➜  ~ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                    NAMES
14310d9f0ece        postgres:9.4        "docker-entrypoint.s…"   5 minutes ago       Up 5 minutes        0.0.0.0:5432->5432/tcp   postgres

➜  postgres psql --version
psql (PostgreSQL) 9.4.22
➜  postgres psql -h 127.0.0.1 -p 5432
// hangs

➜  postgres nc -vz localhost 5432
found 0 associations
found 1 connections:
     1: flags=82<CONNECTED,PREFERRED>
    outif lo0
    src ::1 port 51856
    dst ::1 port 5432
    rank info not available
    TCP aux info available

Connection to localhost port 5432 [tcp/postgresql] succeeded!

➜  postgres lsof -n -i :5432 | grep LISTEN
com.docke 13037 steve   27u  IPv4 0xd8d4bc5463376f87      0t0  TCP *:postgresql (LISTEN)
com.docke 13037 steve  115u  IPv6 0xd8d4bc5462ccdd07      0t0  TCP [::1]:postgresql (LISTEN)