prometheus-net.Contrib.MongoDb 0.6.0

prometheus-net.Contrib.MongoDb

Overview

prometheus-net.Contrib.MongoDb is a C# library that provides client-side Prometheus instrumentation for MongoDB operations (instrumenting MongoDB C# Driver)
It captures various metrics related to MongoDB commands, errors, and performance, and exports them to Prometheus for monitoring and alerting.

The Why

Why create another metrics library for MongoDB when there's already mongodb_exporter?
It is true that mongodb_exporter is a great tool for monitoring MongoDB, but it is a server-side tool that requires a separate process to run, possibly docker or other mode of deployment. On top of that, it "actively" gathers information by polling MongoDB while this exporter will do it "passively" by instrumenting the MongoDB C# Driver, without the need to run a separate process.

Note: This library is still in development and more metrics will be added

Metrics Exposed

Command Duration (mongodb_client_command_duration)

Histogram metric that measures the duration of MongoDB commands in seconds.

• Labels: command_type, status, target_collection, target_db

Open Cursors Count (mongodb_client_open_cursors_count)

Gauge metric that tracks the number of open cursors.

• Labels: target_collection, target_db

Open Cursors Duration (mongodb_client_open_cursors_duration)

Histogram metric that tracks the number of open cursors.

• Labels: target_collection, target_db

Open Cursor Document Count (mongodb_client_cursor_document_count)

Summary metric that measures the document count fetched by a cursor.

• Labels: target_collection, target_db

Command Errors (mongodb_client_command_errors_total)

Counter metric that counts the total number of MongoDB command errors.

• Labels: command_type, error_type, target_collection, target_db

Command Size (mongodb_command_response_size)

Histogram metric that measures the size of MongoDB commands in bytes.

• Labels: command_type, target_collection, target_db

Connection Creation Rate (mongodb_client_connection_creation_rate)

Counter metric that captures the rate at which new MongoDB connections are created.

• Labels: cluster_id, end_point

Connection Duration (mongodb_client_connection_duration)

Histogram metric that measures the time it takes to close a MongoDB connection, in seconds.

• Labels: cluster_id, end_point

Query Filter Size (mongodb_client_query_filter_size)

Histogram metric that tracks the size of MongoDB query filters.

• Labels: query_type, target_collection, target_db

Query Count (mongodb_client_query_count)

Counter metric that measures the number of "find" and "aggregate" MongoDB queries.

• Labels: query_type, target_collection, target_db

Note: This metric tries to capture the complexity of the filters being used in MongoDB queries. It recursively counts the number of clauses and items in the filters, which could be a useful metric for understanding query performance. Note that the performance in this case also depends on any indexes or their lack in the collection.

Usage Example

Here's a simple example to instrument your MongoDB client:

using MongoDB.Driver;

var settings = MongoClientSettings.FromConnectionString("your_connection_string_here");
settings = settings.InstrumentForPrometheus();

var client = new MongoClient(settings);

Installation

This library is available as a NuGet package. To install, run:

Install-Package prometheus-net.Contrib.MongoDb

Contributing

If you'd like to contribute, please fork the repository and use a feature branch. Pull requests are warmly welcome.

License

This project is licensed under the MIT License - see the LICENSE file for details.