VNF Primitive Config

The purpose of the Config primitive is to change the configuration your VNF application.

Config			Required
Day 0	Day 1	Day 2
No	Yes	Yes	No

The Config Primitive is handled differently than Service Primitives.

The configuration parameters you'd like to make available for modification are defined in the VNF Charm's config.yaml:

options:
  target_latency:
    default: 100000
    description: Target request latency for overload control (microseconds)
    type: int

The configuration is then exposed to the operator via the VNF Descriptor:

Example code:

@when('config.changed')
def apply_vnf_config():
    """Runs when the config-changed hook is executed."""
    err = ''
    try:
        cfg = config()
        """
        Run the command(s) necessary to perform a safe stop of your VNF
        This could be a single command that encapsulates your stop process...

        """
        result, err = charms.sshproxy._run("/srv/myvnf/config.sh target_latency={}".format(cfg['target_latency']))
    except:
        action_fail('Restart failed:' + err)
    else:
        action_set({'outout': result})

    # Restart your VNF for the change to take affect, if necessary.
    restart_vnf()

For a full example of creating a VNF charm, please see Creating your own VNF charm (Release FOUR).