Each instance is assigned a fixed IP address when it is created.
These private addresses are used for communication between instances within the same project.
But instances need an ip address to communicate with outside of the project.
For this, floating IPs are allocated to the project. Its can be associated or dissociated from an instance at any time.
The quota given for a project determines the maximum number of floating ip addresses that can be allocated to the project.
Run the following command line to get the list of available floating ip addresses.
$ openstack floating ip list
To allocate a floating ip to the project, you must create an address in the public subnet.
You can use the following method :
$ openstack floating ip create \ --dns-name <nomDNS> --dns-domain nova.u-ga.fr. \ public
This documentation will later explain how and why to associate or disassociate a floating IP from an instance.