title: Cannot install soap in docker container
body: <p>I have this issue with docker, I want to install soap in my container but it never works. If I run this image and try to <code>php -m</code> it will not show soap. If I run this image and do this:</p>
  
  <pre><code>apt-get install -y libxml++2.6-dev &amp;&amp; docker-php-ext-install soap
  </code></pre>
  
  <p>And <code>php -m</code>, then it works. I really don't understand this behavior and would love some help!</p>
  
  <pre><code>FROM php:5.6-cli
  
  RUN apt-get update -yqq
  RUN apt-get install git -yqq
  RUN apt-get install wget -yqq
  RUN apt-get install libssl-dev -yqq
  RUN apt-get install -yqq libfreetype6-dev libjpeg62-turbo-dev libmcrypt-dev libpng12-dev
  RUN apt-get clean -yqq
  
  RUN wget https://composer.github.io/installer.sig -O - -q | tr -d '\n' &gt; installer.sig
  RUN php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
  RUN php -r "if (hash_file('SHA384', 'composer-setup.php') === file_get_contents('installer.sig')) { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
  RUN php composer-setup.php
  RUN php -r "unlink('composer-setup.php'); unlink('installer.sig');"
  RUN mv composer.phar /usr/bin
  
  RUN docker-php-ext-install mysqli
  
  RUN docker-php-ext-install zip
  RUN docker-php-ext-install -j$(nproc) iconv mcrypt &amp;&amp; docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ --with-gif-dir=/usr/include/ &amp;&amp; docker-php-ext-install -j$(nproc) gd
  
  RUN pecl install mongo
  RUN echo "extension=mongo.so" &gt; /usr/local/etc/php/conf.d/ext-mongo.ini
  
  RUN pecl install mongodb
  RUN echo "extension=mongodb.so" &gt; /usr/local/etc/php/conf.d/ext-mongodb.ini
  
  ADD ssh_key /root/.ssh/id_rsa
  ADD ssh_key.pub /root/.ssh/id_rsa.pub
  RUN echo "    IdentityFile ~/.ssh/id_rsa" &gt;&gt; /etc/ssh/ssh_config
  RUN echo "Host *\n\tStrictHostKeyChecking no" &gt; /etc/ssh/ssh_config
  
  RUN apt-get install -y libxml++2.6-dev &amp;&amp; docker-php-ext-install soap
  </code></pre>
  
  <p><strong>Edit: here is the output of <code>php -m</code></strong></p>
  
  <pre><code>[PHP Modules]
  Core
  ctype
  curl
  date
  dom
  ereg
  fileinfo
  filter
  ftp
  gd
  hash
  iconv
  json
  libxml
  mbstring
  mcrypt
  mongo
  mongodb
  mysqli
  mysqlnd
  openssl
  pcre
  PDO
  pdo_sqlite
  Phar
  posix
  readline
  Reflection
  session
  SimpleXML
  SPL
  sqlite3
  standard
  tokenizer
  xml
  xmlreader
  xmlwriter
  zip
  zlib
  
  [Zend Modules]
  </code></pre>