Validating and testing policies

Validating policies

You can use the Cerbos compiler to make sure that your policies are valid before pushing them to a production Cerbos instance. We recommend setting up a git hook or a CI step to run the Cerbos compiler before you push any policy changes to production.

docker run -i -t -v /path/to/policy/dir:/policies ghcr.io/cerbos/cerbos:0.43.0 compile /policies

Testing policies

You can write optional tests for policies and run them as part of the compilation stage to make sure that the policies do exactly what you expect.

Tests are defined using the familiar YAML format as well. A test file must have _test suffix in the name and one of the following file extensions: yaml, yml, or json. For example, album_test.yml, album_test.yaml or album_test.json.

Test suite definition

---
name: AlbumObjectTestSuite (1)
description: Tests for verifying the album:object resource policy (2)
options:
  now: "2022-08-02T15:00:00Z" (3)
  defaultPolicyVersion: staging (4)
  lenientScopeSearch: true (5)
  globals: (6)
    my_global_var: foo

principals: (7)
  alicia:
    id: aliciaID
    roles:
      - user

bradley:
    id: bradleyID
    roles:
      - user

principalGroups: (8)
  everyone:
    principals:
      - alicia
      - bradley

resources: (9)
  alicia_album:
    id: XX125
    kind: album:object
    policyVersion: default
    attr:
      owner: aliciaID
      public: false
      flagged: false

bradley_album:
    id: XX250
    kind: album:object
    policyVersion: staging
    attr:
      owner: bradleyID
      public: false
      flagged: false

resourceGroups: (10)
  all_albums:
    resources:
      - alicia_album
      - bradley_album

auxData: (11)
  validJWT:
    jwt:
      iss: my.domain
      aud: ["x", "y"]
      myField: value

tests: (12)
  - name: Accessing an album (13)
    options: (14)
      now: "2022-08-03T15:00:00Z" (15)
      defaultPolicyVersion: production (16)
      lenientScopeSearch: false (17)
      globals: (18)
        my_global_var: bar

input: (19)
      principals: (20)
        - alicia
        - bradley
      resources: (21)
        - alicia_album
        - bradley_album
      actions: (22)
        - view
        - delete
      auxData: validJWT (23)

expected: (24)
      - principal: alicia (25)
        resource: alicia_album (26)
        actions: (27)
          view: EFFECT_ALLOW
          delete: EFFECT_ALLOW
        outputs: (28)
          - action: view (29)
            expected: (30)
              - src: resource.album.vdefault#view-rule
                val:
                  key1: value1
                  key2: ["value2", "value3"]
              - src: resource.album.vdefault#token-lifetime
                val: 1h

- principal: bradley
        resource: bradley_album
        actions:
          view: EFFECT_ALLOW
          delete: EFFECT_ALLOW

- name: Using groups
    input:
      principalGroups: (31)
        - everyone
      resourceGroups: (32)
        - all_albums
      actions:
        - download

expected:
      - principalGroups: (33)
          - everyone
        resourceGroups: (34)
          - all_albums
        actions:
          download: EFFECT_DENY

Sharing test fixtures

It is possible to share principals, resources and auxData blocks between test suites stored in the same directory. Create a testdata directory in the directory containing your test suite files, then define shared resources, principals and auxData in testdata/resources.yml, testdata/principals.yml, testdata/auxdata.yml respectively (yaml and json extensions are also supported).

tests
├── album_object_test.yaml
├── gallery_object_test.yaml
├── slideshow_object_test.yaml
└── testdata
   ├── auxdata.yaml
   ├── principals.yaml
   └── resources.yaml

An example of testdata/principals.yml

---
principals: # required
  john:
    id: johnID
    roles:
      - user
      - moderator

principalGroups: # optional
  moderators:
    principals:
      - john

An example of testdata/resources.yml

---
resources: # required
  alicia_album:
    id: XX125
    kind: "album:object"
    attr:
      owner: aliciaID
      public: false
      flagged: false

resourceGroups: # optional
  all_albums:
    resources:
      - alicia_album

An example of testdata/auxdata.yml

---
auxData: # required
  validJWT:
    jwt:
      iss: my.domain
      aud: ["x", "y"]
      myField: value

| | YAML anchors and overrides are a great way to reduce repetition and reuse definitions in test cases.