How do I install XDebug on docker's official p

Question

I'm using wordpress:php7.1-fpm-alpine which is based on php:7.1-fpm-alpine (https://github.com/docker-library/wordpress/blob/master/php7.1/fpm-alpine/Dockerfile).

I've tried RUN pecl install xdebug-2.5.0 && docker-php-ext-enable xdebug

which results in an error when building:

Step 19/19 : RUN pecl install xdebug-2.5.0     && docker-php-ext-enable xdebug
 ---> Running in 52c988e12cb2
downloading xdebug-2.5.0.tgz ...
Starting to download xdebug-2.5.0.tgz (267,640 bytes)
........................................................done: 267,640 bytes
76 source files, building
running: phpize
Configuring for:
PHP Api Version:         20160303
Zend Module Api No:      20160303
Zend Extension Api No:   320160303
Cannot find autoconf. Please check your autoconf installation and the
$PHP_AUTOCONF environment variable. Then, rerun this script.

Answer 1

The following is sufficient for simply installing xdebug on that image:

FROM wordpress:php7.1-fpm-alpine

RUN apk add --no-cache $PHPIZE_DEPS \
    && pecl install xdebug-2.5.0 \
    && docker-php-ext-enable xdebug

Building that and then running from a shell inside the resulting image produces the following:

$ php -i | grep Xdebug
    with Xdebug v2.5.0, Copyright (c) 2002-2016, by Derick Rethans

Answer 2

Great answer @msanchez_aplyca. Although more correctly removing the build dependancies via apk would be:

RUN apk add --no-cache --virtual .build-deps $PHPIZE_DEPS \
    && pecl install xdebug-2.5.0 \
    && docker-php-ext-enable xdebug \
    && apk del -f .build-deps

Answer 3

If you are concerned about image size you can remove the dependencies:

FROM wordpress:php7.1-fpm-alpine 
RUN apk --update --no-cache add autoconf g++ make && \
    pecl install -f xdebug && \
    docker-php-ext-enable xdebug && \
    apk del --purge autoconf g++ make