doc/source/faq.rst

===
FAQ
===

-  `General Questions <#general>`__
-  `Operation and Configuration <#ops_conf>`__
-  `Miscellaneous <#misc>`__

General Questions
=================

Q: Can I use DevStack for production?

    A: DevStack is targeted at developers and CI systems to use the
    raw upstream code.  It makes many choices that are not appropriate
    for production systems.

    Your best choice is probably to choose a `distribution of
    OpenStack
    <https://www.openstack.org/marketplace/distros>`__.

Q: Why a shell script, why not chef/puppet/...
    A: The script is meant to be read by humans (as well as ran by
    computers); it is the primary documentation after all. Using a
    recipe system requires everyone to agree and understand chef or
    puppet.

Q: I'd like to help!
    A: That isn't a question, but please do! The source for DevStack is
    at
    `git.openstack.org <https://git.openstack.org/cgit/openstack-dev/devstack>`__
    and bug reports go to
    `LaunchPad <http://bugs.launchpad.net/devstack/>`__. Contributions
    follow the usual process as described in the `developer
    guide <http://docs.openstack.org/infra/manual/developers.html>`__. This Sphinx
    documentation is housed in the doc directory.

Q: Why not use packages?
    A: Unlike packages, DevStack leaves your cloud ready to develop -
    checkouts of the code and services running in screen. However, many
    people are doing the hard work of packaging and recipes for
    production deployments.

Q: Why isn't $MY\_FAVORITE\_DISTRO supported?
    A: DevStack is meant for developers and those who want to see how
    OpenStack really works. DevStack is known to run on the
    distro/release combinations listed in ``README.md``. DevStack is
    only supported on releases other than those documented in
    ``README.md`` on a best-effort basis.

Q: Are there any differences between Ubuntu and Centos/Fedora support?
    A: Both should work well and are tested by DevStack CI.

Q: Why can't I use another shell?
    A: DevStack now uses some specific bash-ism that require Bash 4, such
    as associative arrays. Simple compatibility patches have been accepted
    in the past when they are not complex, at this point no additional
    compatibility patches will be considered except for shells matching
    the array functionality as it is very ingrained in the repo and project
    management.

Q: Can I test on OS/X?
   A: Some people have success with bash 4 installed via
   homebrew to keep running tests on OS/X.

Operation and Configuration
===========================

Q: Can DevStack handle a multi-node installation?
    A: Yes, see :doc:`multinode lab guide <guides/multinode-lab>`

Q: How can I document the environment that DevStack is using?
    A: DevStack includes a script (``tools/info.sh``) that gathers the
    versions of the relevant installed apt packages, pip packages and
    git repos. This is a good way to verify what Python modules are
    installed.

Q: How do I turn off a service that is enabled by default?
    A: Services can be turned off by adding ``disable_service xxx`` to
    ``local.conf`` (using ``n-vol`` in this example):

    ::

        disable_service n-vol

Q: Is enabling a service that defaults to off done with the reverse of the above?
    A: Of course!

    ::

        enable_service qpid

Q: How do I run a specific OpenStack milestone?
   A: OpenStack milestones have tags set in the git repo. Set the
   appropriate tag in the ``*_BRANCH`` variables in ``local.conf``.
   Swift is on its own release schedule so pick a tag in the Swift repo
   that is just before the milestone release. For example:

    ::

        [[local|localrc]]
        GLANCE_BRANCH=stable/kilo
        HORIZON_BRANCH=stable/kilo
        KEYSTONE_BRANCH=stable/kilo
        NOVA_BRANCH=stable/kilo
        GLANCE_BRANCH=stable/kilo
        NEUTRON_BRANCH=stable/kilo
        SWIFT_BRANCH=2.3.0

Q: What can I do about RabbitMQ not wanting to start on my fresh new VM?
    A: This is often caused by ``erlang`` not being happy with the
    hostname resolving to a reachable IP address. Make sure your
    hostname resolves to a working IP address; setting it to 127.0.0.1
    in ``/etc/hosts`` is often good enough for a single-node
    installation. And in an extreme case, use ``clean.sh`` to eradicate
    it and try again.

Q: How can I set up Heat in stand-alone configuration?
    A: Configure ``local.conf`` thusly:

    ::

        [[local|localrc]]
        HEAT_STANDALONE=True
        ENABLED_SERVICES=rabbit,mysql,heat,h-api,h-api-cfn,h-api-cw,h-eng
        KEYSTONE_SERVICE_HOST=<keystone-host>
        KEYSTONE_AUTH_HOST=<keystone-host>

Q: Why are my configuration changes ignored?
    A: You may have run into the package prerequisite installation
    timeout. ``tools/install_prereqs.sh`` has a timer that skips the
    package installation checks if it was run within the last
    ``PREREQ_RERUN_HOURS`` hours (default is 2). To override this, set
    ``FORCE_PREREQ=1`` and the package checks will never be skipped.

Miscellaneous
=============

Q: ``tools/fixup_stuff.sh`` is broken and shouldn't 'fix' just one version of packages.
    A: [Another not-a-question] No it isn't. Stuff in there is to
    correct problems in an environment that need to be fixed elsewhere
    or may/will be fixed in a future release. In the case of
    ``httplib2`` and ``prettytable`` specific problems with specific
    versions are being worked around. If later releases have those
    problems than we'll add them to the script. Knowing about the broken
    future releases is valuable rather than polling to see if it has
    been fixed.