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115 lines
3.9 KiB
ReStructuredText
115 lines
3.9 KiB
ReStructuredText
Access control basics
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=====================
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.. contents:: Table of contents
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:backlinks: none
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:depth: 2
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:local:
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Introduction
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------------
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To understand the basics of access control in Hasura, let's take a look at this analogy to a SQL query:
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.. thumbnail:: ../../../../img/graphql/manual/auth/permissions-rule-analogy.png
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:width: 70%
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This query returns the right set of results by defining the requirements for columns and rows in a given
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table. Hasura's rule-based access control works similary - you define the following permissions for a
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combination of **role**, **table** and **action** (*insert, update, select and delete*):
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**Row-level permissions**
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Limit access to a subset of the rows in the table based on this permission. Row-level permissions are
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essentially boolean expressions that, when evaluated against any row, determine access to it. These
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permissions are constructed from the values in columns, :doc:`session variables <roles-variables>` and
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static values to build this boolean expression.
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**Column-level permissions**
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For the rows that are accessible based on the above, limit access to a subset of the columns based on
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this permission rule.
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.. admonition:: More information
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For details on all the configuration options, see :doc:`permission-rules`.
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Example
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-------
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Let's see access control in action using a simple example.
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Create a table
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^^^^^^^^^^^^^^
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Head to your console and :ref:`create a table <create-tables>` called ``author`` with the following
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schema:
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.. code-block:: sql
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author (
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id INT PRIMARY KEY,
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name TEXT
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)
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Now, insert some sample data into the table using the ``Insert Row`` tab of the ``author`` table.
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Run a query **without** access control
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Head to the ``GraphiQL`` tab in your console and try out the below query:
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.. code-block:: graphql
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query {
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author {
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id
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name
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}
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}
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You'll see that this results in a response that contains all the authors because by default the GraphQL
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query is accepted with **admin** permissions.
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.. thumbnail:: ../../../../img/graphql/manual/auth/fetch-authors.png
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Define access control rules
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^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Now let's define an access control rule for the ``author`` table for a role ``users``. Head to the
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**Permissions** section of the table (``Data`` --> <table> --> ``Permissions`` tab) and define permissions
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as shown below:
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.. thumbnail:: ../../../../img/graphql/manual/auth/permission-basics-simple-example.png
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This permission rule reads as: "*For the role* ``user`` *, table* ``author`` *and operation* ``select``/``query``,
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allow access to those rows where the value in the ``id`` *column is the same as the value in the*
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``X-Hasura-User-ID`` *session variable*".
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Run a query **with** access control
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Let's run the same query as above but now with the ``X-Hasura-Role`` and ``X-Hasura-User-ID`` session
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variables also included to indicate role and user information. These session variables are passed in
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the ``Request Headers`` section of ``GraphiQL`` as highlighted below:
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.. thumbnail:: ../../../../img/graphql/manual/auth/permission-basics-query-with-access-control.png
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As you can see, the results are now filtered based on the access control rule for the role ``user``
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(*since that is the role indicated by the* ``X-Hasura-Role`` *session variable*) and the results are
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restricted to only those rows where the value in the ``id`` column is equal to ``1`` (*as indicated by
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the* ``X-Hasura-User-ID`` *session variable*).
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As described in the :doc:`Introduction to Authentication and Authorization <index>` section of the docs,
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your auth service is required to resolve authentication tokens into these session variables. See
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:doc:`Reference - Session Variables<index>` for more details.
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Next steps
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----------
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Read about roles and session variables at: :doc:`roles-variables`
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See more detailed examples at: :doc:`Common access control examples<common-roles-auth-examples>`
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