If "hostname": "0.0.0.0" is not set in the VSCode launch configuration, breakpoints are not hit.

1. Build with docker build -t php-xdebug-docker .
2. Run in interactive mode with docker run -it -p 9003:9003 php-xdebug-docker /bin/bash
3. Run XDebug launch script in VSCode that looks like this:

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Listen for Xdebug",
      "type": "php",
      "request": "launch",
      "port": 9003,
      "pathMappings": {
        "/tmp": "${workspaceFolder}"
      },
      "log": true
    }
  ]
}

4. Set a breakpoint in index.php
5. From the bash terminal in the container, execute the PHP script with php /tmp/index.php
6. See that breakpoints set in index.php are not hit