title: How do I install XDebug on docker's official php-fpm-alpine image?
body: <p>I'm using <code>wordpress:php7.1-fpm-alpine</code> which is based on <code>php:7.1-fpm-alpine</code> (<a href="https://github.com/docker-library/wordpress/blob/master/php7.1/fpm-alpine/Dockerfile" rel="noreferrer">https://github.com/docker-library/wordpress/blob/master/php7.1/fpm-alpine/Dockerfile</a>).</p>
  
  <p>I've tried <code>RUN pecl install xdebug-2.5.0   &amp;&amp; docker-php-ext-enable xdebug</code></p>
  
  <p>which results in an error when building: </p>
  
  <pre><code>Step 19/19 : RUN pecl install xdebug-2.5.0     &amp;&amp; docker-php-ext-enable xdebug
   ---&gt; 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.
  </code></pre>