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+=============
+Configuration
+=============
+
+OpenStackClient is primarily configured using command line options and environment
+variables.  Most of those settings can also be placed into a configuration file to
+simplify managing multiple cloud configurations.
+
+There is a relationship between the global options, environment variables and
+keywords used in the configuration files that should make translation between
+these three areas simple.
+
+Most global options have a corresponding environment variable that may also be
+used to set the value. If both are present, the command-line option takes priority.
+The environment variable names are derived from the option name by dropping the
+leading dashes (--), converting each embedded dash (-) to an underscore (_), and
+converting to upper case.
+
+The keyword names in the configurations files are derived from the global option
+names by dropping the ``--os-`` prefix if present.
+
+Global Options
+--------------
+
+The :doc:`openstack manpage <man/openstack>` lists all of the global
+options recognized by OpenStackClient and the default authentication plugins.
+
+Environment Variables
+---------------------
+
+The :doc:`openstack manpage <man/openstack>` also lists all of the
+environment variables recognized by OpenStackClient and the default
+authentication plugins.
+
+Configuration Files
+-------------------
+
+clouds.yaml
+~~~~~~~~~~~
+
+:file:`clouds.yaml` is a configuration file that contains everything needed
+to connect to one or more clouds.  It may contain private information and
+is generally considered private to a user.
+
+OpenStackClient looks for a file called :file:`clouds.yaml` in the following
+locations:
+
+* current directory
+* :file:`~/.config/openstack`
+* :file:`/etc/openstack`
+
+The first file found wins.
+
+The keys match the :program:`openstack` global options but without the
+``--os-`` prefix.
+
+::
+
+    clouds:
+      devstack:
+        auth:
+          auth_url: http://192.168.122.10:35357/
+          project_name: demo
+          username: demo
+          password: 0penstack
+        region_name: RegionOne
+      ds-admin:
+        auth:
+          auth_url: http://192.168.122.10:35357/
+          project_name: admin
+          username: admin
+          password: 0penstack
+        region_name: RegionOne
+      infra:
+        cloud: rackspace
+        auth:
+          project_id: 275610
+          username: openstack
+          password: xyzpdq!lazydog
+        region_name: DFW,ORD,IAD
+
+In the above example, the ``auth_url`` for the ``rackspace`` cloud is taken
+from :file:`clouds-public.yaml` (see below).
+
+The first two entries are for two of the default users of the same DevStack
+cloud.
+
+The third entry is for a Rackspace Cloud Servers account.  It is equivalent
+to the following options if the ``rackspace`` entry in :file:`clouds-public.yaml`
+(below) is present:
+
+::
+
+    --os-auth-url https://identity.api.rackspacecloud.com/v2.0/
+    --os-project-id 275610
+    --os-username openstack
+    --os-password xyzpdq!lazydog
+    --os-region-name DFW
+
+and can be selected on the command line::
+
+    openstack --os-cloud infra server list
+
+Note that multiple regions are listed in the ``rackspace`` entry.  An otherwise
+identical configuration is created for each region.  If ``-os-region-name`` is not
+specified on the command line, the first region in the list is used by default.
+
+clouds-public.yaml
+~~~~~~~~~~~~~~~~~~
+
+:file:`clouds-public.yaml` is a configuration file that is intended to contain
+public information about clouds that are common across a large number of users.
+The idea is that :file:`clouds-public.yaml` could easily be shared among users
+to simplify public could configuration.
+
+Similar to :file:`clouds.yaml`, OpenStackClient looks for
+:file:`clouds-public.yaml` in the following locations:
+
+* current directory
+* :file:`~/.config/openstack`
+* :file:`/etc/openstack`
+
+The first file found wins.
+
+The keys here are referenced in :file:`clouds.yaml` ``cloud`` keys.  Anything
+that appears in :file:`clouds.yaml`
+
+::
+
+    public-clouds:
+      rackspace:
+        auth:
+          auth_url: 'https://identity.api.rackspacecloud.com/v2.0/'