title: Unable to locate package language-pack-en
body: <p>On my NodeJS server (running as docker image)... </p>
  
  <p><em>Dockerfile</em></p>
  
  <pre><code>FROM node:4.8-slim
  RUN apt-get update -y &amp;&amp; \
      apt-get install -yqq locales git
  </code></pre>
  
  <p>...there is no english locale installed:</p>
  
  <pre><code>RUN locale -a
  </code></pre>
  
  <p><em>gives me</em></p>
  
  <pre><code>C
  C.UTF-8
  POSIX
  </code></pre>
  
  <p>In my dockerfile I try to add the missing language</p>
  
  <pre><code>RUN apt-get install -y language-pack-en
  </code></pre>
  
  <p>But this gives me</p>
  
  <pre><code>Reading package lists...
  Building dependency tree...
  Reading state information...
  E: Unable to locate package language-pack-en
  </code></pre>
  
  <p>So how can I add the missing language pack?</p>
  
  <hr>
  
  <p><strong>Update</strong></p>
  
  <p>Using </p>
  
  <pre><code>sudo locale-gen en_US
  sudo locale-gen en_US.UTF-8
  sudo update-locale 
  </code></pre>
  
  <p>gives me this error:</p>
  
  <pre><code>perl: warning: Setting locale failed.
  perl: warning: Please check that your locale settings:
      LANGUAGE = "en_US:en",
      LC_ALL = "en_US.UTF-8",
      LANG = "en_US.UTF-8"
      are supported and installed on your system.
  perl: warning: Falling back to the standard locale ("C").
  locale: Cannot set LC_CTYPE to default locale: No such file or directory
  locale: Cannot set LC_MESSAGES to default locale: No such file or directory
  locale: Cannot set LC_COLLATE to 
  </code></pre>
  
  <p>default locale: No such file or directory</p>