title: How to add users to Docker container?
body: <p>I have a docker container with some processes (uwsgi and celery) running inside. I want to create a celery user and a uwsgi user for these processes as well as a worker group that they will both belong to, in order to assign permissions. </p>
  
  <p>I tried adding <code>RUN adduser uwsgi</code> and <code>RUN adduser celery</code> to my Dockerfile, but this is causing problems, since these commands prompt for input (I've posted the responses from the build below). </p>
  
  <p>What is the best way to add users to a Docker container so as to set permissions for workers running in the container?</p>
  
  <p>My Docker image is built from the official Ubuntu14.04 base.</p>
  
  <p>Here is the output from the Dockerfile when the adduser commands are run:</p>
  
  <pre><code>Adding user `uwsgi' ...
  Adding new group `uwsgi' (1000) ... 
  Adding new user `uwsgi' (1000) with group `uwsgi' ... 
  Creating home directory `/home/uwsgi' ...
  Copying files from `/etc/skel' ... 
  [91mEnter new UNIX password: Retype new UNIX password: [0m 
  [91mpasswd: Authentication token manipulation error
  passwd: password unchanged
  [0m 
  [91mUse of uninitialized value $answer in chop at /usr/sbin/adduser line 563.
  [0m 
  [91mUse of uninitialized value $answer in pattern match (m//) at /usr/sbin/adduser line 564.
  [0m 
  Try again? [y/N] 
  Changing the user information for uwsgi
  Enter the new value, or press ENTER for the default
      Full Name []: 
  Room Number []:     Work Phone []:  Home Phone []:  Other []: 
  [91mUse of uninitialized value $answer in chop at /usr/sbin/adduser line 589.
  [0m 
  [91mUse of uninitialized value $answer in pattern match (m//) at /usr/sbin/adduser line 590.
  [0m 
  Is the information correct? [Y/n] 
  ---&gt; 258f2f2f13df 
  Removing intermediate container 59948863162a 
  Step 5 : RUN adduser celery 
  ---&gt; Running in be06f1e20f64 
  Adding user `celery' ...
  Adding new group `celery' (1001) ... 
  Adding new user `celery' (1001) with group `celery' ... 
  Creating home directory `/home/celery' ...
  Copying files from `/etc/skel' ... 
  [91mEnter new UNIX password: Retype new UNIX password: [0m 
  [91mpasswd: Authentication token manipulation error
  passwd: password unchanged
  [0m 
  [91mUse of uninitialized value $answer in chop at /usr/sbin/adduser line 563.
  [0m 
  [91mUse of uninitialized value $answer in pattern match (m//) at /usr/sbin/adduser line 564.
  [0m 
  Try again? [y/N] 
  Changing the user information for celery
  Enter the new value, or press ENTER for the default
      Full Name []:   Room Number []:     Work Phone []: 
  Home Phone []:  Other []: 
  [91mUse of uninitialized value $answer in chop at /usr/sbin/adduser line 589.
  [0m 
  [91mUse of uninitialized value $answer in pattern match (m//) at /usr/sbin/adduser line 590.
  [0m 
  Is the information correct? [Y/n] 
  </code></pre>