host.docker.internal exists only in Windows WSL because Docker Desktop for Windows runs Docker daemon inside the special WSL VM Docker-Desktop. It has its own localhost and its own WSL2 interface to communicate with Windows. This VM has no static IP. The IP is generated every time when VM is created and passed via host.docker.internal in the generated /etc/hosts to every distro. Although there is no bridge or real v-switch all ports opened on eth0 of VM internal network are mapped on the host Local network, BUT NOT ON THE ETH0 OF THE HOST. There is no real bridge and port mapping - nothing to configure. Inside WSL VM its Localhost is the same as the localhost of the Linux machine. 2 processes inside WSL VM can communicate via localhost. Cross-distro IPC must use host.docker.internal. It is possible to create bridge inside WSL VM -Docker does it.

对于linux，我可以使用我试图连接到的服务名，例如，我的一个容器(php-fpm)试图连接到mysql，所以我使用mysql作为主机名，因为这是我的docker-compose中的服务名

对于linux系统，从docker引擎的主版本20.04开始，您现在也可以通过host.docker.internal与主机通信。这不会自动工作，但你需要提供以下运行标志:

--add-host=host.docker.internal:host-gateway

请点击这里查看答案:https://stackoverflow.com/a/61424570/3757139

请参见下面的答案，添加到docker-compose文件- https://stackoverflow.com/a/67158212/243392

如果你正在使用Docker Compose + Linux，你必须手动添加它(至少现在)。在docker-compose上使用extra_hosts。yaml文件:

version: '3.7'

services:

  fpm:
    build:
      context: .
    extra_hosts:
      - "host.docker.internal:host-gateway"

不要忘记更新Docker，因为这只适用于Docker v20.10+。

来源:https://github.com/docker/for-linux/issues/264#issuecomment-784985736

https://github.com/docker/for-linux/issues/264

IP=$(ip -4 route list match 0/0 | awk '{print $3}')
echo "Host ip is $IP"
echo "$IP   host.docker.internal" | sudo tee -a /etc/hosts

它会将host.docker.internal添加到您的主机。然后可以在xdebug配置中使用它。

下面是docker-compose.yml中env变量的例子

XDEBUG_CONFIG: remote_host=host.docker.internal remote_autostart=On remote_enable=On idekey=XDEBUG remote_log=/tmp/xdebug.log remote_port=9999

使用docker0接口ip(比如172.17.0.1)可能是一个很好的解决方案。

只要确保您需要访问的服务侦听外部连接即可。一个典型的例子是Mysql，默认绑定到127.0.0.1，导致无法访问，直到你允许外部连接。绑定到0.0.0.0)