title: Openstack "No hosts found to map to cell, exiting"
body: <p>I am running into problems with Devstack installation. I git cloned a fresh Devstack on my machine. Ran <code>./stack.sh</code> once, and hit the following problem.</p>
  
  <pre><code>2016-12-09 13:57:35.870 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] 344 -&gt; 345... 
  2016-12-09 13:57:36.225 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] done
  2016-12-09 13:57:36.226 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] 345 -&gt; 346... 
  2016-12-09 13:57:45.436 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] done
  2016-12-09 13:57:45.436 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] 346 -&gt; 347... 
  2016-12-09 13:57:47.680 INFO migrate.versioning.api [req-64697264-f3e0-4c8d-9fa1-19d9d3ceb744 None None] done
  No hosts found to map to cell, exiting.
  
  No hosts found to map to cell, exiting.
  +lib/nova:create_cell:1                    exit_trap
  +./stack.sh:exit_trap:487                  local r=1
  ++./stack.sh:exit_trap:488                  jobs -p
  +./stack.sh:exit_trap:488                  jobs=
  +./stack.sh:exit_trap:491                  [[ -n '' ]]
  +./stack.sh:exit_trap:497                  kill_spinner
  +./stack.sh:kill_spinner:383               '[' '!' -z '' ']'
  +./stack.sh:exit_trap:499                  [[ 1 -ne 0 ]]
  +./stack.sh:exit_trap:500                  echo 'Error on exit'
  Error on exit
  +./stack.sh:exit_trap:501                  generate-subunit 1481266214 5859 fail
  +./stack.sh:exit_trap:502                  [[ -z /opt/stack/logs ]]
  +./stack.sh:exit_trap:505                  /home/annakoppad/devstack/tools/worlddump.py -d /opt/stack/logs
  World dumping... see /opt/stack/logs/worlddump-2016-12-09-082802.txt for details
  +./stack.sh:exit_trap:511                  exit 1
  </code></pre>
  
  <p>Further, I did <code>./unstack.sh</code> to and <code>./clean.sh</code> to clean everything. The same error resulted.</p>
  
  <p>So, I tried two more options of using virtual environments using <code>pyvenv</code> and <code>virtualenv</code>. Both of them gave the same error that is shown below.</p>
  
  <pre><code>(mystack) annakoppad@annakoppad:~/Desktop/mystack/devstack$ ./stack.sh 
  + unset GREP_OPTIONS
  + unset LANG
  + unset LANGUAGE
  + LC_ALL=C
  + export LC_ALL
  + umask 022
  + PATH=/home/annakoppad/Desktop/mystack/bin:/home/annakoppad/bin:/home    /annakoppad/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/usr/local/sbin:/usr/sbin:/sbin
  +++ dirname ./stack.sh
  ++ cd .
  ++ pwd
  + TOP_DIR=/home/annakoppad/Desktop/mystack/devstack
  + NOUNSET=
  + [[ -n '' ]]
  ++ date +%s
  + DEVSTACK_START_TIME=1481289987
  + [[ -r /home/annakoppad/Desktop/mystack/devstack/.stackenv ]]
  + FILES=/home/annakoppad/Desktop/mystack/devstack/files
  + '[' '!' -d /home/annakoppad/Desktop/mystack/devstack/files ']'
  + '[' '!' -d /home/annakoppad/Desktop/mystack/devstack/inc ']'
  + '[' '!' -d /home/annakoppad/Desktop/mystack/devstack/lib ']'
  + [[ '' == \y ]]
  + [[ 1000 -eq 0 ]]
  + [[ -n /home/annakoppad/Desktop/mystack ]]
  + set +o xtrace
  You appear to be running under a python virtualenv.
  DevStack does not support this, as we may break the
  virtualenv you are currently in by modifying 
  external system-level components the virtualenv relies on.
  We recommend you use a separate virtual-machine if 
  you are worried about DevStack taking over your system.
  </code></pre>
  
  <p>Any pointers on how to overcome will be greatly appreciated.</p>
  
  <p>Thanks in advance.</p>