b0c8de699e
Shard containers learn about their own shard range by fetching shard ranges from the root container during the sharder audit phase. Since [1], if the shard is shrinking, it may also learn about acceptor shards in the shard ranges fetched from the root. However, the fetched shard ranges do not currently include the root's own shard range, even when the root is to be the acceptor for a shrinking shard. This prevents the mechanism being used to perform shrinking to root. This patch modifies the root container behaviour to include its own shard range in responses to shard containers when the container GET request param 'states' has value 'auditing'. This parameter is used to indicate that a particular GET request is from the sharder during shard audit; the root does not otherwise include its own shard range in GET responses. When the 'states=auditing' parameter is used with a container GET request the response includes all shard ranges except those in the FOUND state. The shard ranges of relevance to a shard are its own shard range and any overlapping shard ranges that may be acceptors if the shard is shrinking. None of these relevant shard ranges should be in state FOUND: the shard itself cannot be in FOUND state since it has been created; acceptor ranges should not be in FOUND state. The FOUND state is therefore excluded from the 'auditing' states to prevent an unintended overlapping FOUND shard range that has not yet been resolved at the root container being fetched by a shrinking shard, which might then proceed to create and cleave to it. The shard only merges the root's shard range (and any other shard ranges) when the shard is shrinking. If the root shard range is ACTIVE then it is the acceptor and will be used when the shard cleaves. If the root shard range is in any other state then it will be ignored when the shard cleaves to other acceptors. The sharder cleave loop is modified to break as soon as cleaving is done i.e. cleaving has been completed up to the shard's upper bound. This prevents misleading logging that cleaving has stopped when in fact cleaving to a non-root acceptor has completed but the shard range list still contains an irrelevant root shard range in SHARDED state. This also prevents cleaving to more than one acceptor in the unexpected case that multiple active acceptors overlap the shrinking shard - cleaving will now complete once the first acceptor has cleaved. [1] Related-Change: I9034a5715406b310c7282f1bec9625fe7acd57b6 Change-Id: I5d48b67217f705ac30bb427ef8d969a90eaad2e5
OpenStack Swift
OpenStack Swift is 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 https://docs.openstack.org/swift/latest/.
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 run:
pip install -r requirements.txt -r doc/requirements.txt
sphinx-build -W -b html doc/source doc/build/htmland then browse to doc/build/html/index.html. These docs are auto-generated after every commit and available online at https://docs.openstack.org/swift/latest/.
For Developers
Getting Started
Swift is part of OpenStack and follows the code contribution, review, and testing processes common to all OpenStack projects.
If you would like to start contributing, check out these notes to help you get started.
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.
Tests
There are three types of tests included in Swift's source tree.
- Unit tests
- Functional tests
- Probe tests
Unit tests check that small sections of the code behave properly. For example, a unit test may test a single function to ensure that various input gives the expected output. This validates that the code is correct and regressions are not introduced.
Functional tests check that the client API is working as expected. These can be run against any endpoint claiming to support the Swift API (although some tests require multiple accounts with different privilege levels). These are "black box" tests that ensure that client apps written against Swift will continue to work.
Probe tests are "white box" tests that validate the internal workings of a Swift cluster. They are written to work against the "SAIO - Swift All In One" dev environment. For example, a probe test may create an object, delete one replica, and ensure that the background consistency processes find and correct the error.
You can run unit tests with .unittests, functional tests
with .functests, and probe tests with
.probetests. There is an additional .alltests
script that wraps the other three.
To fully run the tests, the target environment must use a filesystem
that supports large xattrs. XFS is strongly recommended. For unit tests
and in-process functional tests, either mount /tmp with XFS
or provide another XFS filesystem via the TMPDIR
environment variable. Without this setting, tests should still pass, but
a very large number will be skipped.
Code Organization
- bin/: Executable scripts that are the processes run by the deployer
- doc/: Documentation
- etc/: Sample config files
- examples/: Config snippets used in the docs
- swift/: Core code
- account/: account server
- cli/: code that backs some of the CLI tools in bin/
- common/: code shared by different modules
- middleware/: "standard", officially-supported middleware
- ring/: code implementing Swift's ring
- container/: container server
- locale/: internationalization (translation) data
- obj/: object server
- proxy/: proxy server
- test/: Unit, functional, and probe 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 https://docs.openstack.org/swift/latest/. A good starting point is at https://docs.openstack.org/swift/latest/deployment_guide.html There is an ops runbook that gives information about how to diagnose and troubleshoot common issues when running a Swift cluster.
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 https://github.com/openstack/python-swiftclient.
Complete API documentation at https://docs.openstack.org/api-ref/object-store/
There is a large ecosystem of applications and libraries that support and work with OpenStack Swift. Several are listed on the associated projects page.
For more information come hang out in #openstack-swift on freenode.
Thanks,
The Swift Development Team