4.18 Murano Cannot Access External Network

The Murano engine cannot access the external network when deploying an application. When you deploy a Murano application, an error similar to the following is in the murano_engine logs:

murano_engine: ... getDefaultRouter'no external network found' % router_name

Workaround: Perform one of the following:

Create an external network named ext-net and the murano-default-router is automatically created and connected to the network, for example:
```
$ neutron net-create ext-net --router:external
```

Create a router named murano-default-router and attach it to the external network.

$ neutron router-create murano-default-router
$ neutron router-gateway-set murano-default-router ext-net

Bug: 21976631