feat: add prefix to all injected metrics

src/interfaces.ts

@@ -26,6 +26,15 @@ export interface PrometheusDefaultMetrics {
  * @public
  */
 export interface PrometheusOptions {
+  /**
+   * Similar to `defaultMetrics.prefix`, this will be applied to each custom
+   * metric created using the various providers. Will suffix the given prefix
+   * with `_`.
+   *
+   * For example, given a metric name of "my_metric" and a prefix of "app"
+   * would create a metric name of `app_my_metric`
+   * */
+  customMetricPrefix?: string;
   /**
    * A custom controller to be used instead of the default one. Only needs to be
    * provided if you need to do any kind of customization on the route, eg Swagger.
@@ -72,7 +81,7 @@ export interface PrometheusOptions {
 }
 
 export type PrometheusOptionsWithDefaults = Required<
-  Omit<PrometheusOptions, "pushgateway">
+  Omit<PrometheusOptions, "pushgateway" | "customMetricPrefix">
 >;
 
 /**

src/metrics/counter.ts

@@ -1,5 +1,7 @@
 import { Provider } from "@nestjs/common";
 import * as client from "prom-client";
+import { PROMETHEUS_OPTIONS } from "../constants";
+import { PrometheusOptions } from "../interfaces";
 import { getOrCreateMetric, getToken } from "./utils";
 
 /**
@@ -10,8 +12,9 @@ export function makeCounterProvider(
 ): Provider {
   return {
     provide: getToken(options.name),
-    useFactory(): client.Metric<string> {
-      return getOrCreateMetric("Counter", options);
+    useFactory(config?: PrometheusOptions): client.Metric<string> {
+      return getOrCreateMetric("Counter", options, config);
     },
+    inject: [PROMETHEUS_OPTIONS],
   };
 }

src/metrics/gauge.ts

@@ -1,5 +1,7 @@
 import { Provider } from "@nestjs/common";
 import * as client from "prom-client";
+import { PROMETHEUS_OPTIONS } from "../constants";
+import { PrometheusOptions } from "../interfaces";
 import { getOrCreateMetric, getToken } from "./utils";
 
 /**
@@ -10,8 +12,9 @@ export function makeGaugeProvider(
 ): Provider {
   return {
     provide: getToken(options.name),
-    useFactory(): client.Metric<string> {
-      return getOrCreateMetric("Gauge", options);
+    useFactory(config?: PrometheusOptions): client.Metric<string> {
+      return getOrCreateMetric("Gauge", options, config);
     },
+    inject: [PROMETHEUS_OPTIONS],
   };
 }

src/metrics/histogram.ts

@@ -1,5 +1,7 @@
 import { Provider } from "@nestjs/common";
 import * as client from "prom-client";
+import { PROMETHEUS_OPTIONS } from "../constants";
+import { PrometheusOptions } from "../interfaces";
 import { getOrCreateMetric, getToken } from "./utils";
 
 /**
@@ -10,8 +12,9 @@ export function makeHistogramProvider(
 ): Provider {
   return {
     provide: getToken(options.name),
-    useFactory(): client.Metric<string> {
-      return getOrCreateMetric("Histogram", options);
+    useFactory(config?: PrometheusOptions): client.Metric<string> {
+      return getOrCreateMetric("Histogram", options, config);
     },
+    inject: [PROMETHEUS_OPTIONS],
   };
 }

src/metrics/summary.ts

@@ -1,5 +1,7 @@
 import { Provider } from "@nestjs/common";
 import * as client from "prom-client";
+import { PROMETHEUS_OPTIONS } from "../constants";
+import { PrometheusOptions } from "../interfaces";
 import { getOrCreateMetric, getToken } from "./utils";
 
 /**
@@ -10,8 +12,9 @@ export function makeSummaryProvider(
 ): Provider {
   return {
     provide: getToken(options.name),
-    useFactory(): client.Metric<string> {
-      return getOrCreateMetric("Summary", options);
+    useFactory(config?: PrometheusOptions): client.Metric<string> {
+      return getOrCreateMetric("Summary", options, config);
     },
+    inject: [PROMETHEUS_OPTIONS],
   };
 }

src/metrics/utils.ts

@@ -1,4 +1,5 @@
 import * as client from "prom-client";
+import { PrometheusOptions } from "../interfaces";
 
 /**
  * @internal
@@ -20,24 +21,31 @@ export type Options =
 export function getOrCreateMetric(
   type: Metrics,
   options: Options,
+  prometheusOptions?: PrometheusOptions,
 ): client.Metric<string> {
-  const existingMetric = client.register.getSingleMetric(options.name);
+  const opts: Options = {
+    ...options,
+    name: prometheusOptions?.customMetricPrefix
+      ? prometheusOptions.customMetricPrefix.concat("_", options.name)
+      : options.name,
+  };
 
+  const existingMetric = client.register.getSingleMetric(opts.name);
   if (existingMetric) {
     return existingMetric;
   }
 
   switch (type) {
     case "Gauge":
-      return new client.Gauge(options as client.GaugeConfiguration<string>);
+      return new client.Gauge(opts as client.GaugeConfiguration<string>);
     case "Counter":
-      return new client.Counter(options as client.CounterConfiguration<string>);
+      return new client.Counter(opts as client.CounterConfiguration<string>);
     case "Histogram":
       return new client.Histogram(
-        options as client.HistogramConfiguration<string>,
+        opts as client.HistogramConfiguration<string>,
       );
     case "Summary":
-      return new client.Summary(options as client.SummaryConfiguration<string>);
+      return new client.Summary(opts as client.SummaryConfiguration<string>);
     default:
       // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
       throw new Error(`Unknown type: ${type}`);

src/module.ts

@@ -26,7 +26,12 @@ export class PrometheusModule {
 
     PrometheusModule.configureServer(opts);
 
-    const providers: Provider[] = [];
+    const providers: Provider[] = [
+      {
+        provide: PROMETHEUS_OPTIONS,
+        useValue: options,
+      },
+    ];
     if (options?.pushgateway !== undefined) {
       const { url, options: gatewayOptions, registry } = options.pushgateway;
       providers.push({

test/metrics/counter.spec.ts

@@ -2,7 +2,12 @@ import { Injectable } from "@nestjs/common";
 import { Test, TestingModule } from "@nestjs/testing";
 import { expect } from "chai";
 import * as client from "prom-client";
-import { Counter, register } from "prom-client";
+import {
+  Counter,
+  MetricObjectWithValues,
+  MetricValue,
+  register,
+} from "prom-client";
 import {
   InjectMetric,
   PrometheusModule,
@@ -56,4 +61,10 @@ describe("Counter", function () {
 
     expect(service.counter).to.be.instanceOf(Counter);
   });
+
+  it(`name has no prefix besides "controller_counter"`, async function () {
+    const metricValues: MetricObjectWithValues<MetricValue<string>> =
+      await metric.get();
+    expect(metricValues.name).to.equal("controller_counter");
+  });
 });

test/metrics/gauge.spec.ts

@@ -1,7 +1,9 @@
 import { Test, TestingModule } from "@nestjs/testing";
 import { expect } from "chai";
 import * as client from "prom-client";
+import { MetricObjectWithValues, MetricValue } from "prom-client";
 import { getToken, makeGaugeProvider } from "../../src";
+import { PROMETHEUS_OPTIONS } from "../../src/constants";
 
 describe("Gauge", function () {
   let testingModule: TestingModule;
@@ -10,6 +12,12 @@ describe("Gauge", function () {
   beforeEach(async function () {
     testingModule = await Test.createTestingModule({
       providers: [
+        {
+          provide: PROMETHEUS_OPTIONS,
+          useValue: {
+            customMetricPrefix: "app",
+          },
+        },
         makeGaugeProvider({
           name: "controller_gauge",
           help: "controller_gauge_help",
@@ -35,4 +43,11 @@ describe("Gauge", function () {
   it("has the appropriate methods (dec)", function () {
     expect(metric.dec).to.be.a("function");
   });
+
+  it("name has the prefix of APP", async function () {
+    const metricValues: MetricObjectWithValues<MetricValue<string>> =
+      await metric.get();
+
+    expect(metricValues.name).to.eq("app_controller_gauge");
+  });
 });

test/metrics/histogram.spec.ts

@@ -1,7 +1,9 @@
 import { Test, TestingModule } from "@nestjs/testing";
 import { expect } from "chai";
 import * as client from "prom-client";
+import { MetricObjectWithValues, MetricValue } from "prom-client";
 import { getToken, makeHistogramProvider } from "../../src";
+import { PROMETHEUS_OPTIONS } from "../../src/constants";
 
 describe("Histogram", function () {
   let testingModule: TestingModule;
@@ -14,6 +16,12 @@ describe("Histogram", function () {
           name: "controller_histogram",
           help: "controller_histogram_help",
         }),
+        {
+          provide: PROMETHEUS_OPTIONS,
+          useValue: {
+            customMetricPrefix: "app",
+          },
+        },
       ],
     }).compile();
 
@@ -31,4 +39,11 @@ describe("Histogram", function () {
   it("has the appropriate methods (observe)", function () {
     expect(metric.observe).to.be.a("function");
   });
+
+  it("name has the prefix of APP", async function () {
+    const metricValues: MetricObjectWithValues<MetricValue<string>> =
+      await metric.get();
+
+    expect(metricValues.name).to.eq("app_controller_histogram");
+  });
 });

test/metrics/summary.spec.ts

@@ -1,7 +1,9 @@
 import { Test, TestingModule } from "@nestjs/testing";
 import { expect } from "chai";
 import * as client from "prom-client";
+import { MetricObjectWithValues, MetricValue } from "prom-client";
 import { getToken, makeSummaryProvider } from "../../src";
+import { PROMETHEUS_OPTIONS } from "../../src/constants";
 
 describe("Summary", function () {
   let testingModule: TestingModule;
@@ -14,6 +16,12 @@ describe("Summary", function () {
           name: "controller_summary",
           help: "controller_summary_help",
         }),
+        {
+          provide: PROMETHEUS_OPTIONS,
+          useValue: {
+            customMetricPrefix: "app",
+          },
+        },
       ],
     }).compile();
 
@@ -31,4 +39,11 @@ describe("Summary", function () {
   it("has the appropriate methods (observe)", function () {
     expect(metric.observe).to.be.a("function");
   });
+
+  it("name has the prefix of APP", async function () {
+    const metricValues: MetricObjectWithValues<MetricValue<string>> =
+      await metric.get();
+
+    expect(metricValues.name).to.eq("app_controller_summary");
+  });
 });