Access Control Model

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    An introduction to access control in Sync Gateway

    Related Concepts: Access Control Model | Channels | Roles | Sync Function | Users

    Concept

    You control document access by routing it to a channel and by making that channel accessible to the users or roles you want to be able to access documents of that type.

    Model

    In the Couchbase Mobile ecosystem access to documents is governed by three key entities: users, roles and channels.

    Access Control Model

    Access

    Conceptually, the channel can be considered as a tag associated with a document. Every document processed by the Sync Gateway is assigned to a channel (user-defined or system-defined). A channel is the fundamental way to segregate documents and for enforcing access control.

    Every Sync Gateway user is granted access to zero, one or more channels. It is the channels membership that determines the documents users can access — as illustrated in Access Control Model

    A Sync Gateway role is a way of logically grouping users. Like the channel, a role is granted access to zero, one or more channels.

    A user can only read documents that are in at least one of their assigned channels; whether directly or as part of an assigned role.

    Context

    You control document access by routing it to a channel and by making that channel accessible to the users or roles you want to be able to access documents of that type.

    Sync Gateway

    All users can implicitly access any document in the public channel. In addition, there can be user-defined channels that users can be assigned to.

    Once a user is granted access to a new channel, the next replication pull request from the client will retrieve all documents to which the user now has access.

    Revoking access to a channel means that users who previously used the channel to get replicated documents will no longer see any synced updates.

    Note that access grants neither confer, nor constrain, the type of access. Instead you can explicitly implement write access controls within the Sync Function; perhaps restricting updates to specific users or roles — for more on this see Control Write Access.

    Couchbase Lite

    By default, Couchbase Lite gets all the channels to which the configured user account has access. Optionally, a Couchbase Lite "pull" replication can also specify a comma-separated list of channel names to receive documents from. In this case, the replication from Sync Gateway will only pull documents tagged with those channels. Client apps can use this ability to intelligently sync with a subset of the available documents from the database.

    Channel Access Revocation

    3.0 Breaking Change
    Whenever a user loses access to a channel (or channels) all document in the channel(s) are auto-purged from local Couchbase Lite databases.
    In Sync Gateway 2.x these documents remain in the local database on channel access loss.

    Users may lose access to documents for many reasons, including:

    • The User loses direct access to channel

    • The User is removed from a role

    • A role the user belongs to is revoked access to channel

    By default, when a user loses access to a channel, the next Couchbase Lite Pull replication auto-purges all documents in the channel from local Couchbase Lite databases (on devices belonging to the user) unless they belong to any of the user’s other channels — see: Table 1.

    Table 1. Sync Gateway behavior following access revocation
    System State Impact on Sync

    Replication Type

    Access Control on Sync Gateway

    Expected behavior (auto-purge enabled- default)

    Pull only

    User revoked access to channel.

    Sync Function includes requireAccess(revokedChannel)

    Previously synced documents are auto purged on local

    Push only

    User revoked access to channel.

    Sync Function includes requireAccess(revokedChannel)

    No impact of auto-purge

    Documents get pushed but will be rejected by Sync Gateway

    Push-pull

    User revoked access to channel

    Sync Function includes requireAccess(revokedChannel)`

    Previously synced documents are auto purged on Couchbase Lite.

    Local changes continue to be pushed to remote but are rejected by Sync Gateway

    Provisioning

    • Channel — the channels topic discusses how channels are created and how documents can be assigned to channels.

    • User — the user topic discusses provisioning of users and providing users access to channels.

    • Role — the role topic discusses roles, assignment of users to roles created and providing roles access to channels.