Xdebug 3 doesn't connect in docker - docker

Question

I used this docker-compose file with the Xdebug options that worked for me in a local Xdebug installation, but doesn't work in Docker.
version: '3'
services:
app:
container_name: php7.3-xdebug
image: 'php7.3-xdebug-i'
ports:
- '9090:80'
build:
context: ./
dockerfile: ./dockerfile
volumes:
- ./:/var/www/html
environment:
XDEBUG_CONFIG: zend_extension=xdebug.so xdebug.mode=debug xdebug.start_with_request=yes xdebug.client_host=host.docker.internal
This is the Dockerfile:
FROM php:7.3.28-apache-buster
RUN pecl install xdebug-3.0.4 \
&& docker-php-ext-enable xdebug
COPY . /var/www/html
WORKDIR /usr/src/myapp
and this launch.json in VSCode:
{
"version": "0.2.0",
"configurations": [
{
"name": "Listen for XDebug",
"type": "php",
"request": "launch",
"port": 9003,
"pathMappings": {
"/var/www/html": "${workspaceFolder}",
},
},
{
"name": "Launch currently open script",
"type": "php",
"request": "launch",
"program": "${file}",
"cwd": "${fileDirname}",
"port": 9003
}
]
}
I tried a lot of configs but there is no way to make it work.

Answer 1

XDEBUG_CONFIG: zend_extension=xdebug.so xdebug.mode=debug
xdebug.start_with_request=yes xdebug.client_host=host.docker.internal
This line is incorrect:
You can't load extensions through an Xdebug specific environment variable (but the docker-php-ext-enable xdebug line in your Dockerfile should have taken care of this already).
If you want to set settings through XDEBUG_CONFIG, then you should not prefix them with xdebug., which is explained in the documentation.
The documentation also says that only a select set of settings can be set through XDEBUG_CONFIG, and start_with_request is not one of these. It needs to be set in a PHP ini file.
To set Xdebug's mode, you need to use the XDEBUG_MODE environment variable instead, as is explained in the documentation again.