Logging

Logging is the practice of emitting log messages that describe what is happening in the system, or “events” in short. Log events can have varying degrees of severity, such as debug, info, warning, error or even critical. By default, Open Notificaties emits logs with level info and higher.

A collection of log events with a correlation ID (like a request or trace ID) allow one to reconstruct the chain of events that took place which lead to a particular outcome.

Open Notificaties emits structured logs in JSON format (unless explicitly configured otherwise), which should make log aggregation and analysis easier.

We try to keep a consistent log message structure, where the following keys are (usually) present:

source: The component in the application stack that produced the log entry. Typical values are uwsgi and app.
level: The severity level of the log message. One of debug, info, warning, error or critical.
timestamp: The moment when the log entry was produced, a string in ISO-8601 format. Most of the logs have microsecond precision, but some of them are limited to second precision.
event: The event that occurred, e.g. request_started or spawned worker (PID 123). This gives the semantic meaning to the log entry.

Other keys that frequently occur are:

request_id: Present for application logs emitted during an HTTP request, makes it possible to correlate multiple log entries for a single request. Not available in logs emitted by background tasks or logs emitted before/after the Open Notificaties app.

Tip

Certain log aggregation solutions require you to configure “labels” to extract for efficient querying. You can use the above summary of log context keys to configure this according to your needs.

Note

We can not 100% guarantee that every log message will always be JSON due to limitations in third party software/packages that we use. Most (if not all) log aggregation technologies support handling both structured and unstructured logs.

Logging

Format

Open Notificaties emits structured logs (using structlog). A log line can be formatted like this:

{
    "event":"notification_received",
    "channel_name":"zaken",
    "resource":"zaak",
    "user_id":null,
    "resource_url":"http://openzaak.local/zaken/api/v1/zaken/1234",
    "additional_attributes":{
        "bronorganisatie":"000000000",
        "zaaktype":"http://openzaak.local/catalogi/api/v1/zaaktypen/1234",
        "zaaktype.catalogus":"http://openzaak.local/catalogi/api/v1/catalogussen/1234",
        "vertrouwelijkheidaanduiding":"openbaar"
    },
    "action":"create",
    "request_id":"5aa21b5c-d113-4dfa-a3c1-164ce7f325c8",
    "main_object_url":"http://openzaak.local/zaken/api/v1/zaken/1234",
    "creation_date":"2025-05-23T12:18:25.162276Z",
    "timestamp":"2025-05-23T12:18:25.162276Z",
    "logger":"nrc.api.serializers",
    "level":"info"
}

Each log line will contain an event type, a timestamp and a level. Dependent on your configured LOG_LEVEL (see Environment configuration reference for more information), only log lines with of that level or higher will be emitted.

Open Notificaties log events

Below is the list of logging event types that Open Notificaties can emit. In addition to the mentioned context variables, these events will also have the request bound metadata described in the django-structlog documentation.

API

deprecated_endpoint_called: a deprecated endpoint was called. Additional context: endpoint.
notification_received: a notification was received via the /notificaties endpoint. Additional context:
- channel_name
- resource
- resource_url
- main_object_url
- creation_date
- action
- additional_attributes
notification_successful: a notification was successfully forwarded to a subscribed callback URL. Additional context:
- channel_name
- resource
- resource_url
- main_object_url
- creation_date
- action
- additional_attributes
- subscription_pk
- notification_id
- subscription_callback
- notification_attempt_count the amount of times this task has been started for this notification
- task_attempt_count: the number of times this specific task has been attempted
notification_failed: a non success status code was returned while sending the notification to a subscribed callback URL. Additional context:
- channel_name
- resource
- resource_url
- main_object_url
- creation_date
- action
- additional_attributes
- subscription_pk
- notification_id
- subscription_callback
- http_status_code
- notification_attempt_count the amount of times this task has been started for this notification
- task_attempt_count: the number of times this specific task has been attempted
notification_error: an error occurred while trying to send the notification to a subscribed callback URL. Additional context:
- channel_name
- resource
- resource_url
- main_object_url
- creation_date
- action
- additional_attributes
- subscription_pk
- notification_id
- subscription_callback
- exc_info
- notification_attempt_count the amount of times this task has been started for this notification
- task_attempt_count: the number of times this specific task has been attempted
subscription_does_not_exist: could not retrieve an Abonnement for this pk and can therefore not deliver a message to this subscriber. Additional context:
- channel_name
- resource
- resource_url
- main_object_url
- creation_date
- action
- additional_attributes
- subscription_pk
- notification_id
scheduled_notification_does_not_exist: could not retrieve a ScheduledNotification for the specified primary key and can therefore not deliver its message.
no_notification_source: notification did not have a source and cannot be transformed into a cloudevent. Additional context:
- channel_name
- resource
- resource_url
- action
cloudevent_received: a cloudevent was received via the /cloudevents endpoint. Additional context:
- id
- source
- type
- subject
cloudevent_successful: a cloudevent was successfully forwarded to a subscribed callback URL. Additional context:
- id
- source
- type
- subject
- subscription_pk
- subscription_callback
- cloudevent_attempt_count the amount of times this task has been started for this cloudevent
- task_attempt_count: the number of times this specific task has been attempted
cloudevent_failed: a non success status code was returned while sending the cloudevent to a subscribed callback URL. Additional context:
- id
- source
- type
- subject
- subscription_pk
- subscription_callback
- http_status_code
- cloudevent_attempt_count the amount of times this task has been started for this cloudevent
- task_attempt_count: the number of times this specific task has been attempted
cloudevent_error: an error occurred while trying to send the cloudevent to a subscribed callback URL. Additional context:
- id
- source
- type
- subject
- subscription_pk
- subscription_callback
- exc_info
- cloudevent_attempt_count the amount of times this task has been started for this cloudevent
- task_attempt_count: the number of times this specific task has been attempted
executed_notifications: the execute_notification task has run
- waiting the amount of scheduled notifications that can be started
- stuck the amount of scheduled notifications that are in progress for NOTIFICATION_REQUESTS_TIMEOUT * 10
- in_progress the amount of scheduled notifications that are in progress
- started the amount of scheduled notifications that got started

Exceptions

Handled exceptions follow a standardized JSON format to ensure consistency and improve error tracking. Most fields are standard and include: title, code, status, event, source, user_id, request_id, timestamp, logger and level.

A new field invalid_params has been added to provide detailed information about which input parameters caused the error in API calls:

{
    "title": "'Je hebt geen toestemming om deze actie uit te voeren.'",
    "code": "permission_denied",
    "status": 403,
    "invalid_params": [
        {
            "name": "",
            "code": "permission_denied",
            "reason": "Je hebt geen toestemming om deze actie uit te voeren."
        }
    ],
    "event": "api.handled_exception",
    "request_id": "70fa58c1-2d89-4a57-a347-209bfb3cc846",
    "exception_id": "aabcf29e-d339-4983-8cef-061f740ed46b",
    "source": "app",
    "user_id": null,
    "timestamp": "2025-10-06T12:48:10.353372Z",
    "logger": "vng_api_common.exception_handling",
    "level": "error"
}

Uncaught exceptions that occur via the API are logged as api.uncaught_exception events and contain the traceback of the exception.

{
    "message": "division by zero",
    "event": "api.uncaught_exception",
    "request_id": "455f4e5e-cf96-48f5-a280-0dbbc3b6d38c",
    "source": "app",
    "user_id": null,
    "timestamp": "2025-10-06T12:52:23.070282Z",
    "logger": "vng_api_common.views",
    "level": "error",
    "exception": "Traceback (most recent call last):\n  File \"/usr/local/lib/python3.12/site-packages/rest_framework/views.py\", line 506, in dispatch\n    response = handler(request, *args, **kwargs)\n               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/app/src/nrc/api/viewsets.py\", line 93, in list\n    1 / 0\n    ~~^~~\nZeroDivisionError: division by zero"
}

Setup configuration

subscription_created: successfully created an Abonnement (subscription). Additional context: subscription_uuid, subscription_pk.
subscription_updated: successfully updated an Abonnement (subscription). Additional context: subscription_uuid, subscription_pk.
channel_created: successfully created a Kanaal (channel). Additional context: channel_name, channel_pk.
channel_updated: successfully updated a Kanaal (channel). Additional context: channel_name, channel_pk.

Schema generation

unknown_openapi_action: when generating the API schema, an unknown action was encountered and therefore no error responses can be shown. Additional context: action.

Third party library events

For more information about log events emitted by third party libraries, refer to the documentation for that particular library