adds prom client and initial set of metrics

package.json

@@ -39,6 +39,7 @@
     "ioredis": "^5.3.2",
     "pino": "^8.15.3",
     "pino-pretty": "^10.2.0",
+    "prom-client": "^15.1.0",
     "stellar-sdk": "11.1.0",
     "yargs": "^17.7.2"
   },

src/helper/test-helper.ts

@@ -1,6 +1,7 @@
 import { Client, fetchExchange } from "@urql/core";
 import pino from "pino";
 import { nativeToScVal } from "stellar-sdk";
+import Prometheus from "prom-client";
 
 import { mutation, query } from "../service/mercury/queries";
 import { MercuryClient } from "../service/mercury";
@@ -254,12 +255,15 @@ jest.spyOn(client, "mutation").mockImplementation((_mutation: any): any => {
   }
 });
 
+const register = new Prometheus.Registry();
+
 const mockMercuryClient = new MercuryClient(
   "http://example.com/graphql",
   mercurySession,
   client,
   renewClient,
-  testLogger
+  testLogger,
+  register
 );
 
 jest
@@ -274,7 +278,7 @@ jest
     }
   );
 async function getDevServer() {
-  const server = initApiServer(mockMercuryClient, testLogger);
+  const server = initApiServer(mockMercuryClient, testLogger, register);
   await server.listen();
   return server;
 }

src/index.ts

@@ -3,6 +3,7 @@ import { expand } from "dotenv-expand";
 import yargs from "yargs";
 import { Client, fetchExchange } from "@urql/core";
 import Redis from "ioredis";
+import Prometheus from "prom-client";
 
 import { logger } from "./logger";
 import { buildConfig } from "./config";
@@ -37,6 +38,12 @@ async function main() {
   const env = argv.env || "development";
   const port = argv.port || 3002;
 
+  const register = new Prometheus.Registry();
+  register.setDefaultLabels({
+    app: "freighter-backend",
+  });
+  Prometheus.collectDefaultMetrics({ register });
+
   const client = new Client({
     url: conf.mercuryGraphQL,
     exchanges: [fetchExchange],
@@ -82,9 +89,10 @@ async function main() {
     client,
     renewClient,
     logger,
+    register,
     redis
   );
-  const server = initApiServer(mercuryClient, logger, redis);
+  const server = initApiServer(mercuryClient, logger, register, redis);
 
   try {
     await server.listen({ port, host: "0.0.0.0" });

src/route/index.ts

@@ -3,6 +3,7 @@ import helmet from "@fastify/helmet";
 import rateLimiter from "@fastify/rate-limit";
 import { Logger } from "pino";
 import { Redis } from "ioredis";
+import Prometheus from "prom-client";
 
 import { MercuryClient } from "../service/mercury";
 import { ajv } from "./validators";
@@ -30,6 +31,7 @@ const API_VERSION = "v1";
 export function initApiServer(
   mercuryClient: MercuryClient,
   logger: Logger,
+  register: Prometheus.Registry,
   redis?: Redis
 ) {
   const server = Fastify({
@@ -55,6 +57,15 @@ export function initApiServer(
         },
       });
 
+      instance.route({
+        method: "GET",
+        url: "/metrics",
+        handler: async (_request, reply) => {
+          reply.header("Content-Type", register.contentType);
+          register.metrics().then((data) => reply.code(200).send(data));
+        },
+      });
+
       instance.route({
         method: "GET",
         url: "/account-history/:pubKey",

src/service/mercury/index.ts

@@ -4,6 +4,7 @@ import { Logger } from "pino";
 import { Address, Horizon, xdr } from "stellar-sdk";
 import { Redis } from "ioredis";
 import BigNumber from "bignumber.js";
+import Prometheus from "prom-client";
 
 import { mutation, query } from "./queries";
 import {
@@ -76,13 +77,16 @@ export class MercuryClient {
   accountSubUrl: string;
   redisClient?: Redis;
   logger: Logger;
+  mercuryErrorCounter: Prometheus.Counter<"endpoint">;
+  rpcErrorCounter: Prometheus.Counter<"rpc">;
 
   constructor(
     mercuryUrl: string,
     mercurySession: MercurySession,
     urqlClient: Client,
     renewClient: Client,
     logger: Logger,
+    register: Prometheus.Registry,
     redisClient?: Redis
   ) {
     this.mercuryUrl = mercuryUrl;
@@ -94,6 +98,19 @@ export class MercuryClient {
     this.renewClient = renewClient;
     this.logger = logger;
     this.redisClient = redisClient;
+
+    this.mercuryErrorCounter = new Prometheus.Counter({
+      name: "freighter_backend_mercury_error_count",
+      help: "Count of errors returned from Mercury",
+      labelNames: ["endpoint"],
+    });
+
+    this.rpcErrorCounter = new Prometheus.Counter({
+      name: "freighter_backend_rpc_error_count",
+      help: "Count of errors returned from Horizon or Soroban RPCs",
+      labelNames: ["rpc"],
+    });
+    register.registerMetric(this.mercuryErrorCounter);
   }
 
   tokenBalanceKey = (pubKey: string) => {
@@ -406,6 +423,11 @@ export class MercuryClient {
     } catch (error) {
       this.logger.error(error);
       const _error = JSON.stringify(error);
+      this.rpcErrorCounter
+        .labels({
+          rpc: "Horizon",
+        })
+        .inc();
       return {
         data: null,
         error: _error,
@@ -453,6 +475,13 @@ export class MercuryClient {
 
       if (!response.error) {
         return response;
+      } else {
+        this.logger.error(response.error);
+        this.mercuryErrorCounter
+          .labels({
+            endpoint: "getAccountHistory",
+          })
+          .inc();
       }
     }
 
@@ -616,6 +645,13 @@ export class MercuryClient {
       // if Mercury returns an error, fallback to the RPCs
       if (!response.error) {
         return response;
+      } else {
+        this.logger.error(response.error);
+        this.mercuryErrorCounter
+          .labels({
+            endpoint: "getAccountBalance",
+          })
+          .inc();
       }
     }
 
@@ -636,6 +672,11 @@ export class MercuryClient {
       this.logger.error(
         `failed to fetch token classic balances from Horizon: ${pubKey}, ${network}`
       );
+      this.rpcErrorCounter
+        .labels({
+          rpc: "Horizon",
+        })
+        .inc();
       return {
         data: null,
         error,
@@ -654,6 +695,11 @@ export class MercuryClient {
       this.logger.error(
         `failed to fetch token token balances from Soroban RPC: ${pubKey}, ${network}`
       );
+      this.rpcErrorCounter
+        .labels({
+          rpc: "Soroban",
+        })
+        .inc();
       return {
         data: null,
         error,

yarn.lock

@@ -685,6 +685,11 @@
     "@jridgewell/resolve-uri" "^3.1.0"
     "@jridgewell/sourcemap-codec" "^1.4.14"
 
+"@opentelemetry/api@^1.4.0":
+  version "1.7.0"
+  resolved "https://registry.yarnpkg.com/@opentelemetry/api/-/api-1.7.0.tgz#b139c81999c23e3c8d3c0a7234480e945920fc40"
+  integrity sha512-AdY5wvN0P2vXBi3b29hxZgSFvdhdxPB9+f0B6s//P9Q8nibRWeA3cHm8UmLpio9ABigkVHJ5NMPk+Mz8VCCyrw==
+
 "@sinclair/typebox@^0.27.8":
   version "0.27.8"
   resolved "https://registry.yarnpkg.com/@sinclair/typebox/-/typebox-0.27.8.tgz#6667fac16c436b5434a387a34dedb013198f6e6e"
@@ -1258,6 +1263,11 @@ bignumber.js@^9.1.2:
   resolved "https://registry.yarnpkg.com/bignumber.js/-/bignumber.js-9.1.2.tgz#b7c4242259c008903b13707983b5f4bbd31eda0c"
   integrity sha512-2/mKyZH9K85bzOEfhXDBFZTGd1CTs+5IHpeFQo9luiBG7hghdC851Pj2WAhb6E3R6b9tZj/XKhbg4fum+Kepug==
 
+[email protected]:
+  version "1.0.2"
+  resolved "https://registry.yarnpkg.com/bintrees/-/bintrees-1.0.2.tgz#49f896d6e858a4a499df85c38fb399b9aff840f8"
+  integrity sha512-VOMgTMwjAaUG580SXn3LacVgjurrbMme7ZZNYGSSV7mmtY6QQRh0Eg3pwIcntQ77DErK1L0NxkbetjcoXzVwKw==
+
 brace-expansion@^1.1.7:
   version "1.1.11"
   resolved "https://registry.yarnpkg.com/brace-expansion/-/brace-expansion-1.1.11.tgz#3c7fcbf529d87226f3d2f52b966ff5271eb441dd"
@@ -3090,6 +3100,14 @@ process@^0.11.10:
   resolved "https://registry.yarnpkg.com/process/-/process-0.11.10.tgz#7332300e840161bda3e69a1d1d91a7d4bc16f182"
   integrity sha512-cdGef/drWFoydD1JsMzuFf8100nZl+GT+yacc2bEced5f9Rjk4z+WtFUTBu9PhOi9j/jfmBPu0mMEY4wIdAF8A==
 
+prom-client@^15.1.0:
+  version "15.1.0"
+  resolved "https://registry.yarnpkg.com/prom-client/-/prom-client-15.1.0.tgz#816a4a2128da169d0471093baeccc6d2f17a4613"
+  integrity sha512-cCD7jLTqyPdjEPBo/Xk4Iu8jxjuZgZJ3e/oET3L+ZwOuap/7Cw3dH/TJSsZKs1TQLZ2IHpIlRAKw82ef06kmMw==
+  dependencies:
+    "@opentelemetry/api" "^1.4.0"
+    tdigest "^0.1.1"
+
 prompts@^2.0.1:
   version "2.4.2"
   resolved "https://registry.yarnpkg.com/prompts/-/prompts-2.4.2.tgz#7b57e73b3a48029ad10ebd44f74b01722a4cb069"
@@ -3537,6 +3555,13 @@ tapable@^2.1.1, tapable@^2.2.0:
   resolved "https://registry.yarnpkg.com/tapable/-/tapable-2.2.1.tgz#1967a73ef4060a82f12ab96af86d52fdb76eeca0"
   integrity sha512-GNzQvQTOIP6RyTfE2Qxb8ZVlNmw0n88vp1szwWRimP02mnTsx3Wtn5qRdqY9w2XduFNUgvOwhNnQsjwCp+kqaQ==
 
+tdigest@^0.1.1:
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/tdigest/-/tdigest-0.1.2.tgz#96c64bac4ff10746b910b0e23b515794e12faced"
+  integrity sha512-+G0LLgjjo9BZX2MfdvPfH+MKLCrxlXSYec5DaPYP1fe6Iyhf0/fSmJ0bFiZ1F8BT6cGXl2LpltQptzjXKWEkKA==
+  dependencies:
+    bintrees "1.0.2"
+
 terser-webpack-plugin@^5.3.7:
   version "5.3.9"
   resolved "https://registry.yarnpkg.com/terser-webpack-plugin/-/terser-webpack-plugin-5.3.9.tgz#832536999c51b46d468067f9e37662a3b96adfe1"