openstack/swift
Code Issues Proposed changes
9cafa472a3
swift/doc/source/cors.rst
Atsushi SAKAI 964869accc Fix six typos on swift documentation 
mechanisim => mechanism
    http://docs.openstack.org/developer/swift/cors.html
overridde => override
   http://docs.openstack.org/developer/swift/deployment_guide.html
extentsions => extensions
  http://docs.openstack.org/developer/swift/development_ondisk_backends.html
reuqest => request
  http://docs.openstack.org/developer/swift/logs.html
suport => support
  http://docs.openstack.org/developer/swift/overview_architecture.html
mininum => minimum
  http://docs.openstack.org/developer/swift/overview_erasure_code.html

$ git diff | diffstat
 cors.rst | 2 +-
 deployment_guide.rst | 2 +-
 development_ondisk_backends.rst | 2 +-
 logs.rst | 2 +-
 overview_architecture.rst | 2 +-
 overview_erasure_code.rst | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

Change-Id: I8e095f4c216b2cfae48dff1e17d387048349f73c
Closes-Bug: #1477877
2015-07-24 17:11:49 +09:00

3.9 KiB
Raw Blame History

CORS

CORS is a mechanism to allow code running in a browser (Javascript for example) make requests to a domain other then the one from where it originated.

Swift supports CORS requests to containers and objects.

CORS metadata is held on the container only. The values given apply to the container itself and all objects within it.

The supported headers are,

Metadata Use
X-Container-Meta-Access-Control-Allow-Origin Origins to be allowed to make Cross Origin Requests, space separated.
X-Container-Meta-Access-Control-Max-Age Max age for the Origin to hold the preflight results.
X-Container-Meta-Access-Control-Expose-Headers Headers exposed to the user agent (e.g. browser) in the the actual request response. Space separated.

Before a browser issues an actual request it may issue a preflight request. The preflight request is an OPTIONS call to verify the Origin is allowed to make the request. The sequence of events are,

  • Browser makes OPTIONS request to Swift
  • Swift returns 200/401 to browser based on allowed origins
  • If 200, browser makes the "actual request" to Swift, i.e. PUT, POST, DELETE, HEAD, GET

When a browser receives a response to an actual request it only exposes those headers listed in the Access-Control-Expose-Headers header. By default Swift returns the following values for this header,

  • "simple response headers" as listed on http://www.w3.org/TR/cors/#simple-response-header
  • the headers etag, x-timestamp, x-trans-id
  • all metadata headers (X-Container-Meta-* for containers and X-Object-Meta-* for objects)
  • headers listed in X-Container-Meta-Access-Control-Expose-Headers

Sample Javascript

To see some CORS Javascript in action download the test CORS page (source below). Host it on a webserver and take note of the protocol and hostname (origin) you'll be using to request the page, e.g. http://localhost.

Locate a container you'd like to query. Needless to say the Swift cluster hosting this container should have CORS support. Append the origin of the test page to the container's X-Container-Meta-Access-Control-Allow-Origin header,:

curl -X POST -H 'X-Auth-Token: xxx' \
  -H 'X-Container-Meta-Access-Control-Allow-Origin: http://localhost' \
  http://192.168.56.3:8080/v1/AUTH_test/cont1

At this point the container is now accessible to CORS clients hosted on http://localhost. Open the test CORS page in your browser.

  1. Populate the Token field
  2. Populate the URL field with the URL of either a container or object
  3. Select the request method
  4. Hit Submit

Assuming the request succeeds you should see the response header and body. If something went wrong the response status will be 0.

Test CORS Page

A sample cross-site test page is located in the project source tree doc/source/test-cors.html.

test-cors.html