MongoDB to Grafana

Visualize data from MongoDB in Grafana.

This project is based on simple-json-datasource and mongodb-grafana which both seems to be discontinued at the moment.

We are creating a backend that implements 4 endpoints that is necessary to implement custom grafana datasource:

• / Used for test the connection with the datasource
• /search Used by the query tab in panels
• /query Return metrics based on input
• /annontations Return annotations

Inside the server folder there's a express server that exposes these endpoints and make the proxy to the mongodb.

The src folder contains some html partials, css and images that will be used to create the configuration page of the custom datasource in the grafana project. The gulp build task will use these files to create the final dist folder. The plugin.json is mandatory for the plugin, grafana will scan for this file inside the directory. I'm following the schema recommended by the grafana documentation here. The datasource.js should contain 4 funcions:

query(options);
testDatasource();
annotationQuery(options);
metricFindQuery(options);

The API is expecting values from the query with the following fields: name, value and ts. To accomplish that we are using the Mongo aggregation pipeline.

Prerequisites

• Grafana 6.x.x
• Node 10.x

Installation

1. Run the server with npm run server or node server/mongo-proxy.js, its defaults to port 3000.
2. Clone the project in the /usr/local/var/lib/grafana/plugins folder
3. Build the plugin front end with npm run build or npx gulp
4. Make sure the dist folder was created
5. Set the GF_PLUGIN_ALLOW_LOADING_UNSIGNED_PLUGINS env var to grafana-datasource-mongodb or add allow_loading_unsigned_plugins = grafana-datasource-mongodb to your grafana.ini file inside the [plugins] section
6. Restart the Grafana server. If installed via Homebrew, this can be done with brew services restart grafana

Usage

Query Editor

• Only aggregate are supported.
• You can only run one query.
• $from and $to are expanded by the plugin as BSON dates based on the range defined in the UI.

Visualizing time series data

The plugin needs to know which field to use as the time, you can simply project the field with a name alias of "ts". The field data type must be a date.

Example:

db.measurement.aggregate([
  {
    "$match": {
     "timeStamp": { "$gte": "$from", "$lte": "$to" }
    }
  }, {
    "$sort": {
      "timeStamp": -1
    }
  }, {
    "$unwind": "$values"
  }, {
    "$match": {
      "values.field": "CO"
    }
  }, {
    "$project": {
      "_id": 0,
      "name": "$box",
      "value": "$values.value",
      "ts": "$timeStamp"
    }
  }
])

Todo:

• [] Rewrite the express server
• Use gulp instead of grunt to run the tasks