A prometheus module for Nest.
BREAKING CHANGE
nestjs-prom v0.2.x has been moved to stable/0.2 branch.
To migrate from v0.2 to v1.x please see Migrate from 0.2.x to 1.x
$ npm install --save @digikare/nestjs-prom prom-clientImport PromModule into the root ApplicationModule
import { Module } from '@nestjs/common';
import { PromModule } from '@digikare/nestjs-prom';
@Module({
imports: [
PromModule.forRoot({
defaultLabels: {
app: 'my_app',
version: 'x.y.z',
}
}),
]
})
export class ApplicationModule {}Here the options available for PromModule.forRoot:
| Option | Type | Default | Description |
|---|---|---|---|
| defaultLabels | Object<string, string | number> | {} |
| metricPath | string | /metrics |
Path to use to service metrics |
| withDefaultsMetrics | boolean | true |
enable defaultMetrics provided by prom-client |
| withDefaultController | boolean | true |
add internal controller to expose /metrics endpoints |
| withHttpMiddleware | object | {} |
Tttp middleware options for http requests metrics |
| withHttpMiddleware.enable | boolean | false |
Enable the middleware for http requests |
| withHttpMiddleware.timeBuckets | number[] | [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 10] |
The time buckets wanted |
| withHttpMiddleware.pathNormalizationExtraMasks | RegEx[] | [] |
The regexp mask for normalization |
To track the http requests metrics, simply set withHttpMiddleware.enable = true
By default, this feature is disabled.
import { Module } from '@nestjs/common';
import { PromModule } from '@digikare/nestjs-prom';
@Module({
imports: [
PromModule.forRoot({
withHttpMiddleware: {
enable: true,
}
}),
]
})
export class ApplicationModule {}To setup a metric, the module provide multiple ways to get a metric.
By using PromService service with DI to get a metric.
@Injectable()
export class MyService {
private readonly _counter: CounterMetric;
private readonly _gauge: GaugeMetric,
private readonly _histogram: HistogramMetric,
private readonly _summary: SummaryMetric,
constructor(
private readonly promService: PromService,
) {
this._counter = this.promService.getCounter({ name: 'my_counter' });
}
doSomething() {
this._counter.inc(1);
}
reset() {
this._counter.reset();
}
}You have the following decorators:
@PromCounter()@PromGauge()@PromHistogram()@PromSummary()
Below how to use it
import { CounterMetric, PromCounter } from '@digikare/nest-prom';
@Controller()
export class AppController {
@Get('/home')
home(
@PromCounter('app_counter_1_inc') counter1: CounterMetric,
@PromCounter({ name: 'app_counter_2_inc', help: 'app_counter_2_help' }) counter2: CounterMetric,
) {
counter1.inc(1);
counter2.inc(2);
}
@Get('/home2')
home2(
@PromCounter({ name: 'app_counter_2_inc', help: 'app_counter_2_help' }) counter: CounterMetric,
) {
counter.inc(2);
}
}import { GaugeMetric, PromGauge } from '@digikare/nest-prom';
@Controller()
export class AppController {
@Get('/home')
home(
@PromGauge('app_gauge_1') gauge1: GaugeMetric,
) {
gauge1.inc(); // 1
gauge1.inc(5); // 6
gauge1.dec(); // 5
gauge1.dec(2); // 3
gauge1.set(10); // 10
}
}If you want to counthow many instance of a specific class has been created:
@PromInstanceCounter()
export class MyClass {
}Will generate a counter called: app_MyClass_instances_total
If you want to increment a counter on each call of a specific method:
@Injectable()
export class MyService {
@PromMethodCounter()
doMyStuff() {
}
}Will generate a counter called: app_MyService_doMyStuff_calls_total and auto increment on each call
You can use that to monitor an endpoint
@Controller()
export class AppController {
@Get()
@PromMethodCounter() // will generate `app_AppController_root_calls_total` counter
root() {
// do your stuff
}
@Get('/login')
@PromMethodCounter({ name: 'app_login_endpoint_counter' }) // set the counter name
login() {
// do your stuff
}
}The default metrics endpoint is /metrics this can be changed with the metricPath option
@Module({
imports: [
PromModule.forRoot({
defaultLabels: {
app: 'my_app',
},
metricPath: 'custom/uri',
}),
],
})
export class MyModuleNow your metrics can be found at /custom/uri.
PS: If you have a global prefix, the path will be
{globalPrefix}/metricsfor the moment.
| Option | Type | Default | Description |
|---|---|---|---|
| defaultLabels | Object<string, string | number> | {} |
| metricPath | string | /metrics |
Path to use to service metrics |
| withDefaultsMetrics | boolean | true |
enable defaultMetrics provided by prom-client |
| withDefaultController | boolean | true |
add internal controller to expose /metrics endpoints |
| withHttpMiddleware | object | {} |
To enable the http middleware for http metrics |
| withHttpMiddleware.enable | boolean | false |
Enable http middleware |
| withHttpMiddleware.timeBuckets | number[] | [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 10] |
The time buckets wanted |
| withHttpMiddleware.pathNormalizationExtraMasks | RegEx[] | [] |
The regexp mask for normalization |
@PromInstanceCounter()Class decorator, create and increment on each instance created@PromMethodCounter()Method decorator, create and increment each time the method is called@PromCounter()Param decorator, create/find counter metric@PromGauge()Param decorator, create/find gauge metric@PromHistogram()Param decorator, create/find histogram metric@PromSummary()Param decorator, create/find summary metric
I do not provide any auth/security for /metrics endpoints.
This is not the aim of this module, but depending of the auth strategy, you can
apply a middleware on /metrics to secure it.
MIT licensed
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