OpenStack Storage (Swift)
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Samuel Merritt 1901719542 Move all SLO functionality to middleware
This way, with zero additional effort, SLO will support enhancements
to object storage and retrieval, such as:
 * automatic resume of GETs on broken connection (today)
 * storage policies (in the near future)
 * erasure-coded object segments (in the far future)

This also lets SLOs work with other sorts of hypothetical third-party
middleware, for example object compression or encryption.

Getting COPY to work here is sort of a hack; the proxy's object
controller now checks for "swift.copy_response_hook" in the request's
environment and feeds the GET response (the source of the new object's
data) through it. This lets a COPY of a SLO manifest actually combine
the segments instead of merely copying the manifest document.

Updated ObjectController to expect a response's app_iter to be an
iterable, not just an iterator. (PEP 333 says "When called by the
server, the application object must return an iterable yielding zero
or more strings." ObjectController was just being too strict.) This
way, SLO can re-use the same response-generation logic for GET and
COPY requests.

Added a (sort of hokey) mechanism to allow middlewares to close
incompletely-consumed app iterators without triggering a warning. SLO
does this when it realizes it's performed a ranged GET on a manifest;
it closes the iterable, removes the range, and retries the
request. Without this change, the proxy logs would get 'Client
disconnected on read' in them.

DocImpact

blueprint multi-ring-large-objects

Change-Id: Ic11662eb5c7176fbf422a6fc87a569928d6f85a1
2014-01-13 10:52:29 -08:00
bin Merge "Remove swiftclient dep on direct_client" 2014-01-07 21:24:27 +00:00
doc Add Swift-account-stats as a related project. 2014-01-08 10:06:22 +01:00
etc Move all SLO functionality to middleware 2014-01-13 10:52:29 -08:00
examples Add a user variable to templates 2013-09-17 11:46:04 +10:00
locale Reverted the pulling out of various middleware: 2012-05-16 21:25:10 +00:00
swift Move all SLO functionality to middleware 2014-01-13 10:52:29 -08:00
test Move all SLO functionality to middleware 2014-01-13 10:52:29 -08:00
.coveragerc Align tox.ini and fix coverage jobs in jenkins. 2012-06-08 20:05:14 -04:00
.functests Move the tests from functionalnosetests 2014-01-07 15:58:11 +08:00
.gitignore fix(gitignore) : ignore *.egg and *.egg-info 2013-07-30 15:11:00 -04:00
.gitreview Add .gitreview config file for gerrit. 2011-10-24 15:05:49 -04:00
.mailmap Release notes for Swift 1.11.0 2013-12-06 09:21:50 -08:00
.probetests Allow specify arguments to .probetests script 2013-12-24 01:18:19 -08:00
.unittests make test tooling less opinionated 2013-12-06 12:07:52 -08:00
AUTHORS Release notes for Swift 1.11.0 2013-12-06 09:21:50 -08:00
babel.cfg add pybabel setup.py commands and initial .pot 2011-01-27 00:01:24 +00:00
CHANGELOG clarify the current state of the DiskFile API 2013-12-09 10:33:53 -08:00
CONTRIBUTING.md HEAD on account returns 410 if account was deleted and not yet reaped 2013-10-29 13:49:38 -07:00
LICENSE Convert LICENSE to use unix style line endings. 2012-12-19 12:48:27 -05:00
MANIFEST.in Add requirements files to the source distribution 2013-06-03 19:26:20 +04:00
README.md Correct URL in readme 2013-10-07 22:27:34 -07:00
requirements.txt Make pbr a build-time only dependency 2013-10-29 12:29:49 -07:00
setup.cfg Generic means for persisting system metadata. 2014-01-06 22:29:37 +00:00
setup.py Migrate to pbr for build 2013-08-14 19:10:07 -03:00
test-requirements.txt Sync global requirements to pin sphinx to sphinx>=1.1.2,<1.2 2013-12-10 17:31:21 -05:00
tox.ini Whitelist external netifaces requirement 2014-01-06 03:38:47 +00:00

Swift

A distributed object storage system designed to scale from a single machine to thousands of servers. Swift is optimized for multi-tenancy and high concurrency. Swift is ideal for backups, web and mobile content, and any other unstructured data that can grow without bound.

Swift provides a simple, REST-based API fully documented at http://docs.openstack.org/.

Swift was originally developed as the basis for Rackspace's Cloud Files and was open-sourced in 2010 as part of the OpenStack project. It has since grown to include contributions from many companies and has spawned a thriving ecosystem of 3rd party tools. Swift's contributors are listed in the AUTHORS file.

Docs

To build documentation install sphinx (pip install sphinx), run python setup.py build_sphinx, and then browse to /doc/build/html/index.html. These docs are auto-generated after every commit and available online at http://docs.openstack.org/developer/swift/.

For Developers

The best place to get started is the "SAIO - Swift All In One". This document will walk you through setting up a development cluster of Swift in a VM. The SAIO environment is ideal for running small-scale tests against swift and trying out new features and bug fixes.

You can run unit tests with .unittests and functional tests with .functests.

Code Organization

  • bin/: Executable scripts that are the processes run by the deployer
  • doc/: Documentation
  • etc/: Sample config files
  • swift/: Core code
    • account/: account server
    • common/: code shared by different modules
      • middleware/: "standard", officially-supported middleware
      • ring/: code implementing Swift's ring
    • container/: container server
    • obj/: object server
    • proxy/: proxy server
  • test/: Unit and functional tests

Data Flow

Swift is a WSGI application and uses eventlet's WSGI server. After the processes are running, the entry point for new requests is the Application class in swift/proxy/server.py. From there, a controller is chosen, and the request is processed. The proxy may choose to forward the request to a back- end server. For example, the entry point for requests to the object server is the ObjectController class in swift/obj/server.py.

For Deployers

Deployer docs are also available at http://docs.openstack.org/developer/swift/. A good starting point is at http://docs.openstack.org/developer/swift/deployment_guide.html

You can run functional tests against a swift cluster with .functests. These functional tests require /etc/swift/test.conf to run. A sample config file can be found in this source tree in test/sample.conf.

For Client Apps

For client applications, official Python language bindings are provided at http://github.com/openstack/python-swiftclient.

Complete API documentation at http://docs.openstack.org/api/openstack-object-storage/1.0/content/


For more information come hang out in #openstack-swift on freenode.

Thanks,

The Swift Development Team