=================
Command Structure
=================

OpenStackClient has a consistent and predictable format for all of its commands.

Commands take the form::

    openstack [<global-options>] <object-1> <action> [<object-2>] [<command-arguments>]

* All long options names begin with two dashes (``--``) and use a single dash
  (``-``) internally between words (``--like-this``).  Underscores (``_``) are
  not used in option names.


Global Options
--------------

Global options are global in the sense that they apply to every command
invocation regardless of action to be performed. They include authentication
credentials and API version selection. 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.

For example, the default value of ``--os-username`` can be set by defining
the environment variable ``OS_USERNAME``.


Command Object(s) and Action
----------------------------

Commands consist of an object described by one or more words followed by
an action.  Commands that require two objects have the primary object ahead
of the action and the secondary object after the action. Any positional
arguments identifying the objects shall appear in the same order as the
objects.  In badly formed English it is expressed as "(Take) object1
(and perform) action (using) object2 (to it)."

::

    <object-1> <action> <object-2>

Examples:

.. code-block:: bash

    $ group add user <group> <user>

    $ volume type list   # 'volume type' is a two-word single object


Command Arguments and Options
-----------------------------

Each command may have its own set of options distinct from the global options.
They follow the same style as the global options and always appear between
the command and any positional arguments the command requires.


Objects
-------

The objects consist of one or more words to compose a unique name.
Occasionally when multiple APIs have a common name with common
overlapping purposes there will be options to select which object to use, or
the API resources will be merged, as in the ``quota`` object that has options
referring to both Compute and Volume quotas.

* ``access token``: (**Identity**) long-lived OAuth-based token
* ``availability zone``: (**Compute**) a logical partition of hosts or volume services
* ``aggregate``: (**Compute**) a grouping of servers
* ``backup``: (**Volume**) a volume copy
* ``catalog``: (**Identity**) service catalog
* ``console log``: (**Compute**) server console text dump
* ``console url``: (**Compute**) server remote console URL
* ``consumer``: (**Identity**) OAuth-based delegatee
* ``container``: (**Object Store**) a grouping of objects
* ``credentials``: (**Identity**) specific to identity providers
* ``domain``: (**Identity**) a grouping of projects
* ``ec2 cedentials``: (**Identity**) AWS EC2-compatible credentials
* ``endpoint``: (**Identity**) the base URL used to contact a specific service
* ``extension``: (**Compute**, **Identity**, **Volume**) OpenStack server API extensions
* ``federation protocol``: (**Identity**) the underlying protocol used while federating identities
* ``flavor``: (**Compute**) predefined server configurations: ram, root disk, etc
* ``group``: (**Identity**) a grouping of users
* ``host``: Compute - the physical computer running a hypervisor
* ``hypervisor``: (**Compute**) the virtual machine manager
* ``hypervisor stats``: (**Compute**) hypervisor statistics over all compute nodes
* ``identity provider``: (**Identity**) a source of users and authentication
* ``image``: (**Image**) a disk image
* ``ip fixed``: Compute, Network - an internal IP address assigned to a server
* ``ip floating``: Compute, Network - a public IP address that can be mapped to a server
* ``keypair``: (**Compute**) an SSH public key
* ``limits``: (**Compute**, **Volume**) resource usage limits
* ``mapping``: (**Identity**) a definition to translate identity provider attributes to Identity concepts
* ``module``: internal - installed Python modules in the OSC process
* ``network``: Network - a virtual network for connecting servers and other resources
* ``object``: (**Object Store**) a single file in the Object Store
* ``policy``: (**Identity**) determines authorization
* ``project``: (**Identity**) owns a group of resources
* ``quota``: (**Compute**, **Volume**) resource usage restrictions
* ``region``: (**Identity**) a subset of an OpenStack deployment
* ``request token``: (**Identity**) temporary OAuth-based token
* ``role``: (**Identity**) a policy object used to determine authorization
* ``role assignment``: (**Identity**) a relationship between roles, users or groups, and domains or projects
* ``security group``: Compute, Network - groups of network access rules
* ``security group rule``: Compute, Network - the individual rules that define protocol/IP/port access
* ``server``: (**Compute**) virtual machine instance
* ``server image``: (**Compute**) saved server disk image
* ``service``: (**Identity**) a cloud service
* ``service provider``: (**Identity**) a resource that consumes assertions from an ``identity provider``
* ``snapshot``: (**Volume**) a point-in-time copy of a volume
* ``token``: (**Identity**) a bearer token managed by Identity service
* ``usage``: (**Compute**) display host resources being consumed
* ``user``: (**Identity**) individual cloud resources users
* ``user role``: (**Identity**) roles assigned to a user
* ``volume``: (**Volume**) block volumes
* ``volume type``: (**Volume**) deployment-specific types of volumes available

Actions
-------

The actions used by OpenStackClient are defined below to provide a consistent
meaning to each action. Many of them have logical opposite actions.
Those actions with an opposite action are noted in parens if applicable.

* ``authorize`` - authorize a token (used in OAuth)
* ``add`` (``remove``) - add some object to a container object; the command
  is built in the order of ``container add object <container> <object>``,
  the positional arguments appear in the same order
* ``create`` (``delete``) - create a new occurrence of the specified object
* ``delete`` (``create``) - delete a specific occurrence of the specified object
* ``issue`` (``revoke``) - issue a token
* ``list`` - display summary information about multiple objects
* ``lock`` (``unlock``)
* ``migrate`` - move a server to a different host; ``--live`` performs a
  live migration if possible
* ``pause`` (``unpause``) - stop a server and leave it in memory
* ``reboot`` - forcibly reboot a server
* ``rebuild`` - rebuild a server using (most of) the same arguments as in the original create
* ``remove`` (``add``) - remove an object from a group of objects
* ``rescue`` (``unrescue``) - reboot a server in a special rescue mode allowing access to the original disks
* ``resize`` - change a server's flavor
* ``resume`` (``suspend``) - return a suspended server to running state
* ``revoke`` (``issue``) - revoke a token
* ``save`` - download an object locally
* ``set`` (``unset``) - set a property on the object, formerly called metadata
* ``show`` - display detailed information about the specific object
* ``suspend`` (``resume``) - stop a server and save to disk freeing memory
* ``unlock`` (``lock``)
* ``unpause`` (``pause``) - return a paused server to running state
* ``unrescue`` (``rescue``) - return a server to normal boot mode
* ``unset`` (``set``) - remove an attribute of the object


Implementation
--------------

The command structure is designed to support seamless addition of plugin
command modules via ``setuptools`` entry points.  The plugin commands must
be subclasses of Cliff's ``command.Command`` object.  See :doc:`plugins` for
more information.


Command Entry Points
--------------------

Commands are added to the client using ``setuptools`` entry points in ``setup.cfg``.
There is a single common group ``openstack.cli`` for commands that are not versioned,
and a group for each combination of OpenStack API and version that is
supported.  For example, to support Identity API v3 there is a group called
``openstack.identity.v3`` that contains the individual commands.  The command
entry points have the form::

    action_object = fully.qualified.module.vXX.object:ActionObject

For example, the ``list user`` command for the Identity API is identified in
``setup.cfg`` with::

    openstack.identity.v3 =
        # ...
        list_user = openstackclient.identity.v3.user:ListUser
        # ...
