Manifest for storage areas

Unlike the local and sync storage areas, the managed storage area requires its structure to be declared as JSON Schema and is strictly validated by Chrome. This schema must be stored in a file indicated by the "managed_schema" property of the "storage" manifest key and declares the enterprise policies supported by the extension.

Policies are analogous to options but are configured by a system administrator instead of the user, allowing the extension to be preconfigured for all users of an organization. See how Chrome handles policies for examples from Chrome itself.

After declaring the policies they can be read from the storage.managed API. It's up to the extension to enforce the policies configured by the administrator.

Sample manifest.json

The storage.managed_schema property indicates a file within the extension that contains the policy schema.

{
  "name": "My enterprise extension",
  "storage": {
    "managed_schema": "schema.json"
  },
  ...
}

Chrome will then load these policies from the underlying operating system and from Google Apps for signed-in users. The storage.onChanged event is fired whenever a policy change is detected, including while the browser wasn't running if the extension uses event pages. You can verify the policies that Chrome loaded at chrome://policy.

Schema format

The JSON Schema format has some additional requirements from Chrome:

• The top-level schema must have type object.
• The top-level object can't have additionalProperties. The properties declared are the policies for this extension.
• Each schema must have either a $ref value or exactly one type.

If the schema is invalid then Chrome won't load the extension and will indicate the reason why the schema wasn't validated. If a policy value does not conform to the schema then it will not be published by the storage.managed API.

Sample schema

{
  "type": "object",

  // "properties" maps an optional key of this object to its schema. At the
  // top-level object, these keys are the policy names supported.
  "properties": {

    // The policy name "AutoSave" is mapped to its schema, which in this case
    // declares it as a simple boolean value.
    // "title" and "description" are optional and are used to show a
    // user-friendly name and documentation to the administrator.
    "AutoSave": {
      "title": "Automatically save changes.",
      "description": "If set to true then changes will be automatically saved.",
      "type": "boolean"
    },

    // Other simple types supported include "integer", "string" and "number".
    "PollRefreshRate": {
      "type": "integer"
    },

    "DefaultServiceUrl": {
      "type": "string"
    },

    // "array" is a list of items that conform to another schema, described
    // in "items". An example to this schema is [ "one", "two" ].
    "ServiceUrls": {
      "type": "array",
      "items": {
        "type": "string"
      }
    },

    // A more complex example that describes a list of bookmarks. Each bookmark
    // has a "title", and can have a "url" or a list of "children" bookmarks.
    // The "id" attribute is used to name a schema, and other schemas can reuse
    // it using the "$ref" attribute.
    "Bookmarks": {
      "type": "array",
      "id": "ListOfBookmarks",
      "items": {
        "type": "object",
        "properties": {
          "title": { "type": "string" },
          "url": { "type": "string" },
          "children": { "$ref": "ListOfBookmarks" }
        }
      }
    },

    // An "object" can have known properties listed as "properties", and can
    // optionally have "additionalProperties" indicating a schema to apply to
    // keys that aren't found in "properties".
    // This example policy could map a URL to its settings. An example value:
    // {
    //   "youtube.com": {
    //     "blocklisted": true
    //   },
    //   "google.com": {
    //     "bypass_proxy": true
    //   }
    // }
    "SettingsForUrls": {
      "type": "object",
      "additionalProperties": {
        "type": "object",
        "properties": {
          "blocklisted": { "type": "boolean" },
          "bypass_proxy": { "type": "boolean" }
        }
      }
    }
  }
}