Debugging Web Applications In PHPStorm With Xdebug And Docker

Overview

How to debug a PHP web application in PHPStorm using Docker and XDebug.

PHP configuration

Make sure that a PHP interpreter is selected, and that the PHP installation has XDebug included.

In PHPStorm: Preferences > Language & Frameworks > PHP > CLI interpreter

From the command line: php -v. Make sure that the xdebug extension is displayed.

Docker server

The Docker server is a virtual Linux server that runs the web server which is used to host the web application to be debugged. It is important to keep in mind that the software and filesystem of this server is independent of the local filesystem where the app is being developed.

When this virtual server is spun up, it must be configured such that it can host the web application in a state where it can be run and debugged.

Preferences > Language & Frameworks > PHP > Servers

Click the "plus" icon to create a new server.

• Name: docker-server
• Host: localhost
• Port: 80
• Debugger: Xdebug
• Use path mappings: checked

Then under path mappings create associations between project files and their respective locations in the Docker container, e.g.:

The host and port reference host and port within the Docker container. This applies to the path mappings as well.

The container's HTML root is /var/www/html. This path may or may not exist on the local file system, but that doesn't impact anything here.

Two project file directories cannot point to the same path on the server (e.g. bfhhand_web and common_lib can't coexist in the same root directory as they do on production.)

Run configuration

Run > Edit Configurations...

Click the "plus" icon to create a new Debug Configuration.

Select PHP Remote Debug

• Name: docker
• Server: docker-server
• IDE key: docker

docker-server is the server that was created in the previous step.

The value of the IDE Key must match the value that is put into the xdebug.ini file that is created later in the process.

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Xdebug preferences

These are the defaults, they can be confirmed, but don't need to be changed

Preferences > Languages & Frameworks > PHP > Debug > Xdebug

• Debug port: 9001
• Can accept external connections: checked

Docker container configuration

The three files used in the Docker container configuration (Dockerfile, xdebug.ini, docker-compose.yml) are all located in the PHPStorm project root directory. These files should not be uploaded to production. The actual web files should be placed one directory down from the root, e.g. in a directory named app.

Dockerfile

FROM php:5.6-apache

# install utilities such as curl, git, vim
RUN apt-get update &&\
    apt-get install --no-install-recommends --assume-yes --quiet ca-certificates curl git vim &&\
    rm -rf /var/lib/apt/lists/*

# install php extensions redis, xdebug, mysqli, etc.
RUN pecl install redis-2.2.7 \
    && pecl install xdebug-2.5.5 \
    && docker-php-ext-install mbstring pdo pdo_mysql mysqli \
    && docker-php-ext-enable redis xdebug

# create accessible apache logs
RUN mkdir /var/log/httpd/
ENV APACHE_LOG_DIR /var/log/httpd

# enable mod_rewrite
RUN a2enmod headers rewrite

# bypass CMS password in development environment
RUN mkdir /home/myacct/ && \
	mkdir /home/myacct/.htpasswds/ && \
	mkdir /home/myacct/.htpasswds/mysite/
COPY htpasswd/passwd /home/myacct/.htpasswds/mysite/

# Xdebug settings
COPY xdebug.ini /usr/local/etc/php/conf.d/

# make httpd accessible
EXPOSE "80"

The most important functions of this file are

• Pull a PHP image.
• Install Xdebug and MySql PHP extensions.
• Applies local xdebug.ini to the container.
• Makes http port 80 available in the container.

Other conveniences built into the file:

• Install curl, git, and vim in the container.
• Log server errors to accessible log file.
• Enable mod_rewrite directives and any non-default modules referenced in .htaccess.

xdebug.ini

zend.extension="/usr/local/lib/php/extensions/no-debug-non-zts-20170718/xdebug.so"
xdebug.remote_enable=1
xdebug.remote_handler="dbgp"
xdebug.remote_port=9001
xdebug.remote_autostart=1
xdebug.remote_connect_back=0
xdebug.idekey="docker"
xdebug.remote_host=docker.for.mac.localhost
xdebug.remote_log="/tmp/xdebug.log"

• xdebug.idekey refers back to the IDE key entered in PHPStorm's run configuration.
• xdebug.remote_host could be the IP address of the local machine, but this would have to be changed any time the IP address changes. See below for the work-around that explains the setting above.
  • In a Mac OS terminal find the current IP with ipconfig getifaddr en0
• xdebug.remote_connect_back must be set to "0" or else it would override the xdebug.remote_host settting.
• xdebug.remote_port must be the same as PHPStorm > Preferences > Languages & Frameworks > PHP > Debug > Xdebug > Debug Port.
• If you're debugging more than one PHP web application, then you either remove all Docker images except the one for the current app, or make sure that they are using different ports.

docker-compose.yml

version: '2'
services:
  app:
    build:
      context: .
    image: xdebug-bfhhand:latest
    volumes:
      - ./:/var/www/html
      - ~/develop/bfhhand/keys:/var/www/keys
      - ~/develop/common_lib:/var/www/html/common_lib
    ports:
      - "80:80"

• The context directive specifies where the Dockerfile is located.
• image specifies the name of the Docker container that will be created.
• volumes maps local directories to directories in the Docker container. These mappings correspond to the mappings found in PHPStorm > Preferences > Language & Frameworks > PHP > Servers > docker > path mappings.
• ports maps the port used to reach the container with the port used inside the container.

Starting the Docker container

$ docker-compose build
$ docker-compose up -d
$ curl localhost

or simply

$ docker-compose up -d --build
$ curl localhost

The -d option is for "detached" to get the terminal prompt back after running the command.

The server is tested with curl localhost.

Stop the container with

$ docker-compose down

Remove the image with

$ docker rmi [IMAGE_NAME]

Connecting the the Docker container with PHPStorm

Chrome extension

Install XDebug Helper extension in browser.

In the extension options, select PHPStorm as the predefined IDE key (PHPSTORM) or "Other" to specify a custom IDE key. This key must match the key specified in the docker run configuration (Run menu > Edit Configurations... > IDE Key (Session ID)).

Make sure that the extension is active by clicking on the extension icon in the browser toolbar, and selecting "Debug". The icon is gray when disabled and green when enabled.

PHPStorm

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After creating the "docker" run configuration in PHPStorm (see above), "docker" will be one of the options available in the run configuration drop-down in the top toolbar.

Select docker in that dropdown to make it the active run configuration, however it's not necessary to start a debugging session.

Select Run > Start Listening for PHP Debug Connections to have PHPStorm listen for connections to the docker server, i.e. requests for "localhost" in a browser.

Request site content

Then in a browser make a request for http://localhost, or in a terminal window enter curl localhost. The IDE will automatically catch the request and break at any breakpoints.

Select Run > Break at first line in PHP scripts to catch all requests to the docker server, or place a breakpoint in the page of interest.

Uploading edits

Any changes to the source files in PHPStorm are immediately available on the server. The volumes directive in docker-compose.yml creates the links between the local source directories and the server directories.

See also

External links

• Zero-Configuration Debugging -- PHPStorm Documentation
• Docker Cookbook
• Xdebug Extension for PHP documentation