Eu resolvi o problema, estou usando o centos7 e tive que:
1.) adicione isto em /etc/my.cnf.d/server.cnf
[mysqld]
bind-address=0.0.0.0
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
binlog_format=ROW
wsrep_cluster_address='gcomm://'
wsrep_cluster_name='galera_cluster'
wsrep_node_name='node1'
2.) Eu tive que desabilitar o selinux e o firewalld para permitir que os outros nós se conectassem ao cluster. (Eu sei que para produção usa você deve lidar com as regras de selinux e firewall, mas no meu caso foi um teste em uma máquina local, então se você usá-lo para prod manipular isso corretamente)
3.) nos nós de conexão, especifique o /etc/my.cnf.d/server.cnf com:
[mysqld]
bind-address=0.0.0.0
[galera]
wsrep_on=ON
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
binlog_format=ROW
wsrep_cluster_address='gcomm://ip_of_the_master,ip_of_other_nodes'
wsrep_cluster_name='galera_cluster'
wsrep_node_name='nodeX'
Em seguida, inicie o serviço mysql.
Agora meu cluster se parece com isso:
MariaDB [(none)]> SHOW GLOBAL STATUS LIKE 'wsrep_%';
+------------------------------+-------------------------------------------------------------+
| Variable_name | Value |
+------------------------------+-------------------------------------------------------------+
| wsrep_apply_oooe | 0.000000 |
| wsrep_apply_oool | 0.000000 |
| wsrep_apply_window | 1.000000 |
| wsrep_causal_reads | 0 |
| wsrep_cert_deps_distance | 60.887500 |
| wsrep_cert_index_size | 24 |
| wsrep_cert_interval | 0.000000 |
| wsrep_cluster_conf_id | 73 |
| wsrep_cluster_size | 3 |
| wsrep_cluster_state_uuid | c44d1346-a5c3-11e5-9a68-ca1db8f95be1 |
| wsrep_cluster_status | Primary |
| wsrep_commit_oooe | 0.000000 |
| wsrep_commit_oool | 0.000000 |
| wsrep_commit_window | 1.000000 |
| wsrep_connected | ON |
| wsrep_evs_delayed | |
| wsrep_evs_evict_list | |
| wsrep_evs_repl_latency | 0/0/0/0/0 |
| wsrep_evs_state | OPERATIONAL |
| wsrep_flow_control_paused | 0.000000 |
| wsrep_flow_control_paused_ns | 0 |
| wsrep_flow_control_recv | 0 |
| wsrep_flow_control_sent | 0 |
| wsrep_gcomm_uuid | 3c438933-a727-11e5-b2f2-f659b1338a74 |
| wsrep_incoming_addresses | 100.120.88.245:3306,100.120.88.244:3306,100.120.88.246:3306 |
| wsrep_last_committed | 400 |
| wsrep_local_bf_aborts | 0 |
| wsrep_local_cached_downto | 1 |
| wsrep_local_cert_failures | 0 |
| wsrep_local_commits | 391 |
| wsrep_local_index | 0 |
| wsrep_local_recv_queue | 0 |
| wsrep_local_recv_queue_avg | 0.071429 |
| wsrep_local_recv_queue_max | 2 |
| wsrep_local_recv_queue_min | 0 |
| wsrep_local_replays | 0 |
| wsrep_local_send_queue | 0 |
| wsrep_local_send_queue_avg | 0.000000 |
| wsrep_local_send_queue_max | 1 |
| wsrep_local_send_queue_min | 0 |
| wsrep_local_state | 4 |
| wsrep_local_state_comment | Synced |
| wsrep_local_state_uuid | c44d1346-a5c3-11e5-9a68-ca1db8f95be1 |
| wsrep_protocol_version | 7 |
| wsrep_provider_name | Galera |
| wsrep_provider_vendor | Codership Oy <[email protected]> |
| wsrep_provider_version | 25.3.9(r3387) |
| wsrep_ready | ON |
| wsrep_received | 182 |
| wsrep_received_bytes | 17414 |
| wsrep_repl_data_bytes | 52304 |
| wsrep_repl_keys | 1183 |
| wsrep_repl_keys_bytes | 18664 |
| wsrep_repl_other_bytes | 0 |
| wsrep_replicated | 400 |
| wsrep_replicated_bytes | 96568 |
| wsrep_thread_count | 2 |
+------------------------------+-------------------------------------------------------------+