Overview

This interface layer handles the communication with SDN providers like flannel via the sdn-plugin interface.

Usage

Requires

This interface layer will set the following states, as appropriate:

• {relation_name}.connected The relation is established, but the sdn may not yet have provided any connection or service information.

• {relation_name}.available the SDN provider has provided its configuration information. The provided information can be accessed via the following methods:

  • sdn-plugin.get_configuration()

For example, a common application for this is configuring an applications SDN configuration, like Kubernetes.

@when('sdn-plugin.available', 'docker.available')
def container_sdn_setup(sdn):
    sdn_config = sdn.get_configuration()

    with open('/etc/default/docker', 'w') as stream:
      stream.write('DOCKER_OPTS=bip={0},mtu={1]}'.format(sdn_config['subnet'], sdn_config['mtu']))

Provides

A charm providing this interface is plugging into its related principal charm.

This interface layer will set the following states, as appropriate:

• {relation_name}.connected One or more clients of any type have been related. The charm should call the following methods to provide the appropriate information to the clients:

  • {relation_name}.set_configuration(mtu=mtu, subnet=subnet, cidr=cidr)

Example:

Note, this example will use the Flannel subnet.env file, which has a format like follows:

FLANNEL_NETWORK=10.1.0.0/16
FLANNEL_SUBNET=10.1.8.1/24
FLANNEL_MTU=1410
FLANNEL_IPMASQ=false

And the consuming python code:

@when('flannel.sdn.configured', 'sdn-plugin.connected')
def relay_sdn_configuration(host):

  config = hookenv.config()

  with open('/var/run/flannel/subnet.env') as f:
      flannel_config = f.readlines()

  for f in flannel_config:
      if "FLANNEL_SUBNET" in f:
          value = f.split('=')[-1].strip()
          subnet = value
      if "FLANNEL_MTU" in f:
          value = f.split('=')[1].strip()
          mtu = value

    host.send_sdn_info(mtu, subnet, hookenv.config('cidr'))

Contact Information

Maintainer

• Charles Butler charles.butler@canonical.com

Etcd

• Flannel home page
• Flannel bug trackers
• Flannel Juju Charm