a minimum, the config option 'dns-ha' must be set to true and at least one of 'os-public-hostname', 'os-internal-hostname' or 'os-internal-hostname' must be set in order to use DNS HA. One or more of the above hostnames may be set.

The charm will throw an exception in the following circumstances: If neither 'vip' nor 'dns-ha' is set and the charm is related to hacluster If both 'vip' and 'dns-ha' are set as they are mutually exclusive. If 'dns-ha' is set and none of the os-{admin,internal,public}-hostname(s) are set

Restrictions

This charm only support deployment with OpenStack Icehouse or better.

Internal DNS for Cloud Guests

The charm supports enabling internal DNS resolution for cloud guests in accordance with the OpenStack DNS integration guide. To enable internal DNS resolution, the 'enable-ml2-dns' option must be set to True. When enabled, the domain name specified in the 'dns-domain' will be advertised as the nameserver search path by the dhcp agents.

The Nova compute service will leverage this functionality when enabled. When ports are allocated by the compute service, the dns_name of the port is populated with a DNS sanitized version of the instance's display name. The Neutron DHCP agents will then create host entries in the dnsmasq's configuration files matching the dns_name of the port to the IP address associated with the port.

Note that the DNS nameserver provided to the instance by the DHCP agent depends on the tenant's network setup. The Neutron DHCP agent only advertises itself as a nameserver when the Neutron subnet does not have nameservers configured. If additional nameservers are needed and internal DNS is desired, then the IP address of the DHCP port should be added to the subnet's list of configured nameservers.

For more information refer to the OpenStack documentation on DNS Integration.

Network Space support

This charm supports the use of Juju Network Spaces, allowing the charm to be bound to network space configurations managed directly by Juju. This is only supported with Juju 2.0 and above.

API endpoints can be bound to distinct network spaces supporting the network separation of public, internal and admin endpoints.

Access to the underlying MySQL instance can also be bound to a specific space using the shared-db relation.

To use this feature, use the --bind option when deploying the charm:

juju deploy neutron-api --bind "public=public-space internal=internal-space admin=admin-space shared-db=internal-space"

alternatively these can also be provided as part of a juju native bundle configuration:

neutron-api:
  charm: cs:xenial/neutron-api
  num_units: 1
  bindings:
    public: public-space
    admin: admin-space
    internal: internal-space
    shared-db: internal-space

NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.

NOTE: Existing deployments using os-*-network configuration options will continue to function; these options are preferred over any network space binding provided if set.

Additional Middleware Requests by Neutron Plugin Charms

Some neutron plugins may require additional middleware to be added to api-paste.ini. In order to support that a subordinate may pass extra_middleware via the neutron-plugin-api-subordinate relation.

Relation data to be set by subordinates: {'extra_middleware': [{ 'type': 'middleware_type', 'name': 'middleware_name', 'config': { 'setting_1': 'value_1', 'setting_2': 'value_2'}}]}

It would not be correct to do that from your own plugin as this requires the neutron-api service restart which should be handled in this charm.

The developer guide for Neutron contains a description of the startup process which makes it clear that api-paste.ini is parsed only once in neutron-api's lifetime (see the "WSGI Application" section):

https://git.openstack.org/cgit/openstack/neutron/tree/doc/source/devref/api_layer.rst#n49

For the api-paste.ini format in general, please consult PasteDeploy repository docs/index.txt, "Config Format" section: https://bitbucket.org/ianb/pastedeploy

Classes in loadwsgi.py contain config_prefixes that can be used for middleware types - these are the prefixes the charm code validates passed data against:

4b27133a2a/paste/deploy/loadwsgi.py