Docker + Xdebug + VSCode Could not connect to client

You can have your docker container connect to your host by configuring PHP appropriately.

Note that I've used Docker's host.docker.internal domain, that always points to the host IP.

xdebug.remote_enable=1xdebug.remote_port=9000xdebug.idekey=dockerxdebug.profiler_enable=0xdebug.profiler_enable_trigger=1xdebug.remote_host=host.docker.internal

There's no need to open ports to the docker container. Just make sure that your debugging application can listen on the appointed port (9000 in my case) and that this port is not occupied.

Take for example this PhpStorm configuration:

Troubleshooting

Validate that xdebug is installed, run in the php container:

php -i | grep xdebug

Make sure that you're editing the appropriate .ini files, check:

php -i | grep \.ini

If you have idekey enabled, make sure to configure them in your IDE too:

There's a Debugger Config Validator in PhpStorm if you're exposing PHP scripts on a webserver:

Try to open port 9001 in the docker-compose.yml by inserting:

ports: - "9001:9001"

Example

services:  webserver:    build:       context: ./bin/webserver    container_name: '7.1.x-webserver'    restart: 'always'    ports:      - "80:80"      - "443:443"      - "9001:9001"    links:       - mysql    volumes:       - ${DOCUMENT_ROOT-./www}:/var/www/html      - ${PHP_INI-./config/php/php.ini}:/usr/local/etc/php/php.ini      - ${VHOSTS_DIR-./config/vhosts}:/etc/apache2/sites-enabled      - ${LOG_DIR-./logs/apache2}:/var/log/apache2

See more about configuring docker-compose.yml: https://docs.docker.com/compose/compose-file/

You might be able to use expose. We have that in some of our old Dockerfiles which is intended to allow xDebug connections, but I haven't used it personally.

    expose:      - "9001"

1. You should open port 9001 in your host machine, not in Docker.
2. Also try to check if Xdebug is configured properly: add phpinfo() to your code and open that page in browser. You shold see xdebug enabled
3. If Xdebug enabled, maybe your IDE settings are incorrect