openstack/glance
Code Issues Proposed changes

Documentation cleanup. Splits out index.rst into multiple section docs.

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jaypipes@gmail.com 2010-12-22 12:38:54 -05:00
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# Makefile for Sphinx documentation
#
# You can set these variables from the command line.
SPHINXOPTS =
SPHINXBUILD = sphinx-build
SPHINXSOURCE = source
PAPER =
BUILDDIR = build
# Internal variables.
PAPEROPT_a4 = -D latex_paper_size=a4
PAPEROPT_letter = -D latex_paper_size=letter
ALLSPHINXOPTS = -d $(BUILDDIR)/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) $(SPHINXSOURCE)
.PHONY: help clean html dirhtml pickle json htmlhelp qthelp latex changes linkcheck doctest
.DEFAULT_GOAL = html
help:
@echo "Please use \`make <target>' where <target> is one of"
@echo " html to make standalone HTML files"
@echo " dirhtml to make HTML files named index.html in directories"
@echo " pickle to make pickle files"
@echo " json to make JSON files"
@echo " htmlhelp to make HTML files and a HTML help project"
@echo " qthelp to make HTML files and a qthelp project"
@echo " latex to make LaTeX files, you can set PAPER=a4 or PAPER=letter"
@echo " changes to make an overview of all changed/added/deprecated items"
@echo " linkcheck to check all external links for integrity"
@echo " doctest to run all doctests embedded in the documentation (if enabled)"
clean:
-rm -rf $(BUILDDIR)/*
-rm -rf nova.sqlite
if [ -f .autogenerated ] ; then \
cat .autogenerated | xargs rm ; \
rm .autogenerated ; \
fi
html:
$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
dirhtml:
$(SPHINXBUILD) -b dirhtml $(ALLSPHINXOPTS) $(BUILDDIR)/dirhtml
@echo
@echo "Build finished. The HTML pages are in $(BUILDDIR)/dirhtml."
pickle:
$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDDIR)/pickle
@echo
@echo "Build finished; now you can process the pickle files."
json:
$(SPHINXBUILD) -b json $(ALLSPHINXOPTS) $(BUILDDIR)/json
@echo
@echo "Build finished; now you can process the JSON files."
htmlhelp:
$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
@echo
@echo "Build finished; now you can run HTML Help Workshop with the" \
".hhp project file in $(BUILDDIR)/htmlhelp."
qthelp:
$(SPHINXBUILD) -b qthelp $(ALLSPHINXOPTS) $(BUILDDIR)/qthelp
@echo
@echo "Build finished; now you can run "qcollectiongenerator" with the" \
".qhcp project file in $(BUILDDIR)/qthelp, like this:"
@echo "# qcollectiongenerator $(BUILDDIR)/qthelp/nova.qhcp"
@echo "To view the help file:"
@echo "# assistant -collectionFile $(BUILDDIR)/qthelp/nova.qhc"
latex:
$(SPHINXBUILD) -b latex $(ALLSPHINXOPTS) $(BUILDDIR)/latex
@echo
@echo "Build finished; the LaTeX files are in $(BUILDDIR)/latex."
@echo "Run \`make all-pdf' or \`make all-ps' in that directory to" \
"run these through (pdf)latex."
changes:
$(SPHINXBUILD) -b changes $(ALLSPHINXOPTS) $(BUILDDIR)/changes
@echo
@echo "The overview file is in $(BUILDDIR)/changes."
linkcheck:
$(SPHINXBUILD) -b linkcheck $(ALLSPHINXOPTS) $(BUILDDIR)/linkcheck
@echo
@echo "Link check complete; look for any errors in the above output " \
"or in $(BUILDDIR)/linkcheck/output.txt."
doctest:
$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDDIR)/doctest
@echo "Testing of doctests in the sources finished, look at the " \
"results in $(BUILDDIR)/doctest/output.txt."

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{% extends "sphinxdoc/layout.html" %}
{% set css_files = css_files + ['_static/tweaks.css'] %}
{% set script_files = script_files + ['_static/jquery.tweet.js'] %}
{% block extrahead %}
<script type='text/javascript'>
$(document).ready(function(){
$("#twitter_feed").tweet({
username: "openstack",
query: "from:openstack",
avatar_size: 32,
count: 10,
loading_text: "loading tweets..."
});
});
</script>
{% endblock %}
{%- macro sidebar() %}
{%- if not embedded %}{% if not theme_nosidebar|tobool %}
<div class="sphinxsidebar">
<div class="sphinxsidebarwrapper">
{%- block sidebarlogo %}
{%- if logo %}
<p class="logo"><a href="{{ pathto(master_doc) }}">
<img class="logo" src="{{ pathto('_static/' + logo, 1) }}" alt="Logo"/>
</a></p>
{%- endif %}
{%- endblock %}
{%- block sidebartoc %}
{%- if display_toc %}
<h3><a href="{{ pathto(master_doc) }}">{{ _('Table Of Contents') }}</a></h3>
{{ toc }}
{%- endif %}
{%- endblock %}
{%- block sidebarrel %}
{%- if prev %}
<h4>{{ _('Previous topic') }}</h4>
<p class="topless"><a href="{{ prev.link|e }}"
title="{{ _('previous chapter') }}">{{ prev.title }}</a></p>
{%- endif %}
{%- if next %}
<h4>{{ _('Next topic') }}</h4>
<p class="topless"><a href="{{ next.link|e }}"
title="{{ _('next chapter') }}">{{ next.title }}</a></p>
{%- endif %}
{%- endblock %}
{%- block sidebarsourcelink %}
{%- if show_source and has_source and sourcename %}
<h3>{{ _('This Page') }}</h3>
<ul class="this-page-menu">
<li><a href="{{ pathto('_sources/' + sourcename, true)|e }}"
rel="nofollow">{{ _('Show Source') }}</a></li>
</ul>
{%- endif %}
{%- endblock %}
{%- if customsidebar %}
{% include customsidebar %}
{%- endif %}
{%- block sidebarsearch %}
{%- if pagename != "search" %}
<div id="searchbox" style="display: none">
<h3>{{ _('Quick search') }}</h3>
<form class="search" action="{{ pathto('search') }}" method="get">
<input type="text" name="q" size="18" />
<input type="submit" value="{{ _('Go') }}" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
<p class="searchtip" style="font-size: 90%">
{{ _('Enter search terms or a module, class or function name.') }}
</p>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
{%- endif %}
{%- if pagename == "index" %}
<h3>{{ _('Twitter Feed') }}</h3>
<div id="twitter_feed" class='twitter_feed'></div>
{%- endif %}
{%- endblock %}
</div>
</div>
{%- endif %}{% endif %}
{%- endmacro %}

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[theme]
inherit = sphinxdoc
stylesheet = sphinxdoc.css
pygments_style = friendly

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..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Using Glance Programmatically with Glance's Client
==================================================
While it is perfectly acceptable to issue HTTP requests directly to Glance
via its RESTful API, sometimes it is better to be able to access and modify
image resources via a client class that removes some of the complexity and
tedium of dealing with raw HTTP requests.
Glance includes a client class for just this purpose. You can retrieve
metadata about an image, change metadata about an image, remove images, and
of course retrieve an image itself via this client class.
Below are some examples of using Glance's Client class. We assume that
there is a Glance server running at the address `glance.openstack.org`
on port `9292`.
Requesting a List of Public VM Images
-------------------------------------
We want to see a list of available virtual machine images that the Glance
server knows about.
Using Glance's Client, we can do this using the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_images()
Requesting Detailed Metadata on Public VM Images
------------------------------------------------
We want to see more detailed information on available virtual machine images
that the Glance server knows about.
Using Glance's Client, we can do this using the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_images_detailed()
Requesting Detailed Metadata on a Specific Image
------------------------------------------------
We want to see detailed information for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can use the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_image_meta("http://glance.openstack.org/images/1")
Retrieving a Virtual Machine Image
----------------------------------
We want to retrieve that actual raw data for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get both the metadata about the
first public image returned and its image data, we can use the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
meta, image_file = c.get_image("http://glance.openstack.org/images/1")
print meta
f = open('some_local_file', 'wb')
for chunk in image_file:
f.write(chunk)
f.close()
Note that the return from Client.get_image() is a tuple of (`metadata`, `file`)
where `metadata` is a mapping of metadata about the image and `file` is a
generator that yields chunks of image data.
Adding a New Virtual Machine Image
----------------------------------
We have created a new virtual machine image in some way (created a
"golden image" or snapshotted/backed up an existing image) and we
wish to do two things:
* Store the disk image data in Glance
* Store metadata about this image in Glance
We can do the above two activities in a single call to the Glance client.
Assuming, like in the examples above, that a Glance API server is running
at `glance.openstack.org`, we issue a call to `glance.client.Client.add_image`.
The method signature is as follows::
glance.client.Client.add_image(image_meta, image_data=None)
The `image_meta` argument is a mapping containing various image metadata. The
`image_data` argument is the disk image data.
The list of metadata that `image_meta` can contain are listed below.
* `name`
This key/value is required. Its value should be the name of the image.
Note that the name of an image *is not unique to a Glance node*. It
would be an unrealistic expectation of users to know all the unique
names of all other user's images.
* `id`
This key/value is optional.
When present, Glance will use the supplied identifier for the image.
If the identifier already exists in that Glance node, then a
`glance.common.exception.Duplicate` will be raised.
When this key/value is *not* present, Glance will generate an identifier
for the image and return this identifier in the response (see below)
* `store`
This key/value is optional. Valid values are one of `file` or `swift`
When present, Glance will attempt to store the disk image data in the
backing store indicated by the value. If the Glance node does not support
the backing store, Glance will raise a `glance.common.exception.BadRequest`
When not present, Glance will store the disk image data in the backing
store that is marked default. See the configuration option `default_store`
for more information.
* `type`
This key/values is required. Valid values are one of `kernel`, `machine`,
`raw`, or `ramdisk`.
* `size`
This key/value is optional.
When present, Glance assumes that the expected size of the request body
will be the value. If the length in bytes of the request body *does not
match* the value, Glance will raise a `glance.common.exception.BadRequest`
When not present, Glance will calculate the image's size based on the size
of the request body.
* `is_public`
This key/value is optional.
When present, Glance converts the value to a boolean value, so "on, 1, true"
are all true values. When true, the image is marked as a public image,
meaning that any user may view its metadata and may read the disk image from
Glance.
When not present, the image is assumed to be *not public* and specific to
a user.
* `properties`
This key/value is optional.
When present, the value is assumed to be a mapping of free-form key/value
attributes to store with the image.
For example, if the following is the value of the `properties` key in the
`image_meta` argument::
{'distro': 'Ubuntu 10.10'}
Then a key/value pair of "distro"/"Ubuntu 10.10" will be stored with the
image in Glance.
There is no limit on the number of free-form key/value attributes that can
be attached to the image with `properties`. However, keep in mind that there
is a 8K limit on the size of all HTTP headers sent in a request and this
number will effectively limit the number of image properties.
As a complete example, the following code would add a new machine image to
Glance::
from glance.client import Client
c = Client("glance.openstack.org", 9292)
meta = {'name': 'Ubuntu 10.10 5G',
'type': 'machine',
'is_public': True,
'properties': {'distro': 'Ubuntu 10.10'}}
new_meta = c.add_image(meta, open('/path/to/image.tar.gz'))
print 'Stored image. Got identifier: %s' % new_meta['id']

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..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Getting Involved
================
The Glance community is a very friendly group and there are places online to join in with the
community. Feel free to ask questions. This document points you to some of the places where you can
communicate with people.
How to Join the OpenStack Community
-----------------------------------
Our community welcomes all people interested in open source cloud computing, and there are no formal
membership requirements. The best way to join the community is to talk with others online or at a meetup
and offer contributions through Launchpad, the wiki, or blogs. We welcome all types of contributions,
from blueprint designs to documentation to testing to deployment scripts.
Contributing Code
-----------------
To contribute code, sign up for a Launchpad account and sign a contributor license agreement,
available on the `<http://wiki.openstack.org/CLA>`_. Once the CLA is signed you
can contribute code through the Bazaar version control system which is related to your Launchpad account.
#openstack on Freenode IRC Network
----------------------------------
There is a very active chat channel at `<irc://freenode.net/#openstack>`_. This
is usually the best place to ask questions and find your way around. IRC stands for Internet Relay
Chat and it is a way to chat online in real time. You can also ask a question and come back to the
log files to read the answer later. Logs for the #openstack IRC channel are stored at
`<http://eavesdrop.openstack.org/irclogs/>`_.
OpenStack Wiki
--------------
The wiki is a living source of knowledge. It is edited by the community, and
has collections of links and other sources of information. Typically the pages are a good place
to write drafts for specs or documentation, describe a blueprint, or collaborate with others.
`OpenStack Wiki <http://wiki.openstack.org/>`_
Glance on Launchpad
-------------------
Launchpad is a code hosting service that hosts the Glance source code. From
Launchpad you can report bugs, ask questions, and register blueprints (feature requests).
* `Learn about how to use bzr with launchpad <http://wiki.openstack.org/LifeWithBzrAndLaunchpad>`_
* `Launchpad Glance Page <http://launchpad.net/glance>`_
OpenStack Blog
--------------
The OpenStack blog includes a weekly newsletter that aggregates OpenStack news
from around the internet, as well as providing inside information on upcoming
events and posts from OpenStack contributors.
`OpenStack Blog <http://openstack.org/blog>`_
See also: `Planet OpenStack <http://planet.openstack.org/>`_, aggregating blogs
about OpenStack from around the internet into a single feed. If you'd like to contribute to this blog
aggregation with your blog posts, there are instructions for `adding your blog <http://wiki.openstack.org/AddingYourBlog>`_.
Twitter
-------
Because all the cool kids do it: `@openstack <http://twitter.com/openstack>`_. Also follow the
`#openstack <http://search.twitter.com/search?q=%23openstack>`_ tag for relevant tweets.

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..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
The Glance REST API
===================
Glance has a RESTful API that exposes both metadata about registered virtual
machine images and the image data itself.
A host that runs the `bin/glance-api` service is said to be a *Glance API
Server*.
Assume there is a Glance API server running at the URL
http://glance.openstack.org.
Let's walk through how a user might request information from this server.
Requesting a List of Public VM Images
-------------------------------------
We want to see a list of available virtual machine images that the Glance
server knows about.
We issue a `GET` request to http://glance.openstack.org/images/ to retrieve
this list of available *public* images. The data is returned as a JSON-encoded
mapping in the following format::
{'images': [
{'uri': 'http://glance.openstack.org/images/1',
'name': 'Ubuntu 10.04 Plain',
'type': 'kernel',
'size': '5368709120'}
...]}
Notes:
* All images returned from the above `GET` request are *public* images
Requesting Detailed Metadata on Public VM Images
------------------------------------------------
We want to see more detailed information on available virtual machine images
that the Glance server knows about.
We issue a `GET` request to http://glance.openstack.org/images/detail to
retrieve this list of available *public* images. The data is returned as a
JSON-encoded mapping in the following format::
{'images': [
{'uri': 'http://glance.openstack.org/images/1',
'name': 'Ubuntu 10.04 Plain 5GB',
'type': 'kernel',
'size': '5368709120',
'store': 'swift',
'created_at': '2010-02-03 09:34:01',
'updated_at': '2010-02-03 09:34:01',
'deleted_at': '',
'status': 'available',
'is_public': True,
'properties': {'distro': 'Ubuntu 10.04 LTS'}},
...]}
Notes:
* All images returned from the above `GET` request are *public* images
* All timestamps returned are in UTC
* The `updated_at` timestamp is the timestamp when an image's metadata
was last updated, not it's image data, as all image data is immutable
once stored in Glance
* The `properties` field is a mapping of free-form key/value pairs that
have been saved with the image metadata
Requesting Detailed Metadata on a Specific Image
------------------------------------------------
We want to see detailed information for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can issue a `HEAD` request to the Glance
server for the image's URI.
We issue a `HEAD` request to http://glance.openstack.org/images/1 to
retrieve complete metadata for that image. The metadata is returned as a
set of HTTP headers that begin with the prefix `x-image-meta-`. The
following shows an example of the HTTP headers returned from the above
`HEAD` request::
x-image-meta-uri http://glance.openstack.org/images/1
x-image-meta-name Ubuntu 10.04 Plain 5GB
x-image-meta-type kernel
x-image-meta-size 5368709120
x-image-meta-store swift
x-image-meta-created_at 2010-02-03 09:34:01
x-image-meta-updated_at 2010-02-03 09:34:01
x-image-meta-deleted_at
x-image-meta-status available
x-image-meta-is_public True
x-image-meta-property-distro Ubuntu 10.04 LTS
Notes:
* All timestamps returned are in UTC
* The `x-image-meta-updated_at` timestamp is the timestamp when an
image's metadata was last updated, not it's image data, as all
image data is immutable once stored in Glance
* There may be multiple headers that begin with the prefix
`x-image-meta-property-`. These headers are free-form key/value pairs
that have been saved with the image metadata. The key is the string
after `x-image-meta-property-` and the value is the value of the header
Retrieving a Virtual Machine Image
----------------------------------
We want to retrieve that actual raw data for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can issue a `HEAD` request to the Glance
server for the image's URI.
We issue a `GET` request to http://glance.openstack.org/images/1 to
retrieve metadata for that image as well as the image itself encoded
into the response body.
The metadata is returned as a set of HTTP headers that begin with the
prefix `x-image-meta-`. The following shows an example of the HTTP headers
returned from the above `GET` request::
x-image-meta-uri http://glance.openstack.org/images/1
x-image-meta-name Ubuntu 10.04 Plain 5GB
x-image-meta-type kernel
x-image-meta-size 5368709120
x-image-meta-store swift
x-image-meta-created_at 2010-02-03 09:34:01
x-image-meta-updated_at 2010-02-03 09:34:01
x-image-meta-deleted_at
x-image-meta-status available
x-image-meta-is_public True
x-image-meta-property-distro Ubuntu 10.04 LTS
Notes:
* All timestamps returned are in UTC
* The `x-image-meta-updated_at` timestamp is the timestamp when an
image's metadata was last updated, not it's image data, as all
image data is immutable once stored in Glance
* There may be multiple headers that begin with the prefix
`x-image-meta-property-`. These headers are free-form key/value pairs
that have been saved with the image metadata. The key is the string
after `x-image-meta-property-` and the value is the value of the header
* The response's `Content-Length` header shall be equal to the value of
the `x-image-meta-size` header
* The image data itself will be the body of the HTTP response returned
from the request, which will have content-type of
`application/octet-stream`.
Adding a New Virtual Machine Image
----------------------------------
We have created a new virtual machine image in some way (created a
"golden image" or snapshotted/backed up an existing image) and we
wish to do two things:
* Store the disk image data in Glance
* Store metadata about this image in Glance
We can do the above two activities in a single call to the Glance API.
Assuming, like in the examples above, that a Glance API server is running
at `glance.openstack.org`, we issue a `POST` request to add an image to
Glance::
POST http://glance.openstack.org/images/
The metadata about the image is sent to Glance in HTTP headers. The body
of the HTTP request to the Glance API will be the MIME-encoded disk
image data.
Adding Image Metadata in HTTP Headers
*************************************
Glance will view as image metadata any HTTP header that it receives in a
`POST` request where the header key is prefixed with the strings
`x-image-meta-` and `x-image-meta-property-`.
The list of metadata headers that Glance accepts are listed below.
* `x-image-meta-name`
This header is required. Its value should be the name of the image.
Note that the name of an image *is not unique to a Glance node*. It
would be an unrealistic expectation of users to know all the unique
names of all other user's images.
* `x-image-meta-id`
This header is optional.
When present, Glance will use the supplied identifier for the image.
If the identifier already exists in that Glance node, then a
`409 Conflict` will be returned by Glance.
When this header is *not* present, Glance will generate an identifier
for the image and return this identifier in the response (see below)
* `x-image-meta-store`
This header is optional. Valid values are one of `file` or `swift`
When present, Glance will attempt to store the disk image data in the
backing store indicated by the value of the header. If the Glance node
does not support the backing store, Glance will return a `400 Bad Request`.
When not present, Glance will store the disk image data in the backing
store that is marked default. See the configuration option `default_store`
for more information.
* `x-image-meta-type`
This header is required. Valid values are one of `kernel`, `machine`, `raw`,
or `ramdisk`.
* `x-image-meta-size`
This header is optional.
When present, Glance assumes that the expected size of the request body
will be the value of this header. If the length in bytes of the request
body *does not match* the value of this header, Glance will return a
`400 Bad Request`.
When not present, Glance will calculate the image's size based on the size
of the request body.
* `x-image-meta-is_public`
This header is optional.
When present, Glance converts the value of the header to a boolean value,
so "on, 1, true" are all true values. When true, the image is marked as
a public image, meaning that any user may view its metadata and may read
the disk image from Glance.
When not present, the image is assumed to be *not public* and specific to
a user.
* `x-image-meta-property-*`
When Glance receives any HTTP header whose key begins with the string prefix
`x-image-meta-property-`, Glance adds the key and value to a set of custom,
free-form image properties stored with the image. The key is the
lower-cased string following the prefix `x-image-meta-property-` with dashes
and punctuation replaced with underscores.
For example, if the following HTTP header were sent::
x-image-meta-property-distro Ubuntu 10.10
Then a key/value pair of "distro"/"Ubuntu 10.10" will be stored with the
image in Glance.
There is no limit on the number of free-form key/value attributes that can
be attached to the image. However, keep in mind that the 8K limit on the
size of all HTTP headers sent in a request will effectively limit the number
of image properties.

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..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Image Identifiers
=================
Images are uniquely identified by way of a URI that
matches the following signature::
<Glance Server Location>/images/<ID>
where `<Glance Server Location>` is the resource location of the Glance service
that knows about an image, and `<ID>` is the image's identifier that is
*unique to that Glance server*.

591
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@ -1,7 +1,18 @@
.. Glance documentation master file, created by
sphinx-quickstart on Tue May 18 13:50:15 2010.
You can adapt this file completely to your liking, but it should at least
contain the root `toctree` directive.
..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Welcome to Glance's documentation!
==================================
@ -14,555 +25,53 @@ VM images made available through Glance can be stored in a variety of
locations from simple filesystems to object-storage systems like the
OpenStack Swift project.
.. toctree::
:maxdepth: 1
Glance, as with all OpenStack projects, is written with the following design
guidelines in mind:
Overview
* **Component based architecture**: Quickly add new behaviors
* **Highly available**: Scale to very serious workloads
* **Fault tolerant**: Isolated processes avoid cascading failures
* **Recoverable**: Failures should be easy to diagnose, debug, and rectify
* **Open standards**: Be a reference implementation for a community-driven api
This documentation is generated by the Sphinx toolkit and lives in the source
tree. Additional documentation on Glance and other components of OpenStack can
be found on the `OpenStack wiki`_. Also see the :doc:`community` page for
other ways to interact with the community.
.. _`OpenStack wiki`: http://wiki.openstack.org
Concepts
========
The Glance project provides services for discovering, registering, and
retrieving virtual machine images. Glance has a RESTful API that allows
querying of VM image metadata as well as retrieval of the actual image.
.. toctree::
:maxdepth: 1
identifiers
registries
Using Glance
============
.. toctree::
:maxdepth: 1
:maxdepth: 1
The Glance API
glanceapi
client
Developer Docs
==============
Glance has a RESTful API that exposes both metadata about registered virtual
machine images and the image data itself.
A host that runs the `bin/glance-api` service is said to be a *Glance API
Server*.
Assume there is a Glance API server running at the URL
http://glance.openstack.org.
Let's walk through how a user might request information from this server.
Requesting a List of Public VM Images
-------------------------------------
We want to see a list of available virtual machine images that the Glance
server knows about.
We issue a `GET` request to http://glance.openstack.org/images/ to retrieve
this list of available *public* images. The data is returned as a JSON-encoded
mapping in the following format::
{'images': [
{'uri': 'http://glance.openstack.org/images/1',
'name': 'Ubuntu 10.04 Plain',
'type': 'kernel',
'size': '5368709120'}
...]}
Notes:
* All images returned from the above `GET` request are *public* images
Requesting Detailed Metadata on Public VM Images
------------------------------------------------
We want to see more detailed information on available virtual machine images
that the Glance server knows about.
We issue a `GET` request to http://glance.openstack.org/images/detail to
retrieve this list of available *public* images. The data is returned as a
JSON-encoded mapping in the following format::
{'images': [
{'uri': 'http://glance.openstack.org/images/1',
'name': 'Ubuntu 10.04 Plain 5GB',
'type': 'kernel',
'size': '5368709120',
'store': 'swift',
'created_at': '2010-02-03 09:34:01',
'updated_at': '2010-02-03 09:34:01',
'deleted_at': '',
'status': 'available',
'is_public': True,
'properties': {'distro': 'Ubuntu 10.04 LTS'}},
...]}
Notes:
* All images returned from the above `GET` request are *public* images
* All timestamps returned are in UTC
* The `updated_at` timestamp is the timestamp when an image's metadata
was last updated, not it's image data, as all image data is immutable
once stored in Glance
* The `properties` field is a mapping of free-form key/value pairs that
have been saved with the image metadata
Requesting Detailed Metadata on a Specific Image
------------------------------------------------
We want to see detailed information for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can issue a `HEAD` request to the Glance
server for the image's URI.
We issue a `HEAD` request to http://glance.openstack.org/images/1 to
retrieve complete metadata for that image. The metadata is returned as a
set of HTTP headers that begin with the prefix `x-image-meta-`. The
following shows an example of the HTTP headers returned from the above
`HEAD` request::
x-image-meta-uri http://glance.openstack.org/images/1
x-image-meta-name Ubuntu 10.04 Plain 5GB
x-image-meta-type kernel
x-image-meta-size 5368709120
x-image-meta-store swift
x-image-meta-created_at 2010-02-03 09:34:01
x-image-meta-updated_at 2010-02-03 09:34:01
x-image-meta-deleted_at
x-image-meta-status available
x-image-meta-is_public True
x-image-meta-property-distro Ubuntu 10.04 LTS
Notes:
* All timestamps returned are in UTC
* The `x-image-meta-updated_at` timestamp is the timestamp when an
image's metadata was last updated, not it's image data, as all
image data is immutable once stored in Glance
* There may be multiple headers that begin with the prefix
`x-image-meta-property-`. These headers are free-form key/value pairs
that have been saved with the image metadata. The key is the string
after `x-image-meta-property-` and the value is the value of the header
Retrieving a Virtual Machine Image
----------------------------------
We want to retrieve that actual raw data for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can issue a `HEAD` request to the Glance
server for the image's URI.
We issue a `GET` request to http://glance.openstack.org/images/1 to
retrieve metadata for that image as well as the image itself encoded
into the response body.
The metadata is returned as a set of HTTP headers that begin with the
prefix `x-image-meta-`. The following shows an example of the HTTP headers
returned from the above `GET` request::
x-image-meta-uri http://glance.openstack.org/images/1
x-image-meta-name Ubuntu 10.04 Plain 5GB
x-image-meta-type kernel
x-image-meta-size 5368709120
x-image-meta-store swift
x-image-meta-created_at 2010-02-03 09:34:01
x-image-meta-updated_at 2010-02-03 09:34:01
x-image-meta-deleted_at
x-image-meta-status available
x-image-meta-is_public True
x-image-meta-property-distro Ubuntu 10.04 LTS
Notes:
* All timestamps returned are in UTC
* The `x-image-meta-updated_at` timestamp is the timestamp when an
image's metadata was last updated, not it's image data, as all
image data is immutable once stored in Glance
* There may be multiple headers that begin with the prefix
`x-image-meta-property-`. These headers are free-form key/value pairs
that have been saved with the image metadata. The key is the string
after `x-image-meta-property-` and the value is the value of the header
* The response's `Content-Length` header shall be equal to the value of
the `x-image-meta-size` header
* The image data itself will be the body of the HTTP response returned
from the request, which will have content-type of
`application/octet-stream`.
.. toctree::
:maxdepth: 1
:maxdepth: 1
community
Adding a New Virtual Machine Image
----------------------------------
Outstanding Documentation Tasks
===============================
We have created a new virtual machine image in some way (created a
"golden image" or snapshotted/backed up an existing image) and we
wish to do two things:
* Store the disk image data in Glance
* Store metadata about this image in Glance
We can do the above two activities in a single call to the Glance API.
Assuming, like in the examples above, that a Glance API server is running
at `glance.openstack.org`, we issue a `POST` request to add an image to
Glance::
POST http://glance.openstack.org/images/
The metadata about the image is sent to Glance in HTTP headers. The body
of the HTTP request to the Glance API will be the MIME-encoded disk
image data.
Adding Image Metadata in HTTP Headers
*************************************
Glance will view as image metadata any HTTP header that it receives in a
`POST` request where the header key is prefixed with the strings
`x-image-meta-` and `x-image-meta-property-`.
The list of metadata headers that Glance accepts are listed below.
* `x-image-meta-name`
This header is required. Its value should be the name of the image.
Note that the name of an image *is not unique to a Glance node*. It
would be an unrealistic expectation of users to know all the unique
names of all other user's images.
* `x-image-meta-id`
This header is optional.
When present, Glance will use the supplied identifier for the image.
If the identifier already exists in that Glance node, then a
`409 Conflict` will be returned by Glance.
When this header is *not* present, Glance will generate an identifier
for the image and return this identifier in the response (see below)
* `x-image-meta-store`
This header is optional. Valid values are one of `file` or `swift`
When present, Glance will attempt to store the disk image data in the
backing store indicated by the value of the header. If the Glance node
does not support the backing store, Glance will return a `400 Bad Request`.
When not present, Glance will store the disk image data in the backing
store that is marked default. See the configuration option `default_store`
for more information.
* `x-image-meta-type`
This header is required. Valid values are one of `kernel`, `machine`, `raw`,
or `ramdisk`.
* `x-image-meta-size`
This header is optional.
When present, Glance assumes that the expected size of the request body
will be the value of this header. If the length in bytes of the request
body *does not match* the value of this header, Glance will return a
`400 Bad Request`.
When not present, Glance will calculate the image's size based on the size
of the request body.
* `x-image-meta-is_public`
This header is optional.
When present, Glance converts the value of the header to a boolean value,
so "on, 1, true" are all true values. When true, the image is marked as
a public image, meaning that any user may view its metadata and may read
the disk image from Glance.
When not present, the image is assumed to be *not public* and specific to
a user.
* `x-image-meta-property-*`
When Glance receives any HTTP header whose key begins with the string prefix
`x-image-meta-property-`, Glance adds the key and value to a set of custom,
free-form image properties stored with the image. The key is the
lower-cased string following the prefix `x-image-meta-property-` with dashes
and punctuation replaced with underscores.
For example, if the following HTTP header were sent::
x-image-meta-property-distro Ubuntu 10.10
Then a key/value pair of "distro"/"Ubuntu 10.10" will be stored with the
image in Glance.
There is no limit on the number of free-form key/value attributes that can
be attached to the image. However, keep in mind that the 8K limit on the
size of all HTTP headers sent in a request will effectively limit the number
of image properties.
.. toctree::
:maxdepth: 1
Image Identifiers
=================
Images are uniquely identified by way of a URI that
matches the following signature::
<Glance Server Location>/images/<ID>
where `<Glance Server Location>` is the resource location of the Glance service
that knows about an image, and `<ID>` is the image's identifier that is
*unique to that Glance server*.
.. toctree::
:maxdepth: 1
Image Registration
==================
Image metadata made available through Glance can be stored in image
*registries*. Image registries are any web service that adheres to the
Glance RESTful API for image metadata.
.. toctree::
:maxdepth: 1
Using Glance Programmatically with Glance's Client
==================================================
While it is perfectly acceptable to issue HTTP requests directly to Glance
via its RESTful API, sometimes it is better to be able to access and modify
image resources via a client class that removes some of the complexity and
tedium of dealing with raw HTTP requests.
Glance includes a client class for just this purpose. You can retrieve
metadata about an image, change metadata about an image, remove images, and
of course retrieve an image itself via this client class.
Below are some examples of using Glance's Client class. We assume that
there is a Glance server running at the address `glance.openstack.org`
on port `9292`.
Requesting a List of Public VM Images
-------------------------------------
We want to see a list of available virtual machine images that the Glance
server knows about.
Using Glance's Client, we can do this using the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_images()
Requesting Detailed Metadata on Public VM Images
------------------------------------------------
We want to see more detailed information on available virtual machine images
that the Glance server knows about.
Using Glance's Client, we can do this using the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_images_detailed()
Requesting Detailed Metadata on a Specific Image
------------------------------------------------
We want to see detailed information for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get metadata about the
first public image returned, we can use the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
print c.get_image_meta("http://glance.openstack.org/images/1")
Retrieving a Virtual Machine Image
----------------------------------
We want to retrieve that actual raw data for a specific virtual machine image
that the Glance server knows about.
We have queried the Glance server for a list of public images and the
data returned includes the `uri` field for each available image. This
`uri` field value contains the exact location needed to get the metadata
for a specific image.
Continuing the example from above, in order to get both the metadata about the
first public image returned and its image data, we can use the following code::
from glance import client
c = client.Client("glance.openstack.org", 9292)
meta, image_file = c.get_image("http://glance.openstack.org/images/1")
print meta
f = open('some_local_file', 'wb')
for chunk in image_file:
f.write(chunk)
f.close()
Note that the return from Client.get_image() is a tuple of (`metadata`, `file`)
where `metadata` is a mapping of metadata about the image and `file` is a
generator that yields chunks of image data.
.. toctree::
:maxdepth: 1
Adding a New Virtual Machine Image
----------------------------------
We have created a new virtual machine image in some way (created a
"golden image" or snapshotted/backed up an existing image) and we
wish to do two things:
* Store the disk image data in Glance
* Store metadata about this image in Glance
We can do the above two activities in a single call to the Glance client.
Assuming, like in the examples above, that a Glance API server is running
at `glance.openstack.org`, we issue a call to `glance.client.Client.add_image`.
The method signature is as follows::
glance.client.Client.add_image(image_meta, image_data=None)
The `image_meta` argument is a mapping containing various image metadata. The
`image_data` argument is the disk image data.
The list of metadata that `image_meta` can contain are listed below.
* `name`
This key/value is required. Its value should be the name of the image.
Note that the name of an image *is not unique to a Glance node*. It
would be an unrealistic expectation of users to know all the unique
names of all other user's images.
* `id`
This key/value is optional.
When present, Glance will use the supplied identifier for the image.
If the identifier already exists in that Glance node, then a
`glance.common.exception.Duplicate` will be raised.
When this key/value is *not* present, Glance will generate an identifier
for the image and return this identifier in the response (see below)
* `store`
This key/value is optional. Valid values are one of `file` or `swift`
When present, Glance will attempt to store the disk image data in the
backing store indicated by the value. If the Glance node does not support
the backing store, Glance will raise a `glance.common.exception.BadRequest`
When not present, Glance will store the disk image data in the backing
store that is marked default. See the configuration option `default_store`
for more information.
* `type`
This key/values is required. Valid values are one of `kernel`, `machine`,
`raw`, or `ramdisk`.
* `size`
This key/value is optional.
When present, Glance assumes that the expected size of the request body
will be the value. If the length in bytes of the request body *does not
match* the value, Glance will raise a `glance.common.exception.BadRequest`
When not present, Glance will calculate the image's size based on the size
of the request body.
* `is_public`
This key/value is optional.
When present, Glance converts the value to a boolean value, so "on, 1, true"
are all true values. When true, the image is marked as a public image,
meaning that any user may view its metadata and may read the disk image from
Glance.
When not present, the image is assumed to be *not public* and specific to
a user.
* `properties`
This key/value is optional.
When present, the value is assumed to be a mapping of free-form key/value
attributes to store with the image.
For example, if the following is the value of the `properties` key in the
`image_meta` argument::
{'distro': 'Ubuntu 10.10'}
Then a key/value pair of "distro"/"Ubuntu 10.10" will be stored with the
image in Glance.
There is no limit on the number of free-form key/value attributes that can
be attached to the image with `properties`. However, keep in mind that there
is a 8K limit on the size of all HTTP headers sent in a request and this
number will effectively limit the number of image properties.
As a complete example, the following code would add a new machine image to
Glance::
from glance.client import Client
c = Client("glance.openstack.org", 9292)
meta = {'name': 'Ubuntu 10.10 5G',
'type': 'machine',
'is_public': True,
'properties': {'distro': 'Ubuntu 10.10'}}
new_meta = c.add_image(meta, open('/path/to/image.tar.gz'))
print 'Stored image. Got identifier: %s' % new_meta['id']
.. toctree::
:maxdepth: 1
.. todolist::
Indices and tables
==================

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..
Copyright 2010 OpenStack, LLC
All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Image Registries
================
Image metadata made available through Glance can be stored in image
*registries*. Image registries are any web service that adheres to the
Glance RESTful API for image metadata.