This post shows the details of enabling S3 API for Swift Object Storage on Openstack Kilo on CentOS 7.
The main documentation is here: http://docs.openstack.org/kilo/config-reference/content/configuring-openstack-object-storage-with-s3_api.html
As of July 2015, the page seems dated as some links are broken and steps are config options are unclear.

Install Swift3 Middleware

The Swift3 middleware seems to have shifted to https://github.com/stackforge/swift3

So the correct git clone command is

git clone https://github.com/stackforge/swift3.git

python setup.py install

At the end of the above command’s execution, you should see:

Copying swift3.egg-info to /usr/lib/python2.7/site-packages/swift3-1.8.0.dev8-py2.7.egg-info
running install_scripts

Adjust proxy-server.conf

For Keystone, add “swift3 ” and “s3token” to pipeline.

For others, add swauth instead of s3token (untested).

[pipeline:main]

pipeline = catch_errors healthcheck cache swift3 s3token authtoken keystoneauth ...

[filter:swift3]
use = egg:swift3#swift3
 
[filter:s3token]
paste.filter_factory = keystonemiddleware.s3_token:filter_factory
auth_port = 35357 
auth_host = keystone_ip_address 
auth_protocol = http

The important part is the filter_factory its —  keystonemiddleware and not keystone.middleware. Then restart the swift proxy service.

sudo service openstack-swift-proxy restart

Testing the Swift S3 API using S3Curl

S3Curl is a tool provided by Amazon. It can be downloaded from https://aws.amazon.com/code/128. Also note the comment in that page where you need to yum install perl-Digest-HMAC package.
You can use Horizon to create a test container and upload a small text file into it.
In our example, we have created a container called “test_container” and simple text file called “test_obj” inside the container.

Make sure you edit the s3curl.pl file to use Openstack’s Swift Proxy end point:

my @endpoints = ( '172.0.0.8');

Retrieve the access keys from Horizon dashboard

Go to Project -> Compute -> Access & Security. Click on the API Access tab.
Note the S3 Service endpoint. In our case: http://172.0.0.8:8080

On the top right click on view credentials:
on Horizon
“EC2 Access Key” –> Is your id for S3 tools such as S3Curl.
“EC2 Secret Key” –> Is your key for S3 tools such as S3Curl.

For instance, lets say:
EC2 Access Key = HorizonEC2AccessKeyA0919319
EC2 Secret Key = HorizonEC2SecretKeyS1121551

Get the list of containers

The S3Curl command is:
./s3curl.pl --id HorizonEC2AccessKeyA0919319 --key HorizonEC2SecretKeyS1121551 http://172.0.0.8:8080

Note: The above ID is the actual key not the personal .s3curl file reference. The tool will give a few warnings, but that ok we are just testing.

Expected output is:

 <?xml version='1.0' encoding='UTF-8'?>
<ListAllMyBucketsResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/"><Owner><ID>admin:admin</ID><DisplayName>admin:admin</DisplayName></Owner><Buckets><Bucket><Name>test_container</Name><CreationDate>2009-02-03T16:45:09.000Z</CreationDate></Bucket></Buckets></ListAllMyBucketsResult>

The above indicates the root of our storage contains a bucket by name test_container. Lets extract the files from that container (bucket).

Get the list of objects in the container

To get the list of object inside the container, execute:

./s3curl.pl --id HorizonEC2AccessKeyA0919319 --key HorizonEC2SecretKeyS1121551 http://172.0.0.8:8080/test_container

The output will have something like:

. . . <Contents><Key>test_obj</Key><LastModified>. . .

In above, key is the file. If you simply want to stream the contents of test_obj:

./s3curl.pl --id HorizonEC2AccessKeyA0919319 --key HorizonEC2SecretKeyS1121551 http://172.0.0.8:8080/test_container/test_obj

You should see test_obj’s contents printed out.

This concludes that our setup is working fine.