x
/
downpour
Code Issues Proposed changes

add documentation 

Change-Id: I37a11f198d020067283ca5c154e610f2ff6770c1
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
This commit is contained in:
Doug Hellmann 2017-05-01 12:12:30 -04:00
parent ce5d35840c
commit 34454593ff
12 changed files with 314 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
README.rst
View File

@ -1,6 +1,6 @@
==================================================
downpour -- OpenStack Tenant Data Migration Tool
==================================================
===================================================
downpour --- OpenStack Tenant Data Migration Tool
===================================================
downpour exports tenant data from an OpenStack cloud to create a set
of Ansible playbooks for importing the data into another cloud.

3
demo/tiny-resources.yml
View File

@ -1,7 +1,8 @@
# Resource file for downpour using the instance created in tiny.yml.
servers:
- name: downpour-demo-tiny
# Create the server using a separate key than it was created with in tiny.yml.
# Create the server using a separate key than
# it was created with in tiny.yml.
key_name: downpour-demo2
keypairs:
- name: downpour-demo

57
doc/source/background.rst Normal file
View File

@ -0,0 +1,57 @@
============
Background
============
Downpour is being created to solve the problem of moving workloads
between clouds. It is only one of several possible approaches to the
problem, and fits into a very specific niche at the hard end of the
range of use cases.
.. list-table::
:header-rows: 1
- *
* Easy
* Moderate
* Hard
- * **Ownership**
* Operator
* Admin
* Tenant
- * **Backend**
* Shared storage
* Fast interconnect
* Shared nothing
- * **Applications**
* One per tenant
* Multi-app with naming conventions
* Rats nest
Downpour does not assume the user has an special access to the cloud,
either as an operator with access to backend systems or via admin
APIs.
Downpour does not assume that the source and destination clouds are
connected in any way. Not only is it possible to move data between
clouds that do not share backend services, it is possible to move data
between clouds that cannot be accessed from the same system at the
same time.
Downpour does not make any assumptions about the mapping between
applications and tenants. It is possible to extract only part of the
resources owned by a tenant. The grouping is completely up to the
user, and can represent an application or a single node in a multi-VM
configuration.
Downpour does not assume the source and destination clouds are build
using the same architecture or configured in the same way. As long as
the two clouds pass the standard OpenStack interoperability tests, it
should be possible to use Downpour to move your workload.
These requirements do come with trade-offs, the impact of which will
depend on how "cloud native" an application really is. For example,
the benefits of copy-on-write images may be lost during the migration
if the entire image from each VM needs to be uploaded into the new
cloud. The UUIDs associated with resources will also change, since
there is no way to guarantee the assignment of a specific UUID for
resources created in a separate cloud.

4
doc/source/conf.py
View File

@ -23,7 +23,6 @@ sys.path.insert(0, os.path.abspath('../..'))
extensions = [
'sphinx.ext.autodoc',
#'sphinx.ext.intersphinx',
'oslosphinx'
]
# autodoc generation is a bit aggressive and a nuisance when doing heavy
@ -38,7 +37,7 @@ master_doc = 'index'
# General information about the project.
project = u'downpour'
copyright = u'2016, OpenStack Foundation'
copyright = u'2017, Downpour contributors'
# If true, '()' will be appended to :func: etc. cross-reference text.
add_function_parentheses = True
@ -57,6 +56,7 @@ pygments_style = 'sphinx'
# html_theme_path = ["."]
# html_theme = '_theme'
# html_static_path = ['static']
html_theme = 'nature'
# Output file base name for HTML help builder.
htmlhelp_basename = '%sdoc' % project

7
doc/source/contributing.rst
View File

@ -1,4 +1,5 @@
============
Contributing
============
==============
Contributing
==============
.. include:: ../../CONTRIBUTING.rst

10
doc/source/glossary.rst Normal file
View File

@ -0,0 +1,10 @@
==========
Glossary
==========
.. glossary::
resource file
A YAML file containing explicitly identified resources to be
exported. See :doc:`resource_file` for more details.

32
doc/source/index.rst
View File

@ -1,25 +1,25 @@
.. downpour documentation master file, created by
sphinx-quickstart on Tue Jul 9 22:26:36 2013.
You can adapt this file completely to your liking, but it should at least
contain the root `toctree` directive.
==================================================
downpour -- OpenStack Tenant Data Migration Tool
==================================================
Welcome to downpour's documentation!
========================================================
downpour exports tenant data from an OpenStack cloud to create a set
of Ansible_ playbooks for importing the data into another cloud.
Contents:
.. note::
The project is in a very very early prototyping stage.
.. _ansible: https://www.ansible.com
Contents
========
.. toctree::
:maxdepth: 2
readme
background
installation
usage
resource_file
contributing
Indices and tables
==================
* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`
glossary

29
doc/source/installation.rst
View File

@ -1,12 +1,27 @@
============
Installation
============
==============
Installation
==============
Prerequisites
=============
Downpour is written to take advantage of features of Python 3.5, so
you will need a Python 3.5+ interpreter installed.
Installing with pip
===================
At the command line::
$ pip install downpour
$ pip install os-downpour
Or, if you have virtualenvwrapper installed::
.. note:: The dist name for downpour is ``os-downpour``.
$ mkvirtualenv downpour
$ pip install downpour
Cloud Access Credentials
========================
downpour uses `os-client-config`_ for settings related to accessing
the cloud. Fill in your ``clouds.yaml`` or use the environment
variables or command line arguments provided.
.. _os-client-config: http://docs.openstack.org/developer/os-client-config/

1
doc/source/readme.rst
View File

@ -1 +0,0 @@
.. include:: ../../README.rst

83
doc/source/resource_file.rst Normal file
View File

@ -0,0 +1,83 @@
======================
Resource File Format
======================
A Downpour resource file is a YAML file containing explicitly
identified resources to be exported, along with instructions for how
to handle the export.
``keypairs``
============
The keypairs section lists the names of the keypairs to be
exported. Keys associated with servers are exported automatically, but
if it is important to move keys not in use by any of the servers those
keys can be listed separately.
Each item in the keypairs list should be a mapping with a value for
``name``.
::
keypairs:
- name: downpour-demo
``images``
==========
The images section lists the names of the images to be exported.
Each item in the images list should be a mapping with a value for
``name``.
::
images:
- name: cirros-0.3.5-x86_64-disk
``volumes``
===========
The volumes section lists the names and settings for the unattached
volumes to be exported. This section should **not** include volumes
attached to servers, because those are exported as part of exporting
the server definition.
Each item in the images list should be a mapping with a value for
``name`` and an optional boolean value for ``save_state``, indicating
whether the contents of the volume should be exported. If
``save_state`` is false, a new volume with the same name and size will
be created but it will be empty. The default is to save the contents
of the volume.
::
volumes:
- name: downpour-demo-unattached
save_state: false
``servers``
===========
The servers section lists the names and settings for the virtual
machines to be exported.
Each item in the images list should be a mapping with a value for
``name``. It can also contain an optional boolean value for
``save_state``, indicating whether the contents of the VM should be
exported. If ``save_state`` is false, a new VM with the same name and
flavor will be created, but it will not contain any of the files from
the current VM. The default is to save the contents of the volume.
If an optional ``key_name`` setting is given, the new VM will be
initialized using that ssh keypair instead of the one already
associated with the server. The keypair does not need to exist on the
source system.
::
servers:
- name: downpour-demo-tiny
# Create the server using a separate key than
# it was created with in tiny.yml.
key_name: downpour-demo2

119
doc/source/usage.rst
View File

@ -1,7 +1,116 @@
========
Usage
========
=======
Usage
=======
To use downpour in a project::
Downpour uses a four step process. Between each step it is possible to
stop and modify the data that has been prepared to pass to the next
step.
import downpour
1. Identify Resources to Export
===============================
The first phase of using Downpour is to identify exactly what
resources will be exported from the cloud to build the :term:`resource
file`. This step can be performed by hand by creating the required
input file in a text editor, or the file can be build using the
``query`` command.
The resource file is a YAML file with sections for the principle
resource types, ``keypairs``, ``images``, ``volumes``, and
``servers``. Resources are identified by name, and may also include
extra parameters to control how the export and re-import operations
are performed. For example, this resource file causes the
``downpour-demo-tiny`` server to be exported but when it is recreated
a different ssh key is used to provide access to log in.
.. literalinclude:: ../../demo/tiny-resources.yml
The ``downpour query`` command also can be used to find resources
visible in the cloud, and add them to the resource file. It supports
wildcard patterns in names and other criteria for filtering
resources. For example, this command finds all servers with "``tiny``"
in their name.
::
$ downpour query --server-name '*tiny*' export.yml
.. seealso::
:doc:`resource_file` includes more details about resource files.
2. Exporting Resources
======================
The second phase of operation is to actually export the resources from
the cloud using ``downpour export``, passing the resource file as
input. Downpour starts by processing the resources listed in the file
explicitly, and identifies any extra dependencies needed to recreate
the configuration of those resources. For example, the networks,
subnets, and security groups used by a server are exported
automatically, as are the volumes attached to the server.
::
$ downpour export export.yml ./export/
The output for the export process is an Ansible_ playbook to recreate
the resources, with all relationships intact. For images, volumes, and
servers with the ``save-state`` flag set to true, the content of the
resource will be downloaded and saved to the output directory where it
can be used to recreate the resource.
3. Importing Resources
======================
The import phase uses ``ansible-playbook`` to run the playbook created
by the exporter.
.. note::
Although Downpour currently requires Python 3.5 or greater, Ansible
is a Python 2.x application. If you are using ``pip`` and
``virtualenv`` to install the tools, you will need to install them
in separate virtual environments.
Ansible uses uses `os-client-config`_ for settings related to
accessing the cloud. The simplest way to configure the cloud is via a
``clouds.yaml`` file, but any mechanism supported by Ansible will
work. The credentials used for the import phase do not need to be the
same as the export phase. In fact, they're likely to be completely
different because they will refer to a separate cloud's API endpoints.
Downpour supports some customizations during export, such as changing
the ssh key to be used for accessing a server. Other changes can be
made by editing the playbook before running it.
The playbook produced by Downpour creates each resource, then adds a
line to a file ``uuids.csv`` to map the UUID in the source cloud to
the UUID in the target cloud. This file may be useful for updating
scripts or other configuration that rely on the UUID instead of a
unique name for the resource.
::
"Resource Type","Resource Name","Old","New"
"security group","downpour-demo","6deea469-54bd-4846-b12a-79fa6b482280","a4b80ffc-bc51-485c-915a-9ba9a7b4dcf0"
"volume","downpour-demo-tiny","256868c6-441f-4cd3-96fd-bda92c33822c","62e5616c-9a8c-44e2-bd14-4685b905ea94"
"security group","downpour-demo","3c7dcb77-d9ac-4af1-ba95-3f5d89a85227","a4b80ffc-bc51-485c-915a-9ba9a7b4dcf0"
"volume","downpour-demo-tiny","a6192546-c36e-4bee-ad00-8229e0b0efc5","62e5616c-9a8c-44e2-bd14-4685b905ea94"
"network","private","56a86bdb-13b2-4c9f-b8f5-a942d52602b5","f3027502-e4a2-4610-81fb-c6df99ead5c3"
"subnet","ipv6-private-subnet","8d736fe4-6b8f-4bf5-a38e-b511dce21f7f","01025e33-703b-4aa4-b6ec-80036bb3679b"
"subnet","private-subnet","e6baf9f4-09b5-4292-8236-3cca609ec2a3","2f9a1686-8125-4316-acd3-dbee51c44c1d"
"keypair","downpour-demo","downpour-demo","downpour-demo"
"image","cirros-0.3.5-x86_64-disk","570ec7bd-011b-4fbe-9968-626225654a7f","570ec7bd-011b-4fbe-9968-626225654a7f"
.. _ansible: https://www.ansible.com
.. _os-client-config: http://docs.openstack.org/developer/os-client-config/
4. Decomissioning Resources
===========================
Downpour is not a live-migration tool, and it does not delete any
resources from the source cloud. This allows you to perform
application-specific migration (such as a final database sync) before
updating any load balancers or DNS records and deleting old
information.

1
setup.cfg
View File

@ -28,6 +28,7 @@ console_scripts =
source-dir = doc/source
build-dir = doc/build
all_files = 1
warning-is-error = 1
[upload_sphinx]
upload-dir = doc/build/html