我的最终目标是允许运行FastAPI应用程序的容器与主机上的MySQL数据库通信。
首先我尝试使用host.docker.internal

停靠文件

FROM debian:latest

RUN apt update && apt install -y \
    netcat \
    iputils-ping

CMD echo "tailing /dev/null" && tail -f /dev/null

停靠-撰写.yml

version: "3.2"

services:
  test:
    build:
      context: "."
    extra_hosts:
      - "host.docker.internal:host-gateway"

预期行为：ping工程，nc -vz工程

特别是，使用nc-vz时，我希望看到类似以下的内容：

root@9fe8de220d44:/# nc -vz host.docker.internal 80
Connection to host.docker.internal (172.17.0.1) port 80 (tcp) succeeded!

实际行为：ping可以工作，nc -vz不能

root@5981bcfbf598:/# ping host.docker.internal
PING host.docker.internal (172.17.0.1) 56(84) bytes of data.
64 bytes from host.docker.internal (172.17.0.1): icmp_seq=1 ttl=64 time=0.079 ms
64 bytes from host.docker.internal (172.17.0.1): icmp_seq=2 ttl=64 time=0.067 ms
64 bytes from host.docker.internal (172.17.0.1): icmp_seq=3 ttl=64 time=0.068 ms
^C
--- host.docker.internal ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2013ms
rtt min/avg/max/mdev = 0.067/0.071/0.079/0.005 ms
root@5981bcfbf598:/# nc -vz host.docker.internal 80
nc: connect to host.docker.internal (172.17.0.1) port 80 (tcp) failed: Connection refused

在主机上

我在端口80上运行Apache

$ netstat -tulpn
...
tcp6       0      0 :::80                   :::*                    LISTEN      1258/apache2

此外，我的防火墙配置为允许所有入站请求到达端口80：firewall says http port 80 allows all ipv4 and ipv6
操作系统和Docker版本：

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.6 LTS
Release:    18.04
Codename:   bionic
$ docker --version
Docker version 20.10.21, build baeda1f

手动指定网络也失败

在host.docker.internal失败后，我按照下面的说明使用手动指定的网络从容器连接到Linux主机（在我的例子中是Ubuntu 18.04）：https://stackoverflow.com/a/70725882
以下是我的设置：

停靠文件

FROM debian:latest

RUN apt update && apt install -y \
    netcat \
    iputils-ping

CMD echo "tailing /dev/null" && tail -f /dev/null

停靠-撰写.yml

version: "3.2"

networks:
  test:
    name: test-network
    attachable: true
    ipam:
      driver: default
      config:
        - subnet: 172.42.0.0/16
          ip_range: 172.42.5.0/24
          gateway: 172.42.0.1

services:
  test:
    build:
      context: "."
    networks:
      - test

确认网关

$ docker inspect test-test-1  -f '{{range .NetworkSettings.Networks}}{{.Gateway}}{{end}}'
172.42.0.1

ping有效

root@07f81c211a0c:/# ping 172.42.0.1
PING 172.42.0.1 (172.42.0.1) 56(84) bytes of data.
64 bytes from 172.42.0.1: icmp_seq=1 ttl=64 time=0.056 ms
64 bytes from 172.42.0.1: icmp_seq=2 ttl=64 time=0.068 ms
64 bytes from 172.42.0.1: icmp_seq=3 ttl=64 time=0.065 ms

预期行为：nc -vz成功

根据https://stackoverflow.com/a/70725882处的说明：

root@9fe8de220d44:/# nc -vz 172.18.0.1 80
Connection to 172.18.0.1 80 port [tcp/http] succeeded!

实际行为：nc-vz失败

root@07f81c211a0c:/# nc -vz 172.42.0.1 80
nc: connect to 172.42.0.1 port 80 (tcp) failed: Connection refused

我做错了什么？

提前感谢您的帮助！