Add a logging sample (#1078)

Author: jhuleatt

2nd-gen/monitor-cloud-logging/README.md

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+# Firebase SDK for Cloud Functions Quickstart - Structured Logs
+
+This quickstart demonstrates using the **`logger`** subpackage to write structured logs to Cloud Logging.
+
+Learn more about logging in Cloud Functions for Firebase [in the docs](https://firebase.google.com/docs/functions/writing-and-viewing-logs).
+
+## License
+
+© Google, 2023. Licensed under an [Apache-2](../../../LICENSE) license.

2nd-gen/monitor-cloud-logging/firebase.json

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+{
+  "functions": [
+    {
+      "source": "functions",
+      "codebase": "default",
+      "ignore": [
+        "node_modules",
+        ".git",
+        "firebase-debug.log",
+        "firebase-debug.*.log"
+      ],
+      "predeploy": [
+        "npm --prefix \"$RESOURCE_DIR\" run lint"
+      ]
+    }
+  ]
+}

2nd-gen/monitor-cloud-logging/functions/.eslintrc.js

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+module.exports = {
+  env: {
+    es6: true,
+    node: true,
+  },
+  parserOptions: {
+    "ecmaVersion": 2018,
+  },
+  extends: [
+    "eslint:recommended",
+    "google",
+  ],
+  rules: {
+    "no-restricted-globals": ["error", "name", "length"],
+    "prefer-arrow-callback": "error",
+    "quotes": ["error", "double", {"allowTemplateLiterals": true}],
+  },
+  overrides: [
+    {
+      files: ["**/*.spec.*"],
+      env: {
+        mocha: true,
+      },
+      rules: {},
+    },
+  ],
+  globals: {},
+};

2nd-gen/monitor-cloud-logging/functions/index.js

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+/**
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const {onRequest} = require("firebase-functions/v2/https");
+const {
+  onRegressionAlertPublished,
+} = require("firebase-functions/v2/alerts/crashlytics");
+
+// [START loggerImport]
+// All available logging functions
+const {
+  log,
+  info,
+  debug,
+  warn,
+  error,
+  write,
+} = require("firebase-functions/logger");
+// [END loggerImport]
+
+const {initializeApp} = require("firebase-admin/app");
+const {getFirestore} = require("firebase-admin/firestore");
+// Initialize admin sdk for Firestore read in getInspirationalQuote
+initializeApp();
+
+// [START helloLogs]
+exports.helloWorld = onRequest((request, response) => {
+  // sends a log to Cloud Logging
+  log("Hello logs!");
+
+  response.send("Hello from Firebase!");
+});
+// [END helloLogs]
+
+// [START logsKitchenSink]
+exports.getInspirationalQuote = onRequest(async (request, response) => {
+  const db = getFirestore();
+  const today = new Date();
+  const quoteOfTheMonthRef = db
+      .collection("quotes")
+      .doc(today.getFullYear())
+      .collection("months")
+      .doc(today.getMonth());
+
+  const DEFAULT_QUOTE =
+      "You miss 100% of the shots you don't take. -Wayne Gretzky";
+  let quote;
+  try {
+    const quoteOfTheMonthDocSnap = await quoteOfTheMonthRef.get();
+
+    // Attach relevant debugging information with debug()
+    debug("Monthly quote fetch result", {
+      docRef: quoteOfTheMonthRef.path,
+      exists: quoteOfTheMonthDocSnap.exists,
+      createTime: quoteOfTheMonthDocSnap.createTime,
+    });
+
+    if (quoteOfTheMonthDocSnap.exists) {
+      quote = quoteOfTheMonthDocSnap.data().text;
+    } else {
+      // Use warn() for lower-severity issues than error()
+      warn("Quote not found for month, sending default instead", {
+        docRef: quoteOfTheMonthRef.path,
+        dateRequested: today.toLocaleDateString("en-US"),
+      });
+
+      quote = DEFAULT_QUOTE;
+    }
+  } catch (e) {
+    // Attach stack trace to errors
+    error("Unable to read quote from Firestore, sending default instead",
+        {message: e.stack});
+
+    quote = DEFAULT_QUOTE;
+  }
+
+  // Attach relevant structured data to any log
+  info("Sending a quote!", {quote: quote});
+  response.json({inspirationalQuote: quote});
+});
+// [END logsKitchenSink]
+
+// [START customLogWrite]
+exports.appHasARegression = onRegressionAlertPublished((event) => {
+  write({
+    // write() lets you set additional severity levels
+    // beyond the built-in logger functions
+    severity: "EMERGENCY",
+    message: "Regression in production app",
+    issue: event.data.payload.issue,
+    lastOccurred: event.data.payload.resolveTime,
+  });
+});
+// [END customLogWrite]

2nd-gen/monitor-cloud-logging/functions/package.json

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+{
+  "name": "functions",
+  "description": "Cloud Functions for Firebase",
+  "scripts": {
+    "lint": "eslint .",
+    "serve": "firebase emulators:start --only functions",
+    "shell": "firebase functions:shell",
+    "start": "npm run shell",
+    "deploy": "firebase deploy --only functions",
+    "logs": "firebase functions:log"
+  },
+  "engines": {
+    "node": "16"
+  },
+  "main": "index.js",
+  "dependencies": {
+    "firebase-admin": "^11.5.0",
+    "firebase-functions": "^4.2.0"
+  },
+  "devDependencies": {
+    "eslint": "^8.15.0",
+    "eslint-config-google": "^0.14.0",
+    "firebase-functions-test": "^3.0.0"
+  },
+  "private": true
+}