On Tue, 23 Feb 2010 12:30:52 -0600 Ted Zlatanov <t...@lifelogs.com> wrote:
TZ> Can a Cassandra node be made read-only (as far as clients know)?
I realized I have another use case for read-only access besides backups:
On our network we have Cassandra readers, writers, and analyzers
(read+write). The writers and analyzers can run anywhere. The readers
can run anywhere too. I don't want the readers to have write access but
they should be able to read all keyspaces.
I think the best way to solve this is with an IAuthenticator change to
distinguish between full permissions and read-only permissions. Then
the Thrift API has to be modified to check for write access in only some
functions:
insert
batch_insert
remove
batch_mutate
I can make the necessary changes to the Avro API as well.
The work will require a change to login() to make it return an enum:
enum AuthorizedAccessLevel {
NONE = 0,
READ = 16,
WRITE = 32,
}
AuthorizedAccessLevel login(1: required string keyspace, 2:required
AuthenticationRequest auth_request) throws (1:AuthenticationException authnx,
2:AuthorizationException authzx),
...and that's pretty much it. Since login() used to be void, the change
is painless and will basically be a change of the loginDone ThreadLocal
in CassandraServer from Boolean to AuthorizedAccessLevel.
I left room between the enums in case we need future expansion,
e.g. "insert-only" for collectors that can't remove() or
batch_mutate().
Does this seem reasonable?
Thanks
Ted
