feat: support useFactory

Closes #1776 Signed-off-by: Will Soto <willsoto@users.noreply.github.com>
willsoto · Aug 12, 2023 · b4608da · b4608da
1 parent 009891c
commit b4608da
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Showing 4 changed files with 91 additions and 37 deletions.
diff --git a/src/constants.ts b/src/constants.ts
@@ -4,3 +4,8 @@
  * @internal
  */
 export const PROMETHEUS_OPTIONS = Symbol("PROMETHEUS_OPTIONS");
+
+/**
+ * @internal
+ */
+export const PROM_CLIENT = Symbol("PROM_CLIENT");
diff --git a/src/interfaces.ts b/src/interfaces.ts
@@ -96,10 +96,7 @@ export interface PrometheusAsyncOptions
 
   /** {@inheritDoc PrometheusOptions.controller} */
   controller?: PrometheusOptions["controller"];
-  /**
-   * Not currently supported since there doesn't seem to be a way to get
-   * the result of the function during configuration.
-   */
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  // useFactory?(...args: any[]): Promise<PrometheusOptions> | PrometheusOptions;
+  useFactory?(
+    ...args: unknown[]
+  ): Promise<PrometheusOptions> | PrometheusOptions;
 }
diff --git a/src/module.ts b/src/module.ts
@@ -5,7 +5,7 @@ import {
   Provider,
 } from "@nestjs/common";
 import * as promClient from "prom-client";
-import { PROMETHEUS_OPTIONS } from "./constants";
+import { PROMETHEUS_OPTIONS, PROM_CLIENT } from "./constants";
 import { PrometheusController } from "./controller";
 import {
   PrometheusAsyncOptions,
@@ -55,15 +55,28 @@ export class PrometheusModule {
       module: PrometheusModule,
       controllers: [controller],
       imports: options.imports,
-      providers: providers,
-      exports: providers,
+      providers: [
+        ...providers,
+        {
+          provide: PROM_CLIENT,
+          inject: [PROMETHEUS_OPTIONS],
+          useFactory(userOptions: PrometheusOptions) {
+            const opts = PrometheusModule.makeDefaultOptions(userOptions);
+
+            PrometheusModule.configureServer(opts);
+
+            return promClient;
+          },
+        },
+      ],
+      exports: [...providers],
     };
   }
 
   public static createAsyncProviders(
     options: PrometheusAsyncOptions,
   ): Provider[] {
-    if (options.useExisting) {
+    if (options.useExisting || options.useFactory) {
       return [
         this.createAsyncOptionsProvider(options),
         PrometheusModule.createPushgatewayProvider(),
@@ -87,17 +100,14 @@ export class PrometheusModule {
   public static createAsyncOptionsProvider(
     options: PrometheusAsyncOptions,
   ): Provider {
-    /**
-     * Not currently supported since there doesn't seem to be a way to get
-     * the result of the function during configuration.
-     */
-    // if (options.useFactory) {
-    //   return {
-    //     provide: PROMETHEUS_OPTIONS,
-    //     useFactory: options.useFactory,
-    //     inject: options.inject || [],
-    //   };
-    // }
+    if (options.useFactory) {
+      return {
+        provide: PROMETHEUS_OPTIONS,
+        // eslint-disable-next-line @typescript-eslint/unbound-method
+        useFactory: options.useFactory,
+        inject: options.inject || [],
+      };
+    }
 
     const inject = options.useClass || options.useExisting;
 
@@ -112,12 +122,7 @@ export class PrometheusModule {
       async useFactory(
         optionsFactory: PrometheusOptionsFactory,
       ): Promise<PrometheusOptions> {
-        const userOptions = await optionsFactory.createPrometheusOptions();
-        const opts = PrometheusModule.makeDefaultOptions(userOptions);
-
-        PrometheusModule.configureServer(opts);
-
-        return opts;
+        return optionsFactory.createPrometheusOptions();
       },
       inject: [inject],
     };

diff --git a/test/module.spec.ts b/test/module.spec.ts
@@ -1,7 +1,12 @@
 import { Injectable, Module } from "@nestjs/common";
+import { TestingModule } from "@nestjs/testing";
 import { expect } from "chai";
-import { register } from "prom-client";
-import { PrometheusModule, PrometheusOptionsFactory } from "../src";
+import { Pushgateway, register } from "prom-client";
+import {
+  PrometheusModule,
+  PrometheusOptions,
+  PrometheusOptionsFactory,
+} from "../src";
 import {
   Agent,
   App,
@@ -12,12 +17,18 @@ import {
 describe("PrometheusModule", function () {
   let agent: Agent;
   let app: App;
+  let testingModule: TestingModule;
 
   afterEach(async function () {
+    register.clear();
+
     if (app) {
-      register.clear();
       await app.close();
     }
+
+    if (testingModule) {
+      await testingModule.close();
+    }
   });
 
   describe("#register", function () {
@@ -97,11 +108,6 @@ describe("PrometheusModule", function () {
         const response = await agent.get("/metrics");
 
         expect(response).to.have.property("status").to.eql(200);
-      });
-
-      it("collects default metrics", async function () {
-        const response = await agent.get("/metrics");
-
         expect(response)
           .to.have.property("text")
           .to.contain("process_cpu_user_seconds_total");
@@ -120,15 +126,56 @@ describe("PrometheusModule", function () {
         const response = await agent.get("/metrics");
 
         expect(response).to.have.property("status").to.eql(200);
+        expect(response)
+          .to.have.property("text")
+          .to.contain("process_cpu_user_seconds_total");
+      });
+    });
+
+    describe("useFactory", function () {
+      @Injectable()
+      class MyConfigService {
+        options(): PrometheusOptions {
+          return {
+            path: "/my/custom/path/metrics",
+            pushgateway: {
+              url: "http://127.0.0.1:9091",
+            },
+          };
+        }
+      }
+
+      @Module({
+        providers: [MyConfigService],
+        exports: [MyConfigService],
+      })
+      class MyConfigModule {}
+
+      beforeEach(async function () {
+        ({ agent, app, testingModule } = await createAsyncPrometheusModule({
+          imports: [MyConfigModule],
+          inject: [MyConfigService],
+          useFactory(config: MyConfigService) {
+            return config.options();
+          },
+        }));
       });
 
-      it("collects default metrics", async function () {
-        const response = await agent.get("/metrics");
+      it("registers a custom endpoint", async function () {
+        const response = await agent.get("/my/custom/path/metrics");
 
+        expect(response).to.have.property("status").to.eql(200);
         expect(response)
           .to.have.property("text")
           .to.contain("process_cpu_user_seconds_total");
       });
+
+      it("should register the push gateway", function () {
+        const gateway = testingModule.get(Pushgateway);
+
+        expect(gateway).to.be.instanceOf(Pushgateway);
+        expect(gateway).to.have.property("gatewayUrl", "http://127.0.0.1:9091");
+      });
     });
   });