Replace default configuration with my own in a Docker image - docker

Question

I am working in the following Dockerfile:
RUN apt-get update && \
DEBIAN_FRONTEND=noninteractive \
apt-get install -y \
curl \
apache2 \
php5 \
php5-cli \
libapache2-mod-php5 \
php5-gd \
php5-json \
php5-mcrypt \
php5-mysql \
php5-curl \
php5-memcached \
php5-mongo \
zend-framework
# Install Composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer && \
chown www-data /usr/local/bin/composer && composer --version
# Install usefull PHP tools
RUN composer global require sebastian/phpcpd && \
composer global require phpmd/phpmd && \
composer global require squizlabs/php_codesniffer
# Install xdebug after we install composer since it cause issues
# see https://getcomposer.org/doc/articles/troubleshooting.md#xdebug-impact-on-composer
RUN apt-get install -y php5-xdebug
As you may notice this install PHP 5.5.x and it comes with the default configuration which I would like to override with my own values.
I have the following directory structure:
docker-php55/
├── container-files
│   ├── config
│   │   └── init
│   │   └── vhost_default
│   └── etc
│   └── php.d
│   ├── zz-php-directories.ini
│   └── zz-php.ini
├── Dockerfile
├── LICENSE
├── README.md
└── run
The files zz-php-directories.ini and zz-php.ini are my configurations that I should write to /etc/php5/apache2/php.ini upon image creation. The content of the files is the following:
zz-php.ini
; Basic configuration override
expose_php = Off
memory_limit = 512M
post_max_size = 128M
upload_max_filesize = 128M
date.timezone = UTC
max_execution_time = 120
; Error reporting
display_errors = stderr
display_startup_errors = Off
error_reporting = E_ALL
; A bit of performance tuning
realpath_cache_size = 128k
; OpCache tuning
opcache.max_accelerated_files = 32000
; Temporarily disable using HUGE PAGES by OpCache.
; This should improve performance, but requires appropriate OS configuration
; and for now it often results with some weird PHP warning:
; PHP Warning: Zend OPcache huge_code_pages: madvise(HUGEPAGE) failed: Invalid argument (22) in Unknown on line 0
opcache.huge_code_pages=0
; Xdebug
[Xdebug]
xdebug.remote_enable = true
xdebug.remote_host = "192.168.3.1" // this IP should be the host IP
xdebug.remote_port = "9001"
xdebug.idekey = "XDEBUG_PHPSTORM"
zz-php-directories.ini
; Configure temp path locations
sys_temp_dir = /data/tmp/php
upload_tmp_dir = /data/tmp/php/uploads
session.save_path = /data/tmp/php/sessions
uploadprogress.file.contents_template = "/data/tmp/php/upload_contents_%s"
uploadprogress.file.filename_template = "/data/tmp/php/upt_%s.txt"
How do I override the default php.ini parameters on the image with the ones on those files upon image creation?
EDIT: Improve the question
To leave an example, zz-php.ini is a local file placed in my laptop|PC. As soon as I install PHP in the image it comes with a default configuration file, this mean I should have a file under /etc/php5/apache2/php.ini.
This default configuration file already has default values like for example: expose_php = On (again this is the default, others comes as ;realpath_cache_size =) so what I want to do is to change the value for the default file with the value from my file, in other words:
default (as in /etc/php5/apache2/php.ini) expose_php = On
override (as in zz-php.ini) expose_php = Off
At the end I should have the values from zz-php.ini overwrited in /etc/php5/apache2/php.ini
As for the host IP address I think I could use a ENV var and pass to the build as an argument, I am right? If no, then how would you get the host IP address needed for that setup?

Answer 1

That's two questions.
1) Just use the COPY instruction to copy your local php.ini into the image location. Eg:
COPY php.ini /etc/php5/apache2/php.ini
2) You don't want to hardcode any ip into your image. That needs to be done when the container is started. The standard way of doing this with docker is to specify an environment variable like HOST_IP and you use a shell script to make the modifications on the container at start time. For instance:
Your inject.sh script:
#!/usr/bin/bash
sed -i -E "s/xdebug.remote_host.*/xdebug.remote_host=$HOST_IP/" /etc/php5/apache2/php.ini
You need to add the inject.sh file to your image when you build it.
COPY inject.sh /usr/local/bin/
Then you can initialize and start your container as follow:
docker run -e HOST_IP=53.62.10.12 mycontainer bash -c "inject.sh && exec myphpapp"
The exec is needed to make sure the myphpapp becomes the main process of the container (ie: it has PID 1) otherwise it won't receive kill commands (like Ctrl-C).