Granting privileges for data streams and index aliases

A data stream consists of one or more backing indices, which store the stream’s data. Most requests sent to a data stream are routed to one or more of these backing indices.

Similar to an index, you can use indices privileges to control access to a data stream. Any role or user granted privileges to a data stream are automatically granted the same privileges to its backing indices.

For example, my-data-stream consists of two backing indices: .ds-my-data-stream-2099.03.07-000001 and .ds-my-data-stream-2099.03.08-000002.

A user is granted the read privilege to my-data-stream.

{
  "names" : [ "my-data-stream" ],
  "privileges" : [ "read" ]
}

Because the user is automatically granted the same privileges to the stream’s backing indices, the user can retrieve a document directly from .ds-my-data-stream-2099.03.08-000002:

GET /.ds-my-data-stream-2099.03.08-000002/_doc/2

Later my-data-stream rolls over. This creates a new backing index: .ds-my-data-stream-2099.03.09-000003. Because the user still has the read privilege for my-data-stream, the user can retrieve documents directly from .ds-my-data-stream-2099.03.09-000003:

GET /.ds-my-data-stream-2099.03.09-000003/_doc/2

An index alias points to one or more indices, holds metadata and potentially a filter. The Elasticsearch security features treat aliases and indices the same. Privileges for indices actions are granted on specific indices or aliases. In order for an indices action to be authorized, the user that executes it needs to have permissions for that action on all the specific indices or aliases that the request relates to.

Let’s look at an example. Assuming we have an index called 2015, an alias that points to it called current_year, and a user with the following role:

{
  "names" : [ "2015" ],
  "privileges" : [ "read" ]
}

The user attempts to retrieve a document from current_year:

GET /current_year/event/1

The above request gets rejected, although the user has read privilege on the concrete index that the current_year alias points to. The correct permission would be as follows:

{
  "names" : [ "current_year" ],
  "privileges" : [ "read" ]
}

Unlike creating indices, which requires the create_index privilege, adding, removing and retrieving aliases requires the manage permission. Aliases can be added to an index directly as part of the index creation:

PUT /2015
{
  "aliases": {
    "current_year": {}
  }
}

or via the dedicated aliases api if the index already exists:

POST /_aliases
{
  "actions" : [
    { "add" : { "index" : "2015", "alias" : "current_year" } }
  ]
}

The above requests both require the manage privilege on the alias name as well as the targeted index, as follows:

{
  "names" : [ "20*", "current_year" ],
  "privileges" : [ "manage" ]
}

The index aliases api also allows also to delete aliases from existing indices. The privileges required for such a request are the same as above. Both index and alias need the manage permission.

Aliases can hold a filter, which allows to select a subset of documents that can be accessed out of all the documents that the physical index contains. These filters are not always applied and should not be used in place of document level security.