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nextcloud-docs/developer_manual/exapp_development/tech_details/InstallationFlow.rst
2024-12-06 11:49:15 -08:00

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.. _app_installation_flow:
App Installation Flow
=====================
Image Pulling (Docker)
----------------------
AppAPI will first try to pull the Docker image whose ``suffix`` is equal to the value of *computeDevice*.
The following values are available for ``computeDevice``: ``cpu``, ``cuda``, or ``rocm``.
The suffix will be added as follows:
.. code::
return $imageParams['image_src'] . '/' .
$imageParams['image_name'] . '-' . $daemonConfig['computeDevice']['id'] . ':' . $imageParams['image_tag'];
For ``cpu``, AppAPI will first try to get the image from ``ghcr.io/nextcloud/skeleton-cpu:latest``.
In case the image is not found, ``ghcr.io/nextcloud/skeleton:latest`` will be pulled.
If you as an application developer want to have a custom images for any of these values,
you can push the extended images to the registry in addition to the base one.
Heartbeat
---------
The first thing AppAPI does is deploy the application.
In the case of Docker, this means:
1. performing an image pull
2. creating container from the docker image
3. if the container supports `healthcheck` - AppAPI waits for the `healthy` status
4. waiting until the “/heartbeat” endpoint becomes available with a ``GET`` request
The application, in response to the "/heartbeat" request, should return: ``{"status": "ok"}``.
.. note:: The request to the ``/heartbeat`` endpoint is made without AppAPI authentication.
Init
----
.. note:: Starting from this point, all requests made by AppAPI contain :ref:`authentication headers <auth-headers>`.
After the application is ready, which is determined by the previous step,
AppAPI sends a ``POST`` request to the ``/init`` application endpoint.
*If the application does not need to carry out long initialization, it has an option to not implement "/init" endpoint, so
AppAPI will get 404 or 501 error on it's request, but you can consider that initialization to be done and this section can be skipped.*
In case you want to implement "/init" endpoint, your application should:
1. In "/init" handler: return a Response with empty JSON data on AppAPI call.
2. In background job: send an OCS request to ``PUT /ocs/v1.php/apps/app_api/ex-app/status`` with the progress value.
.. warning::
``PUT /ocs/v1.php/apps/app_api/apps/status/$APP_ID`` is deprecated and will be removed in the future.
Possible values for **progress** are integers from 1 to 100;
after receiving the value 100, the **application is considered initialized and ready to work**.
If, at the initialization stage, the application has a critical error due to which its further operation is impossible,
``"error": "some error"``
should be added to the ``OCS request`` for setting progress,
with a short explanation at what stage this error occurred.
Example of request payload with error::
{"progress": 67, "error": "connection error to huggingface."}
Enabled
-------
After receiving **progress: 100** (*or when the ExApp is not implementing the "/init" endpoint*), AppAPI enables the application.
To enable or disable the application, a PUT request is sent to the ``/enabled`` endpoint.
.. note:: Unlike using a payload, this request utilizes a query parameter named ``enabled`` to specify the desired state.
The ``enabled`` parameter accepts an integer value:
* `1` to enable the application
* `0` to disable the application
For example, to enable the application, the request would be::
PUT http://ex-app:2432/enabled?enabled=1
Similarly, to disable the application, the request would be::
PUT http://ex-app:2432/enabled?enabled=0
This approach ensures that the application's state can be easily toggled using a simple query parameter.
.. note:: The ``/enabled`` endpoint shares both **enabling** and **disabling**,
so the app should determine what is going on using the ``enabled`` input parameter of the request.
Inside the ``/enabled`` handler, the application should register all actions related to the Nextcloud, such as the UI and other stuff.
The response for this request should contain::
{"error": ""}
for success, and if some error occurs during **enabling**, it should be present and not be empty::
{"error": "i can't handle enabling"}
This is all the steps involved in the ExApp installation flow.