Floating IP Association vs Floating IP

asked 2017-03-15 13:29:10 -0500

marco1982 gravatar image

Hi all,

I'm relatively new to Openstack and I would like to have some clarifications about OS::Neutron::FloatingIP and OS::Neutron::FloatingIPAssociation.

My goal is to instantiate VMs via heat template and assign them a floating IP address. My heat templates creates a private management network (where the VMs are attached to) and a router that connects that private network to the external network.

I'm using Openstack Mitaka.

When it comes to assigning a floating IP to VMs, by looking at the documentation available on the web, the way to do it should be:

resources:
  port:
    type: OS::Neutron::Port
    properties:
      network: { get_resource: private_network }

  floating_ip:
    type: OS::Neutron::FloatingIP
    properties:
      floating_network: { get_param: public_network }

  floating_ip_assoc:
    type: OS::Neutron::FloatingIPAssociation
    properties:
      floatingip_id: { get_resource: floating_ip }
      port_id: { get_resource: port }

However, in my heat template, I do something like this:

resources:
  port:
    type: OS::Neutron::Port
    properties:
      network: { get_resource: private_network }

  floating_ip:
    type: OS::Neutron::FloatingIP
    properties:
      floating_network: { get_param: public_network }
      port_id: { get_resource: port }

In this example, I avoid using OS::Neutron::FloatingIPAssociation and I specify port_id directly in the OS::Neutron::FloatingIP resource.

This works well. So, my question is: what is the difference between the two (apparently both working) approaches? When is it better to use one over the other?

Thanks

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Comments

If the port has one Fixed IP, your template's approach is ok. If the port has more than one Fixed IP, one of them has to be chosen for Floating IP's forwarded traffic. Selecting a Fixed IP is a feature of "OS::Neutron::FloatingIPAssociation"'s "fixed_ip_address" property.

Senol Erdogan gravatar imageSenol Erdogan ( 2017-08-26 01:12:20 -0500 )edit