We are currently using Openstack newtown. We can access the API using client on public endpoint from any computer, but the vm don't have access to it, they can ping the IP and dns name but can't curl or access using openstack-client. How can we allow connection from VM to API ?
Assuming your public API endpoint is externally accessible, the network on which your virtual machine resides will need external access. This can be achieved in a few different ways, depending on your current configuration. You can create a Neutron provider network/subnet which will provide access to a physical network and gateway to the outside world. You can then boot your instance directly on the provider network. More information on Neutron provider networks can be found at docs.openstack.org.