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dockerbuildpecl

Pass empty string (double quote) argument to dockerfile

My project wrapped by Docker and run in 2 environments: behind proxy or no proxy.

In this case, I use php:apache image and install ext via pecl, so I must set proxy manually

FROM php:apache

RUN pear config-set http_proxy $http_proxy
# RUN pecl install mongodb && docker-php-ext-enable mongodb

The $http_proxy arg will passed from docker-compose in 2 values: http://server:port or “” (double quote)

But when build the custom image in case “”, the $http_proxy arg was null, and show error in the config command

Step 4/4 : RUN pear config-set http_proxy $http_proxy

—> Running in 19b69d089ff2

config-set expects 2 or 3 parameters

Solution

  • Since it is a RUN command, you can add a test:

    docker build -t my_apache .  --build-arg http_proxy=....

    With a Dockerfile:

    ARG http_proxy
RUN if [ "x$http_proxy" != "x" ] ; then  pear config-set http_proxy $http_proxy; fi

    You actually don't need the ARG http_proxy as it is one of the predefined ones.