a metrics decorator to automate function metrics in operation/action model to monitor system and upstream services as well as business metrics

It has been consolidated into n-express-monitor, please use that instead unless you're curious about things under the hood or want to customise your own tool chain

• Install
• Usage
  • setup
  • decorate functions
• Gotcha
  • the Metrics
  • the Meta
• Licence

npm i @financial-times/n-auto-metrics --save

/* app.js */
import { metrics } from 'n-express'; // or any other source has the `next-metrics` instance
import { initAutoMetrics } from '@financial-times/n-auto-metrics';

initAutoMetrics(metrics); // do this before app.use() any enhanced middleware/controller

A top level execution is categorised as an Operation, this can be an express middleware or controller function. Any lower level execution is categorised as an Action, and a two-level model of operation-action is encouraged.

With different log level settings, it would log the start, success/failure status of the function execution, function names to scope the operation/action, description of the error and params you need to recreate the error.

import { compose, autoNext, metricsOperation } from '@financial-times/n-auto-metrics';

const operation = (req, res) => {
  //let the error to be thrown
};

export default compose(
  autoNext,
  metricsOperation,
)(operation);

import { metricsAction } from '@financial-times/n-auto-metrics';

const action = (params: Object, meta: Object) => {}; // the function signature needs to follow the convention

export default metricsAction(action);

const operation = ({ meta }, res, next) => {
  action(param, meta); // pass the meta object from req.meta to thread operation/action
  //...
};

want even less lines of code?

for business metrics:

operation.${operation}.segment.${segment}.state.start operation.${operation}.segment.${segment}.state.success operation.${operation}.segment.${segment}.state.failure.category.${e.category}.type.${e.type}

for system reliability:

operation.${operation}.action.${action}.state.start operation.${operation}.action.${action}.state.success operation.${operation}.action.${action}.state.failure.category.${e.category}.type.${e.type} operation.${operation}.action.${action}.state.failure.category.${e.category}.status.${e.status}

for upstream service reliability:

service.${service}.action.${action}.state.start service.${service}.action.${action}.state.success service.${service}.action.${action}.state.failure.category.${e.category}.type.${e.type} service.${service}.action.${action}.state.failure.category.${e.category}.status.${e.status}

check the common meta used by n-auto-logger

meta.segment would be picked up in the metrics to help measure business metrics with user segment breakdown.

MIT