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+=========
+STS Lite
+=========
+
+Ceph Object Gateway provides support for a subset of Amazon Secure Token Service
+(STS) APIs. STS Lite is an extension of STS and builds upon one of its APIs to
+decrease the load on external IDPs like Keystone and LDAP.
+
+A set of temporary security credentials is returned after authenticating
+a set of AWS credentials with the external IDP. These temporary credentials can be used
+to make subsequent S3 calls which will be authenticated by the STS engine in Ceph,
+resulting in less load on the Keystone/ LDAP server.
+
+Temporary and limited privileged credentials can be obtained for a local user
+also using the STS Lite API.
+
+STS Lite REST APIs
+==================
+
+The following STS Lite REST API is part of STS Lite in Ceph Object Gateway:
+
+1. GetSessionToken: Returns a set of temporary credentials for a set of AWS
+credentials. After initial authentication with Keystone/ LDAP, the temporary
+credentials returned can be used to make subsequent S3 calls. The temporary
+credentials will have the same permission as that of the AWS credentials.
+
+Parameters:
+ **DurationSeconds** (Integer/ Optional): The duration in seconds for which the
+ credentials should remain valid. Its default value is 3600. Its default max
+ value is 43200 which is can be configured using rgw sts max session duration.
+
+ **SerialNumber** (String/ Optional): The Id number of the MFA device associated
+ with the user making the GetSessionToken call.
+
+ **TokenCode** (String/ Optional): The value provided by the MFA device, if MFA is required.
+
+An administrative user needs to attach a policy to allow invocation of GetSessionToken API using its permanent
+credentials and to allow subsequent S3 operations invocation using only the temporary credentials returned
+by GetSessionToken.
+
+The user attaching the policy needs to have admin caps. For example::
+
+ radosgw-admin caps add --uid="TESTER" --caps="user-policy=*"
+
+The following is the policy that needs to be attached to a user 'TESTER1'::
+
+ user_policy = "{\"Version\":\"2012-10-17\",\"Statement\":[{\"Effect\":\"Deny\",\"Action\":\"s3:*\",\"Resource\":[\"*\"],\"Condition\":{\"BoolIfExists\":{\"sts:authentication\":\"false\"}}},{\"Effect\":\"Allow\",\"Action\":\"sts:GetSessionToken\",\"Resource\":\"*\",\"Condition\":{\"BoolIfExists\":{\"sts:authentication\":\"false\"}}}]}"
+
+
+STS Lite Configuration
+======================
+
+The following configurable options are available for STS Lite integration::
+
+ [client.radosgw.gateway]
+ rgw sts key = {sts key for encrypting the session token}
+ rgw s3 auth use sts = true
+
+The above STS configurables can be used with the Keystone configurables if one
+needs to use STS Lite in conjunction with Keystone. The complete set of
+configurable options will be::
+
+ [client.radosgw.gateway]
+ rgw sts key = {sts key for encrypting/ decrypting the session token}
+ rgw s3 auth use sts = true
+
+ rgw keystone url = {keystone server url:keystone server admin port}
+ rgw keystone admin project = {keystone admin project name}
+ rgw keystone admin tenant = {keystone service tenant name}
+ rgw keystone admin domain = {keystone admin domain name}
+ rgw keystone api version = {keystone api version}
+ rgw keystone implicit tenants = {true for private tenant for each new user}
+ rgw keystone admin password = {keystone service tenant user name}
+ rgw keystone admin user = keystone service tenant user password}
+ rgw keystone accepted roles = {accepted user roles}
+ rgw keystone token cache size = {number of tokens to cache}
+ rgw s3 auth use keystone = true
+
+The details of the integrating ldap with Ceph Object Gateway can be found here:
+:doc:`keystone`
+
+The complete set of configurables to use STS Lite with LDAP are::
+
+ [client.radosgw.gateway]
+ rgw sts key = {sts key for encrypting/ decrypting the session token}
+ rgw s3 auth use sts = true
+
+ rgw_s3_auth_use_ldap = true
+ rgw_ldap_uri = {LDAP server to use}
+ rgw_ldap_binddn = {Distinguished Name (DN) of the service account}
+ rgw_ldap_secret = {password for the service account}
+ rgw_ldap_searchdn = {base in the directory information tree for searching users}
+ rgw_ldap_dnattr = {attribute being used in the constructed search filter to match a username}
+ rgw_ldap_searchfilter = {search filter}
+
+The details of the integrating ldap with Ceph Object Gateway can be found here:
+:doc:`ldap-auth`
+
+Note: By default, STS and S3 APIs co-exist in the same namespace, and both S3
+and STS APIs can be accessed via the same endpoint in Ceph Object Gateway.
+
+Example showing how to Use STS Lite with Keystone
+=================================================
+
+The following are the steps needed to use STS Lite with Keystone. Boto 3.x has
+been used to write an example code to show the integration of STS Lite with
+Keystone.
+
+1. Generate EC2 credentials :
+
+.. code-block:: javascript
+
+ openstack ec2 credentials create
+ +------------+--------------------------------------------------------+
+ | Field | Value |
+ +------------+--------------------------------------------------------+
+ | access | b924dfc87d454d15896691182fdeb0ef |
+ | links | {u'self': u'http://192.168.0.15/identity/v3/users/ |
+ | | 40a7140e424f493d8165abc652dc731c/credentials/ |
+ | | OS-EC2/b924dfc87d454d15896691182fdeb0ef'} |
+ | project_id | c703801dccaf4a0aaa39bec8c481e25a |
+ | secret | 6a2142613c504c42a94ba2b82147dc28 |
+ | trust_id | None |
+ | user_id | 40a7140e424f493d8165abc652dc731c |
+ +------------+--------------------------------------------------------+
+
+2. Use the credentials created in the step 1. to get back a set of temporary
+ credentials using GetSessionToken API.
+
+.. code-block:: python
+
+ import boto3
+
+ access_key = <ec2 access key>
+ secret_key = <ec2 secret key>
+
+ client = boto3.client('sts',
+ aws_access_key_id=access_key,
+ aws_secret_access_key=secret_key,
+ endpoint_url=<STS URL>,
+ region_name='',
+ )
+
+ response = client.get_session_token(
+ DurationSeconds=43200
+ )
+
+3. The temporary credentials obtained in step 2. can be used for making S3 calls:
+
+.. code-block:: python
+
+ s3client = boto3.client('s3',
+ aws_access_key_id = response['Credentials']['AccessKeyId'],
+ aws_secret_access_key = response['Credentials']['SecretAccessKey'],
+ aws_session_token = response['Credentials']['SessionToken'],
+ endpoint_url=<S3 URL>,
+ region_name='')
+
+ bucket = s3client.create_bucket(Bucket='my-new-shiny-bucket')
+ response = s3client.list_buckets()
+ for bucket in response["Buckets"]:
+ print "{name}\t{created}".format(
+ name = bucket['Name'],
+ created = bucket['CreationDate'],
+ )
+
+Similar steps can be performed for using GetSessionToken with LDAP.
+
+Limitations and Workarounds
+===========================
+
+1. Keystone currently supports only S3 requests, hence in order to successfully
+authenticate an STS request, the following workaround needs to be added to boto
+to the following file - botocore/auth.py
+
+Lines 13-16 have been added as a workaround in the code block below:
+
+.. code-block:: python
+
+ class SigV4Auth(BaseSigner):
+ """
+ Sign a request with Signature V4.
+ """
+ REQUIRES_REGION = True
+
+ def __init__(self, credentials, service_name, region_name):
+ self.credentials = credentials
+ # We initialize these value here so the unit tests can have
+ # valid values. But these will get overridden in ``add_auth``
+ # later for real requests.
+ self._region_name = region_name
+ if service_name == 'sts':
+ self._service_name = 's3'
+ else:
+ self._service_name = service_name
+