LGTM, the cluster was formed successfully with this change /etc/hosts contained IPv4 values.
$ juju run --service rabbitmq-server 'grep machine /etc/hosts'
- MachineId: "1"
Stderr: "Warning: Permanently added '10.0.3.7' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.176 freyes-local-machine-3
10.0.3.241 freyes-local-machine-2
'
UnitId: rabbitmq-server/0
- MachineId: "2"
Stderr: "Warning: Permanently added '10.0.3.241' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.176 freyes-local-machine-3
10.0.3.7 freyes-local-machine-1
'
UnitId: rabbitmq-server/1
- MachineId: "3"
Stderr: "Warning: Permanently added '10.0.3.176' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.7 freyes-local-machine-1
LGTM, the cluster was formed successfully with this change /etc/hosts contained IPv4 values.
$ juju run --service rabbitmq-server 'grep machine /etc/hosts' local-machine- 3
- MachineId: "1"
Stderr: "Warning: Permanently added '10.0.3.7' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.176 freyes-
10.0.3.241 freyes- local-machine- 2
' local-machine- 3
UnitId: rabbitmq-server/0
- MachineId: "2"
Stderr: "Warning: Permanently added '10.0.3.241' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.176 freyes-
10.0.3.7 freyes- local-machine- 1
' local-machine- 1
UnitId: rabbitmq-server/1
- MachineId: "3"
Stderr: "Warning: Permanently added '10.0.3.176' (ECDSA) to the list of known hosts.\r\n"
Stdout: '10.0.3.7 freyes-
10.0.3.241 freyes- local-machine- 2
'
UnitId: rabbitmq-server/2