[Preview] Inherited roles for postgres read queries
fixes #3868
docker image - `hasura/graphql-engine:inherited-roles-preview-48b73a2de`
Note:
To be able to use the inherited roles feature, the graphql-engine should be started with the env variable `HASURA_GRAPHQL_EXPERIMENTAL_FEATURES` set to `inherited_roles`.
Introduction
------------
This PR implements the idea of multiple roles as presented in this [paper](https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/FGALanguageICDE07.pdf). The multiple roles feature in this PR can be used via inherited roles. An inherited role is a role which can be created by combining multiple singular roles. For example, if there are two roles `author` and `editor` configured in the graphql-engine, then we can create a inherited role with the name of `combined_author_editor` role which will combine the select permissions of the `author` and `editor` roles and then make GraphQL queries using the `combined_author_editor`.
How are select permissions of different roles are combined?
------------------------------------------------------------
A select permission includes 5 things:
1. Columns accessible to the role
2. Row selection filter
3. Limit
4. Allow aggregation
5. Scalar computed fields accessible to the role
Suppose there are two roles, `role1` gives access to the `address` column with row filter `P1` and `role2` gives access to both the `address` and the `phone` column with row filter `P2` and we create a new role `combined_roles` which combines `role1` and `role2`.
Let's say the following GraphQL query is queried with the `combined_roles` role.
```graphql
query {
employees {
address
phone
}
}
```
This will translate to the following SQL query:
```sql
select
(case when (P1 or P2) then address else null end) as address,
(case when P2 then phone else null end) as phone
from employee
where (P1 or P2)
```
The other parameters of the select permission will be combined in the following manner:
1. Limit - Minimum of the limits will be the limit of the inherited role
2. Allow aggregations - If any of the role allows aggregation, then the inherited role will allow aggregation
3. Scalar computed fields - same as table column fields, as in the above example
APIs for inherited roles:
----------------------
1. `add_inherited_role`
`add_inherited_role` is the [metadata API](https://hasura.io/docs/1.0/graphql/core/api-reference/index.html#schema-metadata-api) to create a new inherited role. It accepts two arguments
`role_name`: the name of the inherited role to be added (String)
`role_set`: list of roles that need to be combined (Array of Strings)
Example:
```json
{
"type": "add_inherited_role",
"args": {
"role_name":"combined_user",
"role_set":[
"user",
"user1"
]
}
}
```
After adding the inherited role, the inherited role can be used like single roles like earlier
Note:
An inherited role can only be created with non-inherited/singular roles.
2. `drop_inherited_role`
The `drop_inherited_role` API accepts the name of the inherited role and drops it from the metadata. It accepts a single argument:
`role_name`: name of the inherited role to be dropped
Example:
```json
{
"type": "drop_inherited_role",
"args": {
"role_name":"combined_user"
}
}
```
Metadata
---------
The derived roles metadata will be included under the `experimental_features` key while exporting the metadata.
```json
{
"experimental_features": {
"derived_roles": [
{
"role_name": "manager_is_employee_too",
"role_set": [
"employee",
"manager"
]
}
]
}
}
```
Scope
------
Only postgres queries and subscriptions are supported in this PR.
Important points:
-----------------
1. All columns exposed to an inherited role will be marked as `nullable`, this is done so that cell value nullification can be done.
TODOs
-------
- [ ] Tests
- [ ] Test a GraphQL query running with a inherited role without enabling inherited roles in experimental features
- [] Tests for aggregate queries, limit, computed fields, functions, subscriptions (?)
- [ ] Introspection test with a inherited role (nullability changes in a inherited role)
- [ ] Docs
- [ ] Changelog
Co-authored-by: Vamshi Surabhi <6562944+0x777@users.noreply.github.com>
GitOrigin-RevId: 3b8ee1e11f5ceca80fe294f8c074d42fbccfec63
2021-03-08 14:14:13 +03:00
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type: bulk
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args:
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- type: pg_track_table
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args:
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table: employee
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- type: pg_track_table
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args:
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table: team
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- type: pg_track_table
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args:
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table: manager
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#Object relationship
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- type: pg_create_object_relationship
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args:
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name: manager
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table: employee
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using:
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foreign_key_constraint_on: manager_id
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#Array relationship
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- type: pg_create_array_relationship
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args:
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table: manager
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name: employees
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using:
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foreign_key_constraint_on:
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table: employee
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column: manager_id
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- type: pg_add_computed_field
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args:
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table: employee
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name: yearly_salary
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definition:
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function: employee_yearly_salary
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table_argument: employee_row
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- type: pg_create_select_permission
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args:
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table: employee
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role: employee
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permission:
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columns:
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- id
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- name
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- salary
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- title
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- team_id
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computed_fields:
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- yearly_salary
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filter:
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id:
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_eq: X-Hasura-User-Id
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- type: pg_create_select_permission
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args:
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table: employee
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role: manager
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permission:
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columns:
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- name
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- title
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- manager_remarks
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filter:
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manager_id:
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_eq: X-Hasura-Manager-Id
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allow_aggregations: true
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- type: pg_create_select_permission
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args:
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table: manager
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role: manager
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permission:
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columns: '*'
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allow_aggregations: true
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filter:
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id: X-Hasura-Manager-Id
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- type: pg_create_select_permission
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args:
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table: manager
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role: employee
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permission:
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columns:
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- name
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- phone
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allow_aggregations: true
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filter:
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employees:
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manager_id:
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_eq: X-Hasura-Manager-Id
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- type: add_inherited_role
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args:
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role_name: manager_employee
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role_set:
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- manager
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- employee
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2021-03-18 18:28:25 +03:00
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- type: pg_track_table
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args:
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table: authors
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- type: pg_track_table
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args:
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table: articles
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- type: pg_create_select_permission
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args:
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table: authors
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role: author
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permission:
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columns:
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- id
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- name
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- followers
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allow_aggregations: false
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filter:
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id: X-Hasura-Author-Id
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- type: pg_create_select_permission
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args:
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table: authors
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role: editor
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permission:
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columns:
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- name
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- followers
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allow_aggregations: true
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filter: {}
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- type: pg_create_select_permission
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args:
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table: articles
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role: guest
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permission:
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columns:
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- title
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- content
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- author_id
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allow_aggregations: true
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filter:
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is_published: true
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- type: pg_create_select_permission
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args:
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table: articles
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role: author
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permission:
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columns: "*"
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allow_aggregations: true
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filter:
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author_id: X-Hasura-Author-Id
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- type: pg_create_select_permission
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args:
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table: articles
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role: editor
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permission:
|
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columns: "*"
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filter: {}
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- type: add_inherited_role
|
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args:
|
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role_name: author_editor_guest_inherited_role
|
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role_set:
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- author
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- editor
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- guest
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