RGW Multi-tenancy

New in version Jewel.

The multi-tenancy feature allows to use buckets and users of the same name simultaneously by segregating them under so-called tenants. This may be useful, for instance, to permit users of Swift API to create buckets with easily conflicting names such as “test” or “trove”.

From the Jewel release onward, each user and bucket lies under a tenant. For compatibility, a “legacy” tenant with an empty name is provided. Whenever a bucket is referred without an explicit tenant, an implicit tenant is used, taken from the user performing the operation. Since the pre-existing users are under the legacy tenant, they continue to create and access buckets as before. The layout of objects in RADOS is extended in a compatible way, ensuring a smooth upgrade to Jewel.

Administering Users With Explicit Tenants

Tenants as such do not have any operations on them. They appear and disappear as needed, when users are administered. In order to create, modify, and remove users with explicit tenants, either an additional option –tenant is supplied, or a syntax “<tenant>$<user>” is used in the parameters of the radosgw-admin command.

Examples

Create a user testx$tester to be accessed with S3:

# radosgw-admin --tenant testx --uid tester --display-name "Test User" --access_key TESTER --secret test123 user create

Create a user testx$tester to be accessed with Swift:

# radosgw-admin --tenant testx --uid tester --display-name "Test User" --subuser tester:test --key-type swift --access full user create
# radosgw-admin --subuser 'testx$tester:test' --key-type swift --secret test123

Note

The subuser with explicit tenant has to be quoted in the shell.

Tenant names may contain only alphanumeric characters and underscores.

Accessing Buckets with Explicit Tenants

When a client application accesses buckets, it always operates with credentials of a particular user. As mentioned above, every user belongs to a tenant. Therefore, every operation has an implicit tenant in its context, to be used if no tenant is specified explicitly. Thus a complete compatibility is maintained with previous releases, as long as the referred buckets and referring user belong to the same tenant. In other words, anything unusual occurs when accessing another tenant’s buckets only.

Extensions employed to specify an explicit tenant differ according to the protocol and authentication system used.

S3

In case of S3, a colon character is used to separate tenant and bucket. Thus a sample URL would be:

https://ep.host.dom/tenant:bucket

Here’s a simple Python sample:

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     from boto.s3.connection import S3Connection, OrdinaryCallingFormat
     c = S3Connection(
             aws_access_key_id="TESTER",
             aws_secret_access_key="test123",
             host="ep.host.dom",
             calling_format = OrdinaryCallingFormat())
     bucket = c.get_bucket("test5b:testbucket")

Note that it’s not possible to supply an explicit tenant using a hostname. Hostnames cannot contain colons, or any other separators that are not already valid in bucket names. Using a period creates an ambiguous syntax. Therefore, the bucket-in-URL-path format has to be used.

Due to the fact that the native S3 API does not deal with multi-tenancy and radosgw’s implementation does, things get a bit involved when dealing with signed URLs and public read ACLs.

  • A signed URL does contain the AWSAccessKeyId query parameters, from which radosgw is able to discern the correct user and tenant owning the bucket. In other words, an application generating signed URLs should be able to take just the un-prefixed bucket name, and produce a signed URL that itself contains the bucket name without the tenant prefix. However, it is possible to include the prefix if you so choose.

    Thus, accessing a signed URL of an object bar in a container foo belonging to the tenant 7188e165c0ae4424ac68ae2e89a05c50 would be possible either via http://<host>:<port>/foo/bar?AWSAccessKeyId=b200fb6634c547199e436a0f93c0c46e&Expires=1542890806&Signature=eok6CYQC%2FDwmQQmqvY5jTg6ehXU%3D, or via http://<host>:<port>/7188e165c0ae4424ac68ae2e89a05c50:foo/bar?AWSAccessKeyId=b200fb6634c547199e436a0f93c0c46e&Expires=1542890806&Signature=eok6CYQC%2FDwmQQmqvY5jTg6ehXU%3D, depending on whether or not the tenant prefix was passed in on signature generation.

  • A bucket with a public read ACL is meant to be read by an HTTP client without including any query parameters that would allow radosgw to discern tenants. Thus, publicly readable objects must always be accessed using the bucket name with the tenant prefix.

    Thus, if you set a public read ACL on an object bar in a container foo belonging to the tenant 7188e165c0ae4424ac68ae2e89a05c50, you would need to access that object via the public URL http://<host>:<port>/7188e165c0ae4424ac68ae2e89a05c50:foo/bar.

Swift with built-in authenticator

TBD – not in test_multen.py yet

Swift with Keystone

In the default configuration, although native Swift has inherent multi-tenancy, radosgw does not enable multi-tenancy for the Swift API. This is to ensure that a setup with legacy buckets — that is, buckets that were created before radosgw supported multitenancy —, those buckets retain their dual-API capability to be queried and modified using either S3 or Swift.

If you want to enable multitenancy for Swift, particularly if your users only ever authenticate against OpenStack Keystone, you should enable Keystone-based multitenancy with the following ceph.conf configuration option:

rgw keystone implicit tenants = true

Once you enable this option, any newly connecting user (whether they are using the Swift API, or Keystone-authenticated S3) will prompt radosgw to create a user named <tenant_id>$<tenant_id, where <tenant_id> is a Keystone tenant (project) UUID — for example, 7188e165c0ae4424ac68ae2e89a05c50$7188e165c0ae4424ac68ae2e89a05c50.

Whenever that user then creates an Swift container, radosgw internally translates the given container name into <tenant_id>/<container_name>, such as 7188e165c0ae4424ac68ae2e89a05c50/foo. This ensures that if there are two or more different tenants all creating a container named foo, radosgw is able to transparently discern them by their tenant prefix.

Notes and known issues

Just to be clear, it is not possible to create buckets in other tenants at present. The owner of newly created bucket is extracted from authentication information.