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Auth0 Fine Grained Authorization (FGA) Concepts

note
Auth0 Fine Grained Authorization (FGA) is the early-stage product we are building at Auth0 to solve fine-grained authorization at scale. Sign up for the Developer Community Preview to try it out, and join our Discord community if you are interested in learning more about our plans.

Please note that at this point in time, it is not considered production-ready and does not come with any SLAs; availability and uptime are not guaranteed. Limitations of Auth0 FGA during the Developer Community Preview can be found here.

The Auth0 FGA service answers authorization checks by determining whether a relationship exists between an object and a user and takes into consideration the authorization model of the system and the relationship tuples present in the system at that time in order to make a decision.

In this guide you will learn about the most relevant FGA concepts, such as a type or an authorization model, and you will be able to explore them using the FGA playground.

The Playground

Try this guide out on the Auth0 FGA Playground

What is a type?​

A type is a class of objects that have similar characteristics.

Examples of types:

  • workspace
  • repository
  • organization
  • document

What is a type definition?​

A type definition is a configuration that defines all possible relations a user or another object can have in relation to this type.

Code snippet below is an example of a type definition:

type document
  relations
    define viewer as self
    define commenter as self
    define editor as self
    define owner as self

What is an authorization model?​

An authorization model is a combination of one or more type definitions. This is used to define the permission model of a system.

Code snippet below is an example of an authorization model:

type document
  relations
    define viewer as self
    define commenter as self
    define editor as self
    define owner as self
type domain
  relations
    define member as self

Authorization model, together with relationship tuples, allow determination of whether a relationship exists between a user and an object.

The Auth0 Fine Grained Authorization (FGA) service has two different syntaxes to define the authorization model:

  • A JSON syntax accepted by the Auth0 FGA API that follows closely the original syntax discussed in the Zanzibar Paper. See Equivalent Zanzibar Concepts.
  • A DSL that we believe is easier to use and is used in the Auth0 FGA Playground to help with modeling. This is translated to the API-supported syntax before being sent to the API.

Learn more about the Auth0 FGA Configuration Language.

What is a store?​

A store is a Auth0 Fine Grained Authorization (FGA) organization entity that owns authorization model.

A store contains all your data, including authorization model and relationship tuples.

What is an object?​

An object represents an entity in the system. We can define how various users have a relationship to it through relationship tuples and the authorization model.

The object name is a combination of the type and an identifier of the object.

For example:

  • workspace:fb83c013-3060-41f4-9590-d3233a67938f
  • repository:auth0/express-jwt
  • organization:org_ajUc9kJ
  • document:new-roadmap

User, relation and object are the building blocks for relationship tuples.

For more information, please see Modeling Basics.

What is a user?​

A user is an entity in the system that can be related to an object.

A user is

  • any user: e.g. anne or 4179af14-f0c0-4930-88fd-5570c7bf6f59
  • any object: e.g. workspace:fb83c013-3060-41f4-9590-d3233a67938f, repository:auth0/express-jwt or organization:org_ajUc9kJ
  • a group or a set of users (also called a userset): e.g. organization:org_ajUc9kJ#members, which represents the set of users related to the object organization:org_ajUc9kJ as member
  • everyone, using the special syntax: *

User, relation and object are the building blocks for relationship tuples.

For more information, please see Modeling Basics.

What is a relation?​

A relation is a string defined in the type definition of an authorization model that defines the possibility of a relationship between objects of this type and other users in the system.

Examples of relation:

  • User can be a reader a document
  • Team can administer a repo
  • User can be a member of a team

What is a relation definition?​

A relation definition lists the conditions or requirements under which this relationship would be possible.

For example:

  • editor describing a possible relationship between a user and an object in the document type allows the following:
    • user identifier to object relationship: the user id anne is related to the object document:roadmap as editor
    • object to object relationship: the object application:ifft is related to the object document:roadmap as editor
    • userset to object relationship: the userset organization:auth0.com#member is related to document:roadmap as editor
      • indicating that the set of users who are related to the object organization:auth0.com as member are related to the object document:roadmap as editors
      • this allows for potential solutions to use-cases like sharing a document internally with all members of a company or a team
    • everyone to object relationship: everyone (*) is related to document:roadmap as editor
      • this allows for solution to use-cases such as having a document publicly editable

These would be defined in the authorization model as such:

type document
  relations
    define viewer as self
    define commenter as self
    define editor as self
    define owner as self
info

In the configuration of the document type, we have four relations: viewer, commenter, editor and owner.

User, relation and object are the building blocks for relationship tuples.

For more information, please see Modeling Basics.

What is a relationship tuple?​

A relationship tuple is a grouping consisting of a user, a relation and an object stored in Auth0 FGA .

A relationship tuple consists of a grouping of:

  • user, e.g. anne, 3f7768e0-4fa7-4e93-8417-4da68ce1846c, workspace:auth0 or folder:planning#editor
  • relation, e.g. editor, member or parent_workspace
  • object, e.g repo:auth0/express_jwt, domain:auth0.com or channel:marketing

An authorization model, together with relationship tuples, allow the determination of whether a relationship exists between a user and an object.

Throughout the documentation, you will encounter relationship tuples represented as:

[
  {
    "user": "anne",
    "relation": "editor",
    "object": "document:new-roadmap",
  },
]

For more information, please see Modeling Basics.

What is a relationship?​

A relationship is the realization of a relation between a user and an object.

An authorization model, together with relationship tuples, allow the determination of whether a relationship exists between a user and an object. Relationships may be classified as direct or implied.

What are direct and implied relationships?​

A direct relationship R between user X and object Y means the relationship tuple (user=X, relation=R, object=Y) exists, and the Auth0 FGA authorization model for that relation allows this direct relationship (by use of self).

An implied relationship R exists between user X and object Y if user X is related to an object Z that is in direct or implied relationship with object Y, and the Auth0 FGA authorization model allows it.

  • anne has a direct relationship with document:new-roadmap as viewer if the type definition allows it (allows self), and one of the following relationship tuples exist:

    • [
        // Anne is directly related to the document
        {
          "user": "anne",
          "relation": "viewer",
          "object": "document:new-roadmap",
        },
      ]
    • [
        // Everyone (`*`) is directly related to the document
        {
          "user": "*",
          "relation": "viewer",
          "object": "document:new-roadmap",
        },
      ]
    • [
        // The userset is directly related to this document
        {
          "user": "team:product#member",
          "relation": "viewer",
          "object": "document:new-roadmap",
        },
        // AND Anne is a member of a userset (e.g. team:product#member)
        {
          "user": "anne",
          "relation": "member",
          "object": "team:product#member",
        },
      ]

  • anne has an implied (also called computed) relationship with document:new-roadmap as viewer if the type definition allows it, and the presence of relationship tuples satisfying the relationship exist.

    For example, assuming the following type definition:

    type document
      relations
        define viewer as self or editor
        define editor as self

    And assuming the following relationship tuple exists in the system:

    [
      {
        "user": "anne",
        "relation": "editor",
        "object": "document:new-roadmap",
      },
    ]

    In this case, the relationship between anne and document:new-roadmap as a viewer is implied from the editor relationship anne has with that same document. There does not exist any relationship tuple indicating that anne is directly related to the document as a viewer. Thus, the following request to check whether a viewer relationship exists between anne and document:new-roadmap will return true.

    Initialize the SDK
    // FGA_ENVIRONMENT can be "us" (default if not set) for Developer Community Preview or "playground" for the Playground API
    // import the SDK
    const { Auth0FgaApi } = require('@auth0/fga');

    // Initialize the SDK
    const fgaClient = new Auth0FgaApi({
      environment: process.env.FGA_ENVIRONMENT,
      storeId: process.env.FGA_STORE_ID,
      clientId: process.env.FGA_CLIENT_ID,
      clientSecret: process.env.FGA_CLIENT_SECRET,
    });

    // Run a check
    const { allowed } = await fgaClient.check({
      tuple_key: {
        user: 'anne',
        relation: 'viewer',
        object: 'document:new-roadmap',
      },});

    // allowed = true

What is a check request?​

A check request is a call to the Auth0 Fine Grained Authorization (FGA) API endpoint that returns whether the user has a certain relationship with an object.

This can be done using the check methods in the Auth0 FGA SDKs (JavaScript SDK/Go SDK/.NET SDK) or by manually calling the check endpoint using curl or in your code.

The check endpoint responds with { "allowed": true } if a relationship exists, and with { "allowed": false } if the relationship does not.

For example, the following will check whether anne has viewer relation to document:new-roadmap:

Initialize the SDK
// FGA_ENVIRONMENT can be "us" (default if not set) for Developer Community Preview or "playground" for the Playground API
// import the SDK
const { Auth0FgaApi } = require('@auth0/fga');

// Initialize the SDK
const fgaClient = new Auth0FgaApi({
  environment: process.env.FGA_ENVIRONMENT,
  storeId: process.env.FGA_STORE_ID,
  clientId: process.env.FGA_CLIENT_ID,
  clientSecret: process.env.FGA_CLIENT_SECRET,
});

// Run a check
const { allowed } = await fgaClient.check({
  tuple_key: {
    user: 'anne',
    relation: 'viewer',
    object: 'document:new-roadmap',
  },});

// allowed = true

For more information, please see Comparison between check, read and expand and Check API Request Documentation.

What are contextual tuples?​

Contextual tuples are tuples that are sent alongside a check request, and only exist within the context of that particular request.

Similar to relationship tuples, contextual tuples are composed of a user, relation and object.

Unlike relationship tuples, they are not written to the system state. If contextual tuples are sent alongside a check request, they are treated as if they are true (treated as as if they are relationship tuples that have been written to the system state).

For more information, please see Contextual and Time-Based Authorization, Authorization Through Organization Context and Check API Request Documentation.

How do I represent "everyone"?​

In Auth0 Fine Grained Authorization (FGA) the special * syntax means everyone when used as user in a relationship tuple.

For example, in a case where you would like to indicate a certain document document:new-roadmap is publicly writable (i.e. has everyone as an editor), you can add the following relationship tuple:

[
  {
    "user": "*",
    "relation": "editor",
    "object": "document:new-roadmap",
  },
]

Note that * has no special meaning when used in other contexts. For example, workspace:* as a user or object means a single object with the type workspace and the object_id the string *. For more information, please see Modeling Public Access and Advanced Modeling: Modeling Google Drive.

Check the following sections for more on how object-to-object relationships can be used.
Auth0 FGA Concepts

Learn about the Auth0 FGA Concepts

Modeling Basics

Get started with modeling your permission system in Auth0 FGA

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