I have a problem with pgpool package that I installed on a nixos.

context : 3 VMs , each of them can be reachable on the port 5432

nc -v clustering-0 5432
succeeded
nc -v clustering-1 5432
succeeded
nc -v clustering-2 5432
succeeded

On each, I installed pgpool package

environment.systemPackages = [
        pkgs.pgpool
        ];

I’ve configured it :

wd_lifecheck_method = 'heartbeat'
wd_interval = 10
wd_heartbeat_keepalive = 2
wd_heartbeat_deadtime = 30

heartbeat_hostname0 = 'clustering-0'
heartbeat_port0 = 9694
heartbeat_device0 = ''

heartbeat_hostname1 = 'clustering-1'
heartbeat_port1 = 9694
heartbeat_device1 = ''

heartbeat_hostname2 = 'clustering-2'
heartbeat_port2 = 9694
heartbeat_device2 = ''

However when I turn on gppool, I have this result in my logs on the VM clustering-0 :

2024-05-19 19:55:26.209: heart_beat_sender pid 1596: ERROR:  failed to send watchdog heartbeat, gethostbyname() failed
2024-05-19 19:55:26.209: heart_beat_sender pid 1596: DETAIL:  gethostbyname on "clustering-1" failed with reason: "No address associated with name"
2024-05-19 19:55:26.284: health_check2 pid 1828: LOG:  health check retrying on DB node: 2 (round:2)
2024-05-19 19:55:26.518: heart_beat_sender pid 1600: ERROR:  failed to send watchdog heartbeat, gethostbyname() failed
2024-05-19 19:55:26.518: heart_beat_sender pid 1600: DETAIL:  gethostbyname on "clustering-2" failed with reason: "No address associated with name"
2024-05-19 19:55:27.287: health_check2 pid 1828: LOG:  health check retrying on DB node: 2 (round:3)
2024-05-19 19:55:27.694: health_check1 pid 1827: LOG:  health check retrying on DB node: 1 (round:1)
2024-05-19 19:55:28.212: heart_beat_sender pid 1596: ERROR:  failed to send watchdog heartbeat, gethostbyname() failed
2024-05-19 19:55:28.212: heart_beat_sender pid 1596: DETAIL:  gethostbyname on "clustering-1" failed with reason: "No address associated with name"
2024-05-19 19:55:28.291: health_check2 pid 1828: LOG:  health check failed on node 2 (timeout:0)
2024-05-19 19:55:28.291: health_check2 pid 1828: LOG:  health check failed on quarantine node 2 (timeout:0)
2024-05-19 19:55:28.291: health_check2 pid 1828: DETAIL:  ignoring..

Is there a DNS configuration involved by the usage of pgpool ?