Varnish VCL configuration. It depends which configuration you will choose. IP addresses we are fetching from *.yml files. We explicitly set the static IP address to each Docker service.

Nginx:

```.host = "172.28.1.11";```    
```.port = "8000";```    

Apache:

```.host = "172.28.1.10";```    
```.port = "8080";```

How it looks like in the working environment. File - default.vcl

backend default {
    # IP was taken from nginx.yml, it is Nginx container IP address
    # nginx
    .host = "172.28.1.11";
    .port = "8000";

    # IP was taken from apache.yml, it is Apache container IP address
    # apache
    #.host = "172.28.1.10";
    #.port = "8080";
}    

• to build Docker images from scratch.

  docker-compose -f apache.yml up --build -d - run each container as a daemon. It means that the containers would run in the background completely detached from the shell.

  docker-compose -f apache.yml up --build - run containers with an interactive shell. It means that all log information from all the containers will be output to the shell (in case if a container is configured to output log information).

• startup existing configuration, in case, if all images have been already built

  docker-compose -f apache.yml up -d - run each container as a daemon.

  docker-compose -f apache.yml up - run containers with an interactive shell.

  docker-compose -f apache.yml start - start all the containers.

  docker-compose -f apache.yml stop - stop all the containers.

• by default, Apache will be started with PHP 5.6 version. But you have the possibility to switch between PHP versions (5.6 | 7.0 | 7.2) with a help of shell scripts. They reside inside the app_container running container by this path /tmp/shell. For PHP 7.2, if you need to install deprecated 'mcrypt' extension, instructions on how to do that you can find inside Apache Dockerfile

• to enable Xdebug - please check /tmp/shell folder inside the container (via a shell script). Container name app_container

• to build Docker images from scratch.

  docker-compose -f nginx.yml up --build -d - run each container as a daemon. It means that the containers would run in the background completely detached from the shell.

  docker-compose -f nginx.yml up --build - run containers with an interactive shell. It means that all log information from all the containers will be output to the shell (in case if a container is configured to output log information).

• startup existing configuration, in case, if all images have been already built

  docker-compose -f nginx.yml up -d - run each container as a daemon.

  docker-compose -f nginx.yml up - run containers with an interactive shell.

  docker-compose -f nginx.yml start - start all the containers.

  docker-compose -f nginx.yml stop - stop all the containers.

By default, the nginx.yml configuration will use PHP-FPM 7.0. But you have the possibility to switch between PHP-FPM versions (5.6 | 7.0 | 7.1 | 7.2).

To switch to another PHP-FPM version, for example, 7.1 you have to:

• build new PHP-FPM Docker image with a help of this command docker image build -t phpfpm_container:7.1 .

• use this newly created Docker image inside nginx.yml configuration.

Replace this part, which is used by default

    phpfpm:
        build: ./docker_configuration/php-fpm/7.0

to this one, after building a new PHP-FPM Docker image

    phpfpm:
        image: phpfpm_container:7.1

This procedure is the same for each PHP version.

• to enable Xdebug - you have to uncomment this line ;zend_extension=/usr/local/lib/php/extensions/no-debug-non-zts-20160303/xdebug.so

  file /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini

  inside phpfpm_container container and restart php-fpm service.