Add GCP telemetry script (#1033)

Adds a script -  `scripts/telemetry_gcp.js` - to simplify setting up a local OpenTelemetry collector that forwards data to Google Cloud. This is a follow up to the script for local telemetry `scripts/local_telemetry.js` added in #1015.

This script automates downloading necessary binaries, configuring the collector, and updating workspace settings.

Also includes `scripts/telemetry_utils.js` with shared helper functions for telemetry scripts. Will refactor `scripts/local_t elemetry.js` in next steps to use this shared functionality.

Updates `docs/core/telemetry.md` to include:
- A new "Quick Start" section
- Detailed instructions for the new GCP automated script
- Reorganization of existing sections for clarity

#750 

---
```
✨ Starting Local Telemetry Exporter for Google Cloud ✨
⚙️  Enabled telemetry in workspace settings.
🔧 Set telemetry OTLP endpoint to http://localhost:4317.
✅ Workspace settings updated.
✅ Using Google Cloud Project ID: foo-bar

🔑 Please ensure you are authenticated with Google Cloud:
  - Run `gcloud auth application-default login` OR ensure `GOOGLE_APPLICATION_CREDENTIALS` environment variable points to a valid service account key.
  - The account needs "Cloud Trace Agent", "Monitoring Metric Writer", and "Logs Writer" roles.
✅ otelcol-contrib already exists at /Users/jerop/github/gemini-cli/.gemini/otel/bin/otelcol-contrib
🧹 Cleaning up old processes and logs...
✅ Deleted old GCP collector log.
📄 Wrote OTEL collector config to /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.yaml
🚀 Starting OTEL collector for GCP... Logs: /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.log
⏳ Waiting for OTEL collector to start (PID: 65145)...
✅ OTEL collector started successfully on port 4317.

✨ Local OTEL collector for GCP is running.

📄 Collector logs are being written to: /Users/jerop/github/gemini-cli/.gemini/otel/collector-gcp.log

📊 View your telemetry data in Google Cloud Console:
   - Traces: https://console.cloud.google.com/traces/list?project=foo-bar
   - Metrics: https://console.cloud.google.com/monitoring/metrics-explorer?project=foo-bar
   - Logs: https://console.cloud.google.com/logs/query;query=logName%3D%22projects%2Ffoo-bar%2Flogs%2Fgemini_cli%22?project=foo-bar

Press Ctrl+C to exit.
^C
👋 Shutting down...
⚙️ Disabled telemetry in workspace settings.
🔧 Cleared telemetry OTLP endpoint.
✅ Workspace settings updated.
🛑 Stopping otelcol-contrib (PID: 65145)...
✅ otelcol-contrib stopped.
```

1 files changed, 362 insertions, 0 deletions

diff --git a/scripts/telemetry_utils.js b/scripts/telemetry_utils.js
new file mode 100644
index 00000000..62eb910b
--- /dev/null
+++ b/scripts/telemetry_utils.js
@@ -0,0 +1,362 @@
+#!/usr/bin/env node
+
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import path from 'path';
+import fs from 'fs';
+import net from 'net';
+import os from 'os';
+import { execSync } from 'child_process'; // Removed spawn, it's not used here
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+export const ROOT_DIR = path.resolve(__dirname, '..');
+export const GEMINI_DIR = path.join(ROOT_DIR, '.gemini');
+export const OTEL_DIR = path.join(GEMINI_DIR, 'otel');
+export const BIN_DIR = path.join(OTEL_DIR, 'bin');
+export const WORKSPACE_SETTINGS_FILE = path.join(GEMINI_DIR, 'settings.json');
+
+export function getJson(url) {
+  const tmpFile = path.join(
+    os.tmpdir(),
+    `gemini-cli-releases-${Date.now()}.json`,
+  );
+  try {
+    execSync(
+      `curl -sL -H "User-Agent: gemini-cli-dev-script" -o "${tmpFile}" "${url}"`,
+      { stdio: 'pipe' },
+    );
+    const content = fs.readFileSync(tmpFile, 'utf-8');
+    return JSON.parse(content);
+  } catch (e) {
+    console.error(`Failed to fetch or parse JSON from ${url}`);
+    throw e;
+  } finally {
+    if (fs.existsSync(tmpFile)) {
+      fs.unlinkSync(tmpFile);
+    }
+  }
+}
+
+export function downloadFile(url, dest) {
+  try {
+    execSync(`curl -fL -sS -o "${dest}" "${url}"`, {
+      stdio: 'pipe',
+    });
+    return dest;
+  } catch (e) {
+    console.error(`Failed to download file from ${url}`);
+    throw e;
+  }
+}
+
+export function findFile(startPath, filter) {
+  if (!fs.existsSync(startPath)) {
+    return null;
+  }
+  const files = fs.readdirSync(startPath);
+  for (const file of files) {
+    const filename = path.join(startPath, file);
+    const stat = fs.lstatSync(filename);
+    if (stat.isDirectory()) {
+      const result = findFile(filename, filter);
+      if (result) return result;
+    } else if (filter(file)) {
+      return filename;
+    }
+  }
+  return null;
+}
+
+export function fileExists(filePath) {
+  return fs.existsSync(filePath);
+}
+
+export function readJsonFile(filePath) {
+  if (!fileExists(filePath)) {
+    return {};
+  }
+  const content = fs.readFileSync(filePath, 'utf-8');
+  try {
+    return JSON.parse(content);
+  } catch (e) {
+    console.error(`Error parsing JSON from ${filePath}: ${e.message}`);
+    return {};
+  }
+}
+
+export function writeJsonFile(filePath, data) {
+  fs.writeFileSync(filePath, JSON.stringify(data, null, 2));
+}
+
+export function waitForPort(port, timeout = 10000) {
+  return new Promise((resolve, reject) => {
+    const startTime = Date.now();
+    const tryConnect = () => {
+      const socket = new net.Socket();
+      socket.once('connect', () => {
+        socket.end();
+        resolve();
+      });
+      socket.once('error', (_) => {
+        if (Date.now() - startTime > timeout) {
+          reject(new Error(`Timeout waiting for port ${port} to open.`));
+        } else {
+          setTimeout(tryConnect, 500);
+        }
+      });
+      socket.connect(port, 'localhost');
+    };
+    tryConnect();
+  });
+}
+
+export async function ensureBinary(
+  executableName,
+  repo,
+  assetNameCallback,
+  binaryNameInArchive,
+  isJaeger = false,
+) {
+  const executablePath = path.join(BIN_DIR, executableName);
+  if (fileExists(executablePath)) {
+    console.log(`✅ ${executableName} already exists at ${executablePath}`);
+    return executablePath;
+  }
+
+  console.log(`🔍 ${executableName} not found. Downloading from ${repo}...`);
+
+  const platform = process.platform === 'win32' ? 'windows' : process.platform;
+  const arch = process.arch === 'x64' ? 'amd64' : process.arch;
+  const ext = platform === 'windows' ? 'zip' : 'tar.gz';
+
+  if (isJaeger && platform === 'windows' && arch === 'arm64') {
+    console.warn(
+      `⚠️ Jaeger does not have a release for Windows on ARM64. Skipping.`,
+    );
+    return null;
+  }
+
+  let release;
+  let asset;
+
+  if (isJaeger) {
+    console.log(`🔍 Finding latest Jaeger v2+ asset...`);
+    const releases = getJson(`https://api.github.com/repos/${repo}/releases`);
+    const sortedReleases = releases
+      .filter((r) => !r.prerelease && r.tag_name.startsWith('v'))
+      .sort((a, b) => {
+        const aVersion = a.tag_name.substring(1).split('.').map(Number);
+        const bVersion = b.tag_name.substring(1).split('.').map(Number);
+        for (let i = 0; i < Math.max(aVersion.length, bVersion.length); i++) {
+          if ((aVersion[i] || 0) > (bVersion[i] || 0)) return -1;
+          if ((aVersion[i] || 0) < (bVersion[i] || 0)) return 1;
+        }
+        return 0;
+      });
+
+    for (const r of sortedReleases) {
+      const expectedSuffix =
+        platform === 'windows'
+          ? `-${platform}-${arch}.zip`
+          : `-${platform}-${arch}.tar.gz`;
+      const foundAsset = r.assets.find(
+        (a) =>
+          a.name.startsWith('jaeger-2.') && a.name.endsWith(expectedSuffix),
+      );
+
+      if (foundAsset) {
+        release = r;
+        asset = foundAsset;
+        console.log(
+          `⬇️  Found ${asset.name} in release ${r.tag_name}, downloading...`,
+        );
+        break;
+      }
+    }
+    if (!asset) {
+      throw new Error(
+        `Could not find a suitable Jaeger v2 asset for platform ${platform}/${arch}.`,
+      );
+    }
+  } else {
+    release = getJson(`https://api.github.com/repos/${repo}/releases/latest`);
+    const version = release.tag_name.startsWith('v')
+      ? release.tag_name.substring(1)
+      : release.tag_name;
+    const assetName = assetNameCallback(version, platform, arch, ext);
+    asset = release.assets.find((a) => a.name === assetName);
+    if (!asset) {
+      throw new Error(
+        `Could not find a suitable asset for ${repo} (version ${version}) on platform ${platform}/${arch}. Searched for: ${assetName}`,
+      );
+    }
+  }
+
+  const downloadUrl = asset.browser_download_url;
+  const tmpDir = fs.mkdtempSync(
+    path.join(os.tmpdir(), 'gemini-cli-telemetry-'),
+  );
+  const archivePath = path.join(tmpDir, asset.name);
+
+  try {
+    console.log(`⬇️  Downloading ${asset.name}...`);
+    downloadFile(downloadUrl, archivePath);
+    console.log(`📦 Extracting ${asset.name}...`);
+
+    const actualExt = asset.name.endsWith('.zip') ? 'zip' : 'tar.gz';
+
+    if (actualExt === 'zip') {
+      execSync(`unzip -o "${archivePath}" -d "${tmpDir}"`, { stdio: 'pipe' });
+    } else {
+      execSync(`tar -xzf "${archivePath}" -C "${tmpDir}"`, { stdio: 'pipe' });
+    }
+
+    const nameToFind = binaryNameInArchive || executableName;
+    const foundBinaryPath = findFile(tmpDir, (file) => {
+      if (platform === 'windows') {
+        return file === `${nameToFind}.exe`;
+      }
+      return file === nameToFind;
+    });
+
+    if (!foundBinaryPath) {
+      throw new Error(
+        `Could not find binary "${nameToFind}" in extracted archive at ${tmpDir}. Contents: ${fs.readdirSync(tmpDir).join(', ')}`,
+      );
+    }
+
+    fs.renameSync(foundBinaryPath, executablePath);
+
+    if (platform !== 'windows') {
+      fs.chmodSync(executablePath, '755');
+    }
+
+    console.log(`✅ ${executableName} installed at ${executablePath}`);
+    return executablePath;
+  } finally {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+    if (fs.existsSync(archivePath)) {
+      fs.unlinkSync(archivePath);
+    }
+  }
+}
+
+export function manageTelemetrySettings(
+  enable,
+  oTelEndpoint = 'http://localhost:4317',
+  originalSandboxSettingToRestore,
+) {
+  const workspaceSettings = readJsonFile(WORKSPACE_SETTINGS_FILE);
+  const currentSandboxSetting = workspaceSettings.sandbox;
+  let settingsModified = false;
+
+  if (enable) {
+    if (workspaceSettings.telemetry !== true) {
+      workspaceSettings.telemetry = true;
+      settingsModified = true;
+      console.log('⚙️  Enabled telemetry in workspace settings.');
+    }
+    if (workspaceSettings.sandbox !== false) {
+      workspaceSettings.sandbox = false;
+      settingsModified = true;
+      console.log('✅ Disabled sandbox mode for telemetry.');
+    }
+    if (workspaceSettings.telemetryOtlpEndpoint !== oTelEndpoint) {
+      workspaceSettings.telemetryOtlpEndpoint = oTelEndpoint;
+      settingsModified = true;
+      console.log(`🔧 Set telemetry OTLP endpoint to ${oTelEndpoint}.`);
+    }
+  } else {
+    if (workspaceSettings.telemetry === true) {
+      delete workspaceSettings.telemetry;
+      settingsModified = true;
+      console.log('⚙️ Disabled telemetry in workspace settings.');
+    }
+    if (workspaceSettings.telemetryOtlpEndpoint) {
+      delete workspaceSettings.telemetryOtlpEndpoint;
+      settingsModified = true;
+      console.log('🔧 Cleared telemetry OTLP endpoint.');
+    }
+    if (
+      originalSandboxSettingToRestore !== undefined &&
+      workspaceSettings.sandbox !== originalSandboxSettingToRestore
+    ) {
+      workspaceSettings.sandbox = originalSandboxSettingToRestore;
+      settingsModified = true;
+      console.log('✅ Restored original sandbox setting.');
+    }
+  }
+
+  if (settingsModified) {
+    writeJsonFile(WORKSPACE_SETTINGS_FILE, workspaceSettings);
+    console.log('✅ Workspace settings updated.');
+  } else {
+    console.log(
+      enable
+        ? '✅ Workspace settings are already configured for telemetry.'
+        : '✅ Workspace settings already reflect telemetry disabled.',
+    );
+  }
+  return currentSandboxSetting;
+}
+
+export function registerCleanup(
+  getProcesses,
+  getLogFileDescriptors,
+  originalSandboxSetting,
+) {
+  let cleanedUp = false;
+  const cleanup = () => {
+    if (cleanedUp) return;
+    cleanedUp = true;
+
+    console.log('\n👋 Shutting down...');
+
+    manageTelemetrySettings(false, null, originalSandboxSetting);
+
+    const processes = getProcesses ? getProcesses() : [];
+    processes.forEach((proc) => {
+      if (proc && proc.pid) {
+        const name = path.basename(proc.spawnfile);
+        try {
+          console.log(`🛑 Stopping ${name} (PID: ${proc.pid})...`);
+          process.kill(proc.pid, 'SIGTERM');
+          console.log(`✅ ${name} stopped.`);
+        } catch (e) {
+          if (e.code !== 'ESRCH') {
+            console.error(`Error stopping ${name}: ${e.message}`);
+          }
+        }
+      }
+    });
+
+    const logFileDescriptors = getLogFileDescriptors
+      ? getLogFileDescriptors()
+      : [];
+    logFileDescriptors.forEach((fd) => {
+      if (fd) {
+        try {
+          fs.closeSync(fd);
+        } catch (_) {
+          /* no-op */
+        }
+      }
+    });
+  };
+
+  process.on('exit', cleanup);
+  process.on('SIGINT', () => process.exit(0));
+  process.on('SIGTERM', () => process.exit(0));
+  process.on('uncaughtException', (err) => {
+    console.error('Uncaught Exception:', err);
+    cleanup();
+    process.exit(1);
+  });
+}