.env

@@ -0,0 +1,6 @@
+PAIRS=BTC-USD,ETH-USD,XRP-USD,BTC-EUR,ETH-EUR,CNYUSD
+INTERVAL=5000
+THRESHOLD=0.05
+POSTGRES_USER=uphold
+POSTGRES_PASSWORD=uphold
+POSTGRES_DB=uphold_events

.env.example

@@ -1,6 +0,0 @@
-PAIRS=BTC-USD,CNYUSD
-INTERVAL=5000
-THRESHOLD=0.05
-POSTGRES_USER=uphold
-POSTGRES_PASSWORD=uphold
-POSTGRES_DB=uphold_db

.gitignore

@@ -1,3 +1,2 @@
 node_modules/
 package-lock.json
-.env

Containerfile

@@ -1,12 +1,12 @@
 FROM docker.io/node:20-alpine
 WORKDIR /app
 COPY package*.json ./
+# RUN npm ci --omit=dev
 RUN npm ci
 COPY src/ ./src/
 COPY index.js ./
 
-RUN addgroup -g 1001 uphold && adduser -S -G uphold -u 1001 uphold
-USER uphold
+RUN addgroup -g 1001 nodejs && adduser -S -G nodejs -u 1001 nodejs
+USER nodejs
 
-EXPOSE 3000
 ENTRYPOINT ["node", "index.js"]

README.md

@@ -1,158 +0,0 @@
-# Uphold currency rate bot for interview
-## Requirements
-
-- Node.js >= v20
-- Docker and Docker Compose (optionally, Podman and Podman compose)
-- PostgreSQL (if running outside of Docker)
-
-## Quick Start
-
-### 1. Install Dependencies
-
-```bash
-npm install
-```
-
-### 2. Run the Bot
-
-**With default parameters, no DB or API:**
-```bash
-node index.js
-```
-or 
-
-```bash
-npm start
-```
-
-**With custom parameters:**
-```bash
-node index.js --pairs BTC-USD,ETH-USD --interval 10000 --threshold 0.05
-```
-
-or 
-
-```bash
-npm start -- --pairs BTC-USD,ETH-USD --interval 10000 --threshold 0.01
-```
-
-**With environment file:**
-```bash
-node --env-file=.env.example index.js
-```
-
-### 3. Run with Docker/Podman Compose (includes DB and API)
-
-```bash
-cp .env.example .env
-````
-
-Edit .env with your settings:
-
-```
-POSTGRES_USER=uphold
-POSTGRES_PASSWORD=uphold
-POSTGRES_DB=uphold_db
-PAIRS=BTC-USD,ETH-USD
-INTERVAL=5000
-THRESHOLD=0.01
-```
-
-```
-# Start services
-docker compose up -d --build 
-
-```
-or 
-
-```
-podman compose up -d --build
-```
-
-# View logs
-
-```
-docker compose logs -f uphold_bot_1
-```
-
-or 
-
-```
-podman compose logs -f uphold_bot_1
-```
-
-## Configuration
-
-| Parameter | Flag | Environment | Default | Description |
-|-----------|------|-------------|---------|-------------|
-| Pairs | `-p, --pairs` | `PAIRS` | `BTC-USD` | Comma-separated currency pairs |
-| Interval | `-i, --interval` | `INTERVAL` | `5000` | Uphold API retrieval interval in milliseconds |
-| Threshold | `-t, --threshold` | `THRESHOLD` | `0.01` | Alert difference percentage |
-
-## Running Tests
-
-```bash
-npm test
-```
-
-## API
-### Endpoints
-
-**Health Check**
-```bash
-curl http://localhost:3000/health
-```
-
-**Statistics**
-```bash
-curl http://localhost:3000/stats
-```
-
-**Alerts**
-```bash
-# Get last 50 alerts (default)
-curl http://localhost:3000/alerts
-
-# Get last 100 alerts
-curl http://localhost:3000/alerts?limit=100
-```
-
-## Example Output
-
-```
-[18:44:51.898] INFO: Bot starting...
-[18:44:51.898] INFO: [WATCHING] BTC-USD | Every 5000ms | Threshold 0.01%
-[18:44:51.898] WARN: [DB] specificiation missing. Running in memor
-[18:44:52.167] INFO: [BTC-USD] Monitoring every 5000ms, +/-0.01%
-[18:44:52.367] INFO: [BTC-USD] Initial price: 90977.65
-[18:45:07.879] INFO: [ALERT] BTC-USD DOWN -0.0116%
-    pair: "BTC-USD"
-    direction: "DOWN"
-    change: "-0.0116%"
-    prev: "90977.648894"
-    curr: "90967.085674"
-```
-
-## Architecture
-- `index.js` - Entry point
-- `src/bot.js` - Bot logic
-- `src/api.js` - Uphold API client
-- `src/db.js` - DB logic
-- `src/logger.js` - Simple logging
-- `src/server.js` - API server for docker diagnosis
-- `src/stats.js` - Statistics tracking
-- `tests/bot.test.js` - Tests
-
-## Stopping the Bot
-
-Press `Ctrl+C` or send `SIGTERM` for graceful shutdown.
-
-With Docker:
-```bash
-docker compose down
-```
-or Podman
-```bash
-podman compose down
-podman volume rm uphold_pgdata
-```

compose.yml

@@ -1,21 +1,16 @@
 services:
   bot:
-    build:
-      context: .
-      dockerfile: Containerfile
-    ports:
-      - "3000:3000"
+    build: .
     depends_on:
       db:
         condition: service_healthy
     environment:
-      - PORT=3000
       - DATABASE_URL=postgres://${POSTGRES_USER}:${POSTGRES_PASSWORD}@db:5432/${POSTGRES_DB}
       - PAIRS=${PAIRS:-BTC-USD}
       - INTERVAL=${INTERVAL:-5000}
       - THRESHOLD=${THRESHOLD:-0.01}
     healthcheck:
-      test: ["CMD", "wget", "--no-verbose", "--tries=1", "http://localhost:3000/health"]
+      test: ["CMD", "node", "-e", "require('node:process').exit(require('fs').existsSync('/tmp/healthy') ? 0 : 1)"]
       interval: 30s
       timeout: 10s
       retries: 3
@@ -26,7 +21,7 @@ services:
     volumes:
       - pgdata:/var/lib/postgresql/data
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER:-uphold} -d ${POSTGRES_DB:-uphold_db}"]
+      test: ["CMD-SHELL", "pg_isready -U uphold -d uphold_alerts"]
       interval: 5s
       timeout: 5s
       retries: 5

index.js

@@ -1,9 +1,9 @@
+import fs from "node:fs";
 import { parseArgs } from "node:util";
 import { prefetchRates } from "./src/api.js";
 import { Bot } from "./src/bot.js";
 import logger from "./src/logger.js";
 import { initDB, insertIntoDB, closePool } from "./src/db.js";
-import { startServer } from "./src/server.js";
 
 process.on("uncaughtException", (err) => {
   logger.fatal(err, "Uncaught exception. Application crashing...");
@@ -31,6 +31,11 @@ const options = {
     short: "t",
     default: process.env.THRESHOLD || "0.01",
   },
+  stats: {
+    type: "boolean",
+    default: process.env.STATS === "true",
+    description: "Show performance stats periodically",
+  },
 };
 
 const { values } = parseArgs({
@@ -45,7 +50,7 @@ const interval = parseInt(values.interval, 10);
 const threshold = parseFloat(values.threshold);
 
 if (isNaN(interval) || interval < 100) {
-  logger.error("Interval must be a number larger than 100");
+  logger.error("Interval must be a number larger than 100ms");
   process.exit(1);
 }
 if (pairs.length === 0 || pairs.some((p) => !p.match(/^[A-Z]+-?[A-Z]+$/))) {
@@ -58,21 +63,22 @@ if (threshold <= 0 || threshold > 100) {
 }
 
 async function main() {
-  logger.info("Bot starting...");
+  logger.info("Uphold price alert bot starting...");
   logger.info(
     `[WATCHING] ${pairs.join(", ")} | Every ${interval}ms | Threshold ${threshold}%`,
   );
 
   await initDB();
-  startServer();
 
   try {
     await prefetchRates(pairs);
   } catch (err) {
-    logger.error(err, "Critical failure during cache population");
+    logger.error(err, "Critical failure during cache warming");
     process.exit(1);
   }
 
+  fs.promises.writeFile("/tmp/healthy", "ok");
+
   const handleAlert = async (alertData) => {
     await insertIntoDB(alertData);
   };

src/api.js

@@ -1,60 +1,49 @@
 import { BigNumber } from "bignumber.js";
 import PQueue from "p-queue";
 import logger from "./logger.js";
-import { incrementReq } from "./stats.js";
 
 const queue = new PQueue({ interval: 1000, intervalCap: 10 });
 
 export async function fetchRate(pair) {
   const key = pair.toUpperCase();
-  const max_retries = 3;
 
-  for (let attempt = 1; attempt <= max_retries; attempt++) {
-    let timeout;
-    try {
-      const res = await queue.add(async () => {
+  return queue.add(async () => {
+    for (let attempt = 1; attempt <= 3; attempt++) {
+      try {
         const controller = new AbortController();
-        timeout = setTimeout(() => controller.abort(), 5000);
+        const timeout = setTimeout(() => controller.abort(), 5000);
 
-        return fetch(`https://api.uphold.com/v0/ticker/${key}`, {
+        const res = await fetch(`https://api.uphold.com/v0/ticker/${key}`, {
           signal: controller.signal,
         });
-      });
 
-      clearTimeout(timeout);
+        clearTimeout(timeout);
 
-      if (res.status === 429) {
-        incrementReq("ratelimit");
-        throw new Error("Rate limited");
+        if (res.status === 429) throw new Error("Rate limited");
+        if (!res.ok) throw new Error(`HTTP ${res.status}`);
+
+        const data = await res.json();
+
+        if (!data.ask || isNaN(parseFloat(data.ask))) {
+          throw new Error("Invalid ask price");
+        }
+
+        return new BigNumber(data.ask);
+      } catch (err) {
+        clearTimeout(timeout);
+        if (attempt === 3) throw err;
+        await new Promise((r) => setTimeout(r, 500 * Math.pow(2, attempt - 1)));
       }
-
-      if (!res.ok) {
-        incrementReq("fail");
-        throw new Error(`HTTP ${res.status}`);
-      }
-
-      incrementReq("success");
-
-      const data = await res.json();
-
-      if (!data.ask || isNaN(parseFloat(data.ask))) {
-        throw new Error("Invalid ask price");
-      }
-
-      return new BigNumber(data.ask);
-    } catch (err) {
-      clearTimeout(timeout);
-      if (attempt === 3) throw err;
-      await new Promise((r) => setTimeout(r, 500 * Math.pow(2, attempt - 1)));
     }
-  }
+  });
 }
 
 export async function prefetchRates(pairs) {
+  logger.info({ pairs }, "Verifying pairs...");
   const results = await Promise.allSettled(pairs.map((p) => fetchRate(p)));
 
   const failed = results.filter((r) => r.status === "rejected");
   if (failed.length > 0) {
-    logger.warn(`[API] ${failed.length} pairs failed initial check`);
+    logger.warn(`[API] ${failed.length} pairs failed initial check.`);
   }
 }

src/bot.js

@@ -1,6 +1,5 @@
 import { fetchRate } from "./api.js";
 import logger from "./logger.js";
-import { updatePair, incrementAlerts } from "./stats.js";
 
 export class Bot {
   constructor(config, onAlert) {
@@ -33,20 +32,16 @@ export class Bot {
     try {
       const price = await fetchRate(this.pair);
 
-      updatePair(this.pair, price.toFixed(6));
-
       if (!this.lastPrice) {
         this.lastPrice = price;
         logger.info(`[${this.pair}] Initial price: ${price.toFixed(2)}`);
       } else {
-        // Using BigNumber
         const change = price
           .minus(this.lastPrice)
           .dividedBy(this.lastPrice)
           .multipliedBy(100);
 
         if (change.abs().gte(this.threshold)) {
-          incrementAlerts();
           const dir = change.gt(0) ? "UP" : "DOWN";
           logger.info(
             {
@@ -70,7 +65,6 @@ export class Bot {
           };
 
           try {
-            // onAlert must be fast
             await this.onAlert(alertData);
           } catch (err) {
             logger.error(

src/db.js

@@ -24,7 +24,7 @@ export function getPool() {
   });
 
   pool.on("error", (err) => {
-    logger.error(err, "[DB] Unexpected error on client", err);
+    logger.error(err, "[DB] Unexpected error on idle client", err);
   });
 
   return pool;
@@ -59,7 +59,7 @@ export async function initDB() {
     try {
       client = await currentPool.connect();
       await client.query(CREATE_TABLE_QUERY);
-      logger.info("[DB] Database initialized and connected");
+      logger.info("[DB] Database initialized and connected.");
       return;
     } catch (err) {
       if (i === maxRetries - 1) {
@@ -106,22 +106,11 @@ export async function insertIntoDB(data) {
     await getPool().query(query, values);
     logger.info(`[DB] Event saved for ${data.pair}`);
   } catch (err) {
-    logger.error(`[DB] Failed to save alert ${err.message}`);
+    logger.error(`[DB] Failed to save alert: ${err.message}`);
     throw err;
   }
 }
 
-export async function getAlerts(limit = 50) {
-  if (!pool) {
-    return [];
-  }
-  const res = await pool.query(
-    "SELECT * FROM alerts ORDER BY created_at DESC LIMIT $1",
-    [limit],
-  );
-  return res.rows;
-}
-
 export async function closePool() {
   if (pool) {
     await pool.end();

src/server.js

@@ -1,45 +0,0 @@
-import http from "node:http";
-import { URL } from "node:url";
-import { stats } from "./stats.js";
-import { getAlerts } from "./db.js";
-import logger from "./logger.js";
-
-const PORT = process.env.PORT || 3000;
-
-const sendJSON = (res, data, status = 200) => {
-  res.writeHead(status, { "Content-Type": "application/json" });
-  res.end(JSON.stringify(data, null, 2));
-};
-
-const server = http.createServer(async (req, res) => {
-  try {
-    const parsedUrl = new URL(req.url, `http://${req.headers.host}`);
-    const { pathname, searchParams } = parsedUrl;
-
-    if (req.method === "GET" && pathname === "/health") {
-      return sendJSON(res, { status: "ok", uptime: process.uptime() });
-    }
-
-    if (req.method === "GET" && pathname === "/stats") {
-      return sendJSON(res, stats);
-    }
-
-    if (req.method === "GET" && pathname === "/alerts") {
-      const limit = parseInt(searchParams.get("limit")) || 50;
-      const alerts = await getAlerts(limit);
-      return sendJSON(res, { count: alerts.length, data: alerts });
-    }
-
-    sendJSON(res, { error: "Not Found" }, 404);
-  } catch (err) {
-    logger.error(err, "API Error");
-    sendJSON(res, { error: "Internal Server Error" }, 500);
-  }
-});
-
-export const startServer = () => {
-  server.listen(PORT, () => {
-    logger.info(`[API] Server listening on port ${PORT}`);
-  });
-  return server;
-};

src/stats.js

@@ -1,31 +0,0 @@
-export const stats = {
-  startedAt: new Date().toISOString(),
-  api: {
-    totalRequests: 0,
-    successful: 0,
-    failed: 0,
-    rateLimited: 0,
-  },
-  bot: {
-    totalAlerts: 0,
-    activePairs: {},
-  },
-};
-
-export const incrementReq = (type) => {
-  stats.api.totalRequests++;
-  if (type === "success") stats.api.successful++;
-  if (type === "fail") stats.api.failed++;
-  if (type === "ratelimit") stats.api.rateLimited++;
-};
-
-export const updatePair = (pair, price) => {
-  stats.bot.activePairs[pair] = {
-    currentPrice: price,
-    lastUpdate: new Date().toISOString(),
-  };
-};
-
-export const incrementAlerts = () => {
-  stats.bot.totalAlerts++;
-};

tests/bot.test.js

@@ -128,6 +128,7 @@ describe("API", () => {
     vi.resetModules();
     nock.cleanAll();
 
+    // Import the actual module for these tests
     vi.doMock("../src/api.js", async () => {
       return await vi.importActual("../src/api.js");
     });