8825c9c74a
Enhance internally logged messages to report referer and user-agent.
Pass the referering URL and METHOD between internal servers (when
known), and set the user-agent to be the server type (obj-server,
container-server, proxy-server, obj-updater, obj-replicator,
container-updater, direct-client, etc.) with the process PID. In
conjunction with the transaction ID, it helps to track down which PID
from a given system was responsible for initiating the request and
what that server was working on to make this request.
This has been helpful in tracking down interactions between object,
container and account servers.
We also take things a bit further performaing a bit of refactoring to
consolidate calls to transfer_headers() now that we have a helper
method for constructing them.
Finally we performed further changes to avoid header key duplication
due to string literal header key values and the various objects
representing headers for requests and responses. See below for more
details.
====
Header Keys
There seems to be a bit of a problem with the case of the various
string literals used for header keys and the interchangable way
standard Python dictionaries, HeaderKeyDict() and HeaderEnvironProxy()
objects are used.
If one is not careful, a header object of some sort (one that does not
normalize its keys, and that is not necessarily a dictionary) can be
constructed containing header keys which differ only by the case of
their string literals. E.g.:
{ 'x-trans-id': '1234', 'X-Trans-Id': '5678' }
Such an object, when passed to http_connect() will result in an
on-the-wire header where the key values are merged together, comma
separated, that looks something like:
HTTP_X_TRANS_ID: 1234,5678
For some headers in some contexts, this is behavior is desirable. For
example, one can also use a list of tuples which enumerate the multiple
values a single header should have.
However, in almost all of the contexts used in the code base, this is
not desirable.
This behavior arises from a combination of factors:
1. Header strings are not constants and different lower-case and
title-case header strings values are used interchangably in the
code at times
It might be worth the effort to make a pass through the code to
stop using string literals and use constants instead, but there
are plusses and minuses to doing that, so this was not attempted
in this effort
2. HeaderEnvironProxy() objects report their keys in ".title()"
case, but normalize all other key references to the form
expected by the Request class's environ field
swob.Request.headers fields are HeaderEnvironProxy() objects.
3. HeaderKeyDict() objects report their keys in ".lower()" case,
and normalize all other key references to ".lower()" case
swob.Response.headers fields are HeaderKeyDict() objects.
Depending on which object is used and how it is used, one can end up
with such a mismatch.
This commit takes the following steps as a (PROPOSED) solution:
1. Change HeaderKeyDict() to normalize using ".title()" case to
match HeaderEnvironProxy()
2. Replace standard python dictionary objects with HeaderKeyDict()
objects where possible
This gives us an object that normalizes key references to avoid
fixing the code to normalize the string literals.
3. Fix up a few places to use title case string literals to match
the new defaults
Change-Id: Ied56a1df83ffac793ee85e796424d7d20f18f469
Signed-off-by: Peter Portante <peter.portante@redhat.com>
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://doc.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