[[limitations]]
== Limitations

[float]
=== Plugins

Elasticsearch's plugin infrastructure is extremely flexible in terms of what can be extended. While it opens up Elasticsearch
to a wide variety of (often custom) additional functionality, when it comes to security, this high extensibility level
comes at a cost. We have no control over the third-party plugins' code (open source or not) and therefore we cannot
guarantee their compliance with Shield. For this reason, third-party plugins are not officially supported on clusters
with the Shield security plugin installed.

[float]
=== Changes in Index Wildcard Behavior

Elasticsearch clusters with the Shield security plugin installed apply the `/_all` wildcard, and all other wildcards,
to the indices that the current user has privileges for, not the set of all indices on the cluster. There are two
notable results of this behavior:

* Elasticsearch clusters with the Shield security plugin installed do not honor the `ignore_unavailable` option.
  This behavior means that requests involving indices that the current user lacks authorization for throw an
  `AuthorizationException` error, regardless of the option's setting.

* The `allow_no_indices` option is ignored, resulting in the following behavior: when the final set of indices after
  wildcard expansion and replacement is empty, the request throws a `IndexMissingException` error.

As a general principle, core Elasticsearch will return empty results in scenarios where wildcard expansion returns no
indices, while Elasticsearch with Shield returns exceptions. Note that this behavior means that operations with 
multiple items will fail the entire set of operations if any one operation throws an exception due to wildcard 
expansion resulting in an empty set of authorized indices.

[float]
=== Field and Document Level Security Limitations

Bulk updates do not work when document and field level security is enabled. If you are not using document and field level
security, bulk updates can be enabled by setting `shield.dls_fls.enabled` to `false`.

When document level security is enabled for an index:

* The get, multi get, termsvector and multi termsvector APIs aren't executed in real time. The realtime option for these APIs is forcefully set to false.
* Document level security isn't applied for APIs that aren't document based. An example is the field stats API.
* Document level security doesn't affect global index statistics that relevancy scoring uses. So this means that scores are computed without taking the role query into account.
  Note that documents not matching with the role query are never returned.
* The `has_child` and `has_parent` queries aren't supported as role query in the `roles.yml` file.
  The `has_child` and `has_parent` queries can be used in the search API with document level security enabled.

[float]
=== Document Expiration (_ttl)

Document expiration handled using the built-in {ref}/mapping-ttl-field.html#mapping-ttl-field[`_ttl` (time to live) mechanism]
does not work with Shield. The document deletions will fail and the documents continue to live past their expiration.

[float]
=== LDAP Realm

The <<ldap, LDAP Realm>> does not currently support the discovery of nested LDAP Groups.  For example, if a user is a member
of GroupA and GroupA is a member of GroupB, only GroupA will be discovered.  However, the <<active-directory, Active Directory Realm>> _does_ support transitive group membership.
