参考
https://www.cnblogs.com/jsonhc/p/7823286.html
执行
docker network ls
NETWORK ID NAME DRIVER SCOPE
3128bb034163 bridge bridge local
0acd8b6f9ff5 host host local
d8f63fd8ab0a none null local
9222aa01dbf5 ***s-api_***apin bridge local
93992c4bdd0d travellist-demo_travellist bridge local可以看出在启动服务的时候创建了服务级别的网络***s-api_***apin
t****@laravel-docker-t****:~/***api/***s-api$ docker exec -it ***api-nginx ping ***api-app
PING ***api-app (172.21.0.4): 56 data bytes
64 bytes from 172.21.0.4: seq=0 ttl=64 time=0.142 ms
64 bytes from 172.21.0.4: seq=1 ttl=64 time=0.128 ms
64 bytes from 172.21.0.4: seq=2 ttl=64 time=0.158 ms
64 bytes from 172.21.0.4: seq=3 ttl=64 time=0.105 ms
64 bytes from 172.21.0.4: seq=4 ttl=64 time=0.152 ms
64 bytes from 172.21.0.4: seq=5 ttl=64 time=0.137 ms
64 bytes from 172.21.0.4: seq=6 ttl=64 time=0.164 ms
64 bytes from 172.21.0.4: seq=7 ttl=64 time=0.133 ms
64 bytes from 172.21.0.4: seq=8 ttl=64 time=0.128 ms
64 bytes from 172.21.0.4: seq=9 ttl=64 time=0.163 ms
64 bytes from 172.21.0.4: seq=10 ttl=64 time=0.148 ms
64 bytes from 172.21.0.4: seq=11 ttl=64 time=0.148 ms
64 bytes from 172.21.0.4: seq=12 ttl=64 time=0.185 ms
^C
--- ***api-app ping statistics ---
13 packets transmitted, 13 packets received, 0% packet loss
round-trip min/avg/max = 0.105/0.145/0.185 ms
t****@laravel-docker-t****:~/***api/***s-api$服务nginx【***api-nginx】和php【***api-app】在网络***s-api_***apin实现了互联通信
在nginx【***api-nginx】服务中能够访问php【***api-app】的服务，
在compose编排中级别的访问是对service级别的访问，所以在nginx服务配置文件中对应的php能够实现，不会导致nginx启动失败
--links也是能够使得服务间进行访问的，但是官方现在不推荐—links links和depends_on搭配使用，确定先后启动顺序及相互间通讯。还有expose。external_links