Docker PHP5.6 Call to undefined function bindtextdomain()

Problem:

I have a Docker compose with an nginx service and a PHP service. When I try to open a page of my dev project, I encounter this error:

Fatal error: Call to undefined function bindtextdomain() in /usr/share/nginx/html/some_project/some_path/Bootstrap.php on line 16

I saw that is a problem of a missing dependency: php-gettext.

My configuration:

In my Dockerfile, I try to install it:

FROM php:5.6.30-fpm
MAINTAINER DarckCrystale "xxx@xxx.xx"

# Here I try to install the php-gettext extension
# but it does not work
RUN apt-get update && apt-get install -y php-gettext gettext

# Setup PHP configuration
ADD php.ini /usr/local/etc/php/conf.d/php.ini

In my php.ini, I load it:

extension=gettext.so

Other information:

When I run in my container

php -i | grep extension_dir

I have this message displayed:

PHP Warning: PHP Startup: Unable to load dynamic library '/usr/local/lib/php/extensions/no-debug-non-zts-20131226/gettext.so' - /usr/local/lib/php/extensions/no-debug-non-zts-20131226/gettext.so: cannot open shared object file: No such file or directory in Unknown on line 0

What it seems to be to me:

I think

RUN apt-get update && apt-get install -y php-gettext gettext

does not install the php-gettext extension. I don't know why. I think this is a PHP Dockerized specific problem.

Solution

So, after struggle, I finally found how to install this extension in the PHP container!

How to solve this problem?

Use docker-php-ext-install instead of apt-get install in the Dockerfile:

FROM php:5.6.30-fpm
MAINTAINER DarckCrystale "xxx@xxx.xx"

# Here I install the php-gettext extension
# and it works! :D
RUN docker-php-ext-install gettext

# Setup PHP configuration
ADD php.ini /usr/local/etc/php/conf.d/php.ini

What is the problem?

PHP container have a specific way to install PHP extensions:

How to install more PHP extensions

We provide the helper scripts docker-php-ext-configure, docker-php-ext-install, and docker-php-ext-enable to more easily install PHP extensions.

So php-gettext extension installation seems to work only using provided scripts.