koa_pm2_prometheus.js

var http = require('http');
var Koa = require('koa');
var Router = require('koa-router');

var app = new Koa();
var router = new Router();

const instanceId = parseInt(process.env.NODE_APP_INSTANCE || 0);
const client = require('prom-client');
client.collectDefaultMetrics();
client.register.setDefaultLabels({ instanceId: instanceId });

const appRequestSummary = new client.Summary({
  name: 'app_request',
  help: 'app_request',
  labelNames: ['method', 'name', 'type'],
  percentiles: [0.5, 0.75, 0.90, 0.95, 0.99, 1.0]
});

app.use(async (ctx, next) => {
  const start = Date.now();
  await next().then(data => {
    const ms = Date.now() - start;
    const routeName = ctx._matchedRouteName || 'unknown';
    appRequestSummary.labels(ctx.method, routeName, 'success').observe(ms);
  }).catch(err => {
    const ms = Date.now() - start;
    const routeName = ctx._matchedRouteName || 'unknown';
    appRequestSummary.labels(ctx.method, routeName, 'failure').observe(ms);
    throw err;
  });
});

router.get('index', '/', (ctx, next) => {
  ctx.body = 'Hello Koa';
});
router.get('fail', '/fail', (ctx, next) => {
  throw new Error("errorrrrrr");
});
// router.get('metrics', '/metrics', (ctx, next) => {
//   ctx.set('Content-Type', client.register.contentType);
//   ctx.body = client.register.metrics();
// });

app
    .use(router.routes())
    .use(router.allowedMethods());

const metricsPort = 9010 + instanceId;
console.log("start server: 3000, metrics server: " + metricsPort);

http.createServer((req, res) => {
  res.setHeader('Content-Type', client.register.contentType);
  res.write(client.register.metrics());
  res.end();
}).listen(metricsPort);
app.listen(3000);

# HELP app_request app_request
# TYPE app_request summary
app_request{instanceId="0",quantile="0.5",method="GET",name="index",type="success"} 1
app_request{instanceId="0",quantile="0.75",method="GET",name="index",type="success"} 2
app_request{instanceId="0",quantile="0.9",method="GET",name="index",type="success"} 2
app_request{instanceId="0",quantile="0.95",method="GET",name="index",type="success"} 2
app_request{instanceId="0",quantile="0.99",method="GET",name="index",type="success"} 2
app_request{instanceId="0",quantile="1",method="GET",name="index",type="success"} 2
app_request_sum{instanceId="0",method="GET",name="index",type="success"} 2
app_request_count{instanceId="0",method="GET",name="index",type="success"} 2
app_request{instanceId="0",quantile="0.5",method="GET",name="fail",type="failure"} 0.5
app_request{instanceId="0",quantile="0.75",method="GET",name="fail",type="failure"} 1
app_request{instanceId="0",quantile="0.9",method="GET",name="fail",type="failure"} 1
app_request{instanceId="0",quantile="0.95",method="GET",name="fail",type="failure"} 1
app_request{instanceId="0",quantile="0.99",method="GET",name="fail",type="failure"} 1
app_request{instanceId="0",quantile="1",method="GET",name="fail",type="failure"} 1
app_request_sum{instanceId="0",method="GET",name="fail",type="failure"} 1
app_request_count{instanceId="0",method="GET",name="fail",type="failure"} 2