Extending the App

Contributions and extensions are welcome. Please open an issue first to discuss the proposed change before submitting a PR.

Adding Custom Metrics

To add a new Prometheus metric:

1. Define the metric in nautobot_graphql_observability/metrics.py:

   from prometheus_client import Counter
   
   graphql_deprecated_fields_total = Counter(
       "graphql_deprecated_fields_total",
       "Total usage of deprecated GraphQL fields",
       ["type_name", "field_name"],
   )
   

2. Import and record it in the appropriate method of PrometheusMiddleware in nautobot_graphql_observability/middleware.py.

3. If the metric should be optional, add a new boolean setting to NautobotAppGraphqlObservabilityConfig.default_settings in __init__.py and gate the recording behind a config check in the middleware.

Adding New Labels to Existing Metrics

Adding labels to existing metrics is a breaking change for Prometheus (it creates a new time series). If you need additional labels:

1. Consider creating a new metric instead.
2. If modifying an existing metric, update the label list in metrics.py and all .labels() calls in middleware.py.
3. Update tests to include the new label values.

Customizing Histogram Buckets

The default histogram buckets are defined in metrics.py. To customize them for your deployment, you can fork the metric definitions. A future enhancement may allow bucket configuration via PLUGINS_CONFIG.

Extending the Logging Middleware

The GraphQLQueryLoggingMiddleware in nautobot_graphql_observability/logging_middleware.py can be extended to add custom fields to log entries. The middleware uses Python's standard logging module with the logger name nautobot_graphql_observability.graphql_query_log.

To add custom log fields, subclass GraphQLQueryLoggingMiddleware and override _log_query():

from nautobot_graphql_observability.logging_middleware import GraphQLQueryLoggingMiddleware

class CustomLoggingMiddleware(GraphQLQueryLoggingMiddleware):
    @staticmethod
    def _log_query(config, operation_type, operation_name, user, start_time, info, error=None):
        # Call parent to emit the standard log entry
        GraphQLQueryLoggingMiddleware._log_query(
            config, operation_type, operation_name, user, start_time, info, error
        )
        # Add custom logic here