@financial-times/n-auto-metrics NPM

n-auto-metrics

an enhancer to auto record metrics of function calls in operation/action model with a single line of code

npm download node version

Quickstart

initialise metrics before using enhanced middleware

/* 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

enhance action function to auto metrics, use tagService to add service before metricsAction if you want to set metrics of one service namespace

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

// auto metrics function of its start, success/failure state
const result = metricsAction(someFunction)(args: Object, meta?: Object);

// auto metrics multiple functions wrapped in an object
const APIService = compose(
  tagService('some-service'),
  metricsAction
)({ 
  methodA, 
  methodB, 
  methodC 
});

more details on action function

// auto log success/failure express middleware/controller as an operation function 
// function name would be logged as `operation`, and available in meta
const operationFunction = (meta, req, res) => { /* try-catch-throw */ };
export default toMiddleware(metricsOperation(operationFunction));

// auto log multiple operation functions wrapped in an object as controller
const someController = toMiddlewares(metricsOperation({ operationFunctionA, operationFuncitonB }));

check use res.render
more details on operation function
more details on chain with other enhancers

Install

npm install @financial-times/n-auto-metrics

Gotcha

reserved fields

operation default to operationFunction.name
service default to undefined, can be specified in paramsOrArgs or meta(autoLogActions('service-name'))
action default to callFunction.name
category NError category would be recorded in metrics
type is used by convention to record custom error type names for monitoring and debugging
status in error object would be recorded for service action call failure
stack used in Error or NError to store the stack trace
result default to success/failure

metrics format

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