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docs: local event bus development
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MichaelRoytman committed Oct 4, 2023
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105 changes: 101 additions & 4 deletions README.rst
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Development Workflow
--------------------

One Time Setup
~~~~~~~~~~~~~~
Local Development Set Up
~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block::
# Clone the repository
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# Run edx-exams locally
python manage.py runserver localhost:18740 --settings=edx_exams.settings.local
Devstack Set Up
~~~~~~~~~~~~~~~
.. code-block::
# Clone the repository
git clone [email protected]:edx/edx-exams.git
cd edx-exams
Every time you develop something in this repo
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Start LMS in devstack from your local devstack directory
make dev.up.lms
# Return to the edx-exams repo directory and provision the edx-exams containers
bash provision-edx-exams.sh
You can use the make targets defined in the ``Makefile`` to interact with the running ``edx-exams`` Docker containers.

Development Workflow
~~~~~~~~~~~~~~~~~~~~
.. code-block::
# Activate the virtualenv
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# Open a PR and ask for review.
Event Bus Set Up
~~~~~~~~~~~~~~~~

The ``edx-exams`` service uses the Open edX event bus to publish events relating to the exam attempt lifecycle and
others important exam events. These Open edX events are emitted by the service and pushed onto the event bus. Downstream
services, like the LMS, receive these events and implement downstream effects of these events. For more details,
please see `Implementation of Event Driven Architecture for Exam Downstream Effects`_.

These focus of these instructions is on how to set up the Open edX event bus for use with ``edx-exams``. For more
documentation about the event bus in general, please see `How to start using the Event Bus`_.

Currently, the event bus is only supported in environments running Docker containers, like `devstack`_. This is because
the interactions between services on the event bus is implemented in the devstack networking layer.

In order to run the event bus locally, follow these steps. These steps assume that you both have `devstack`_ running and
that you are running the ``edx-exams`` Docker container, as described in the Devstack Set Up section. These steps
describe how to install and run the Kafka-based event bus.

1. In a ``requirements/private.txt`` file, add the following Python package. These requirements are necessary for the
Kafka-based event bus. They are not included as a part of the standard set of requirements because installation of
confluent_kafka poses issues for users of Tutor on M1 Macs, which includes many users in the Open edX community.
For more details, please see `Optional Import of Confluent Kafka`_.


.. code-block::
confluent_kafka[avro,schema-registry]
2. Install the application requirements to install ``confluent_kafka``.

.. code-block::
# Shell into the application Docker container
make app-shell
# Install requirements
make requirements
3. Follow the `manual testing`_ instructions to set up the Kafka-based Open edX event bus in the service that contains
the event handler(s) for your event(s) - for example, the LMS or Studio.

Producing Events
################

Events will be produced at key stages of the exam attempt lifecycle and other points in the special exam feature. If you
are using the local Kafka cluster, you will be able to see the topics and events there.

Consuming Events
################

In order to consume events off the event bus, you must run a management command that starts an infinite loop to read
from the event bus.

Shell into the application Docker container and run the following management command to start the loop. See the
`consume_events management command documentation`_ for a description of the arguments.

.. code-block::
python3 manage.py consume_events -t <topic-name> -g <group-id>
Here is an example of a command to consume events from the ``learning-exam-attempt-lifecycle`` topic in the LMS.

.. code-block::
python3 manage.py ls consume_events -t learning-exam-attempt-lifecycle -g dev-lms
When your event is successfully consumed, you should see logs like the following.

.. code-block::
2023-10-04 15:50:17,508 INFO 554 [edx_event_bus_kafka.internal.consumer] [user None] [ip None] consumer.py:513 - Message received from Kafka: topic=dev-learning-exam-attempt-lifecycle, partition=0, offset=7, message_id=b71c735c-62cd-11ee-9064-0242ac120012, key=b'\x00\x00\x00\x00\x010course-v1:edX+777+2023FW', event_timestamp_ms=1696434617498
2023-10-04 15:50:17,593 INFO 554 [edx_event_bus_kafka.internal.consumer] [user None] [ip None] consumer.py:393 - Message from Kafka processed successfully
.. _Implementation of Event Driven Architecture for Exam Downstream Effects: https://github.com/edx/edx-exams/blob/main/docs/decisions/0004-downstream-effect-events.rst
.. _How to start using the Event Bus: https://openedx.atlassian.net/wiki/spaces/AC/pages/3508699151/How+to+start+using+the+Event+Bus
.. _devstack: https://edx.readthedocs.io/projects/open-edx-devstack/en/latest/
.. _Optional Import of Confluent Kafka: https://github.com/openedx/event-bus-kafka/blob/main/docs/decisions/0005-optional-import-of-confluent-kafka.rst.
.. _manual testing: https://github.com/openedx/event-bus-kafka/blob/main/docs/how_tos/manual_testing.rst
.. _consume_events management command documentation: https://github.com/openedx/openedx-events/blob/7e6e92429485133bf16ae4494da71b5a2ac31b9e/openedx_events/management/commands/consume_events.py

Setting up an exam and proctoring tool
--------------------------------------

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4 changes: 3 additions & 1 deletion docker-compose.yml
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version: "2.1"
services:
db:
image: mysql:5.6
# Oracle-packaged version includes a `linux/arm64/v8` version, needed for
# machines with Apple Silicon CPUs (Mac M1, M2)
image: mysql:8.0.33-oracle
container_name: edx_exams.db
environment:
MYSQL_ROOT_PASSWORD: ""
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