swift 2.24.0

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.

1. Unit tests

2. Functional tests

3. 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.