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diff --git a/toolkit/mozapps/extensions/docs/AMRemoteSettings-overview.rst b/toolkit/mozapps/extensions/docs/AMRemoteSettings-overview.rst new file mode 100644 index 0000000000..e22c1fcc12 --- /dev/null +++ b/toolkit/mozapps/extensions/docs/AMRemoteSettings-overview.rst @@ -0,0 +1,162 @@ +AMRemoteSettings Overview +========================= + +``AMRemoteSettings`` is a singleton that is responsible for fetching data from a RemoteSettings collection named +``"main/addons-manager-settings"`` to remotely control a set of Add-ons related preferences (hardcoded inside +the AMRemoteSettings definition part of a given Firefox release). + +``AMRemoteSettings`` will process the collection data when the RemoteSettings ``"sync"`` event is fired and on +late browser startup if there is already some data stored locally in the collection (and so if the pref value is +manually changed, then it would be set again to the value stored in the RemoteSettings collection data, either +on the next browser startup or on the next time the ``"sync"`` event is fired again). + +.. warning:: + Any about:config preference that AMRemoteSettings singleton sets while processing the RemoteSettings collection data + are **never cleared automatically** (e.g. if in a future Firefox version AMRemoteSettings does not handle a particular + settings anymore, or if the RemoteSettings entry is removed from the collection on the RemoteSettings service side). + + In practice this makes this feature a good choice when the remotely controlled about:config preferences is related to: + + * Firefox Add-ons features in the process of being deprecated and then fully removed in a future Firefox release + + * or controlled settings that are never removed from the ``"main/addons-manager-settings"`` collection. + + In general before changing controlled settings in the ``"main/addons-manager-settings"`` collection it is advisable to: + + * make sure to default value for the related about:config preferences has been changed in mozilla-central first, + and to let it ride the release train and get some backing time on release; + + * only after that consider changing the value controlled by ``"main/addons-manager-settings"`` collection, + to set the same value on older Firefox releases where the previous default value was set. + +The ``AMRemoteSettings`` singleton queries RemoteSettings and processes all the entries got from the +``"main/addons-manager-settings"`` collection, besides entries that may be filtered out by RemoteSettings based on +the ``"filter_expression"`` property (See https://remote-settings.readthedocs.io/en/latest/target-filters.html#how). + +Each of the entries created in the ``"main/addons-manager-settings"`` collection and is expected to match the JSONSchema +described in the :ref:`JSON Schema section below<JSON Schema>`. + +For each entry found in the collection, only the properties that are explicitly included in the +``AMRemoteSettings.RS_ENTRIES_MAP`` object are going to be processed (e.g. new Firefox versions may have introduced new +ones that older Firefox version will just ignore): + +* Each of the ``AMRemoteSettings.RS_ENTRIES_MAP`` properties: + + * represents a group of settings (e.g. the property named ``"installTriggerDeprecation"``) is responsible of controlling + about:config preferences related to the InstallTrigger deprecation + + * is set to an array of string, which lists the about:config preferences names that can actually be controlled by the + related group of settings (e.g. ``"installTriggerDeprecation"`` can only control two preferences, + ``"extensions.InstallTrigger.enabled"`` and ``"extensions.InstallTriggerImpl.enabled"``, that are controlling the + InstallTrigger and InstallTrigger's methods availability). + +.. warning:: + Any other about:config preference names that are not listed explicitly in the ``AMRemoteSettings.RS_ENTRIES_MAP`` config + is expected to be ignored, even if allowed by a new version of the collection's JSONSchema (this is the expected behavior + and prevents the introduction of unexpected behaviors on older Firefox versions that may not be expecting new settings groups + that may be introduced in Firefox releases that followed it). + + Any about:config preference with an unexpected value type is going to be ignored as well (look to the ``AMRemoteSettings.processEntries`` + to confirm which preferences values types are already expected and handled accordingly). + +.. _Controlled Settings Groups: + +AMRemoteSettings - Controlled Settings Groups +============================================= + +installTriggerDeprecation +------------------------- + +Group of settings to control InstallTrigger deprecation (Bug 1754441) + +- **extensions.InstallTrigger.enabled** (boolean), controls the availability of the InstallTrigger global: + + - Turning this to false will be hiding it completely + + .. note:: + Turning this off can potentially impact UA detection on website being using it to detect + Firefox. The WebCompat team should be consulted before setting this to `false` by default in + Nightly or across all Firefox >= 100 versions through the ``"addons-manager-settings"`` + RemoteSettings collection). + +- **extensions.InstallTriggerImpl.enabled** (boolean): controls the availability of the InstallTrigger methods: + + - Turning this to false will hide all the InstallTrigger implementation, preventing using it to + trigger the addon install flow, while the InstallTrigger global will still exists but be set to null. + +How to define new remotely controlled settings +---------------------------------------------- + +.. note:: + Please update the :ref:`JSON Schema` and :ref:`UI Schema` in this documentation page updated when the ones used on the + RemoteSettings service side have been changed, and document new controlled settings in the section :ref:`Controlled Settings Groups`. + +* Confirm that the :ref:`JSON Schema` and :ref:`UI Schema` included in this page are in sync with the one actually used on the + RemoteSettings service side, and use it as the starting point to update it to include a new type on remotely controlled setting: + + * choose a new unique string for the group of settings to be used in the ``definitions`` and ``properties`` + objects (any that isn't already used in the existing JSON Schema ``definitions``), possibly choosing a name + that helps to understand what the purpose of the entry. + + * add a new JSONSchema for the new group of settings in the ``definitions`` property + + * each of the properties included in the new definition should be named after the name of the about:config pref + being controlled, their types should match the type expected by the pref (e.g. ``"boolean"`` for a boolean preference). + + * make sure to add a description property to the definition and to each of the controlled preferences, which should + describe what is the settings group controlling and what is the expected behavior on the values allowed. + +* Add a new entry to ``"AMRemoteSettings.RS_ENTRIES_MAP"`` with the choosen ``"id"`` as its key and + the array of the about:config preferences names are its value. + +* If the value type of a controlled preference isn't yet supported, the method ``AMRemoteSettings.processEntries`` has to be + updated to handle the new value type (otherwise the preference value will be just ignored). + +* Add a new test to cover the expected behaviors on the new remotely controlled settings, the following RemoteSettings + documentation page provides some useful pointers: + * https://firefox-source-docs.mozilla.org/services/settings/index.html#unit-tests + +* Refer to the RemoteSettings docs for more details about managing the JSONSchema for the ``"main/addons-manager-settings"`` + collection and how to test it interactively in a Firefox instance: + * https://remote-settings.readthedocs.io/en/latest/getting-started.html + * https://firefox-source-docs.mozilla.org/services/settings/index.html#create-new-remote-settings + * https://firefox-source-docs.mozilla.org/services/settings/index.html#remote-settings-dev-tools + +.. _JSON Schema: + +AMRemoteSettings - JSON Schema +============================== + +The entries part of the ``"addons-manager-settings"`` collection are validated using a JSON Schema structured as follows: + +* The mandatory ``"id"`` property + * defaults to `"AddonManagerSettings"` (which enforces only one entry in the collection as the preferred use case) + * **should NOT be changed unless there is a specific need to create separate collection entries which target or exclude specific Firefox versions.** + * when changed and multiple entries are created in this collection, it is advisable to: + + * set the id to a short string value that make easier to understand the purpose of the additional entry in the collection + (eg. `AddonManagerSettings-fx98-99` for an entry created that targets Firefox 98 and 99) + * make sure only one applied to each targeted Firefox version ranges, or at least that each entry is controlling a different settings group + +* Each supported group of controlled settings is described by its own property (e.g. ``"installTriggerDeprecation"``) + + * JSON Schema for each group of settings is defined in an entry of the ``"definitions"`` property. + + * Each group of settings is contained it its own entry in ``"properties"``, named as the entry added to the ``"definitions"``) + and referencing (using ``"$ref"``) the related definition + +.. literalinclude :: ./AMRemoteSettings-JSONSchema.json + :language: json + +UI Schema +--------- + +In addition to the JSON Schema, a separate json called ``"UI schema"`` is associated to the ``"addons-manager-settings"`` collection, +and it can be used to customize the form auto-generated based on the JSONSchema data. + +.. note:: + Extending this schema is only needed if it can help to make the RemoteSettings collection easier to manage + and less error prone. + +.. literalinclude :: ./AMRemoteSettings-UISchema.json + :language: json |