Add Dynamic Server Configuration (#2385) by Bruception

* Add no frontend script

* Define context middleware

* Define base configuration schema

* Define configuration DAO

* Setup context middleware and live configuration fetch

* Remove patch configuration method

* Rename files for consistency

* Use plain object check

* Use plain object

* modified base configuration

* renamed config property

* brought back 2 properties

Co-authored-by: Miodec <bartnikjack@gmail.com>

backend/api/routes/quotes.js

@@ -8,8 +8,8 @@ const RateLimit = require("../../middlewares/rate-limit");
 const {
   asyncHandlerWrapper,
   requestValidation,
-} = require("../../middlewares/apiUtils");
-const SUPPORTED_QUOTE_LANGUAGES = require("../../constants/quoteLanguages");
+} = require("../../middlewares/api-utils");
+const SUPPORTED_QUOTE_LANGUAGES = require("../../constants/quote-languages");
 
 const quotesRouter = Router();
 

backend/constants/base-configuration.js

@@ -0,0 +1,18 @@
+/**
+ * This is the base schema for the configuration of the API backend.
+ * To add a new configuration. Simply add it to this object.
+ * When changing this template, please follow the principle of "Secure by default" (https://en.wikipedia.org/wiki/Secure_by_default).
+ */
+const BASE_CONFIGURATION = {
+  maintenance: false,
+  quoteReport: {
+    enabled: false,
+    maxReports: 0,
+    contentReportLimit: 0,
+  },
+  quoteSubmit: {
+    enabled: false,
+  },
+};
+
+module.exports = BASE_CONFIGURATION;

backend/dao/configuration.js

@@ -0,0 +1,84 @@
+const _ = require("lodash");
+const { mongoDB } = require("../init/mongodb");
+const BASE_CONFIGURATION = require("../constants/base-configuration");
+const Logger = require("../handlers/logger.js");
+
+const CONFIG_UPDATE_INTERVAL = 10 * 60 * 1000; // 10 Minutes
+
+function mergeConfigurations(baseConfiguration, liveConfiguration) {
+  if (
+    !_.isPlainObject(baseConfiguration) ||
+    !_.isPlainObject(liveConfiguration)
+  ) {
+    return;
+  }
+
+  function merge(base, source) {
+    const commonKeys = _.intersection(_.keys(base), _.keys(source));
+
+    commonKeys.forEach((key) => {
+      const baseValue = base[key];
+      const sourceValue = source[key];
+
+      if (_.isPlainObject(baseValue) && _.isPlainObject(sourceValue)) {
+        merge(baseValue, sourceValue);
+      } else if (typeof baseValue === typeof sourceValue) {
+        base[key] = sourceValue;
+      }
+    });
+  }
+
+  merge(baseConfiguration, liveConfiguration);
+}
+
+class ConfigurationDAO {
+  static configuration = Object.freeze(BASE_CONFIGURATION);
+  static lastFetchTime = 0;
+
+  static async getCachedConfiguration(attemptCacheUpdate = false) {
+    if (
+      attemptCacheUpdate &&
+      this.lastFetchTime < Date.now() - CONFIG_UPDATE_INTERVAL
+    ) {
+      Logger.log("stale_configuration", "Cached configuration is stale.");
+      return await this.getLiveConfiguration();
+    }
+    return this.configuration;
+  }
+
+  static async getLiveConfiguration() {
+    this.lastFetchTime = Date.now();
+
+    try {
+      const liveConfiguration = await mongoDB()
+        .collection("configuration")
+        .findOne();
+
+      if (liveConfiguration) {
+        const baseConfiguration = _.cloneDeep(BASE_CONFIGURATION);
+        mergeConfigurations(baseConfiguration, liveConfiguration);
+
+        this.configuration = baseConfiguration;
+      } else {
+        await mongoDB()
+          .collection("configuration")
+          .insertOne(BASE_CONFIGURATION); // Seed the base configuration.
+      }
+      Logger.log(
+        "fetch_configuration_success",
+        "Successfully fetched live configuration."
+      );
+    } catch (error) {
+      Logger.log(
+        "fetch_configuration_failure",
+        `Could not fetch configuration: ${error.message}`
+      );
+    }
+
+    this.configuration = Object.freeze(this.configuration);
+
+    return this.configuration;
+  }
+}
+
+module.exports = ConfigurationDAO;

backend/jobs/index.js

@@ -1,4 +1,4 @@
-const updateLeaderboards = require("./updateLeaderboards");
-const deleteOldLogs = require("./deleteOldLogs");
+const updateLeaderboards = require("./update-leaderboards");
+const deleteOldLogs = require("./delete-old-logs");
 
 module.exports = [updateLeaderboards, deleteOldLogs];

backend/middlewares/context.js

@@ -0,0 +1,13 @@
+const ConfigurationDAO = require("../dao/configuration");
+
+async function contextMiddleware(req, res, next) {
+  const configuration = await ConfigurationDAO.getCachedConfiguration(true);
+
+  req.context = {
+    configuration,
+  };
+
+  next();
+}
+
+module.exports = contextMiddleware;

backend/server.js

@@ -10,6 +10,8 @@ const serviceAccount = require("./credentials/serviceAccountKey.json");
 const { connectDB, mongoDB } = require("./init/mongodb");
 const jobs = require("./jobs");
 const addApiRoutes = require("./api/routes");
+const contextMiddleware = require("./middlewares/context");
+const ConfigurationDAO = require("./dao/configuration");
 
 const PORT = process.env.PORT || 5005;
 
@@ -21,8 +23,13 @@ app.use(cors());
 
 app.set("trust proxy", 1);
 
+app.use(contextMiddleware);
+
 app.use((req, res, next) => {
-  if (process.env.MAINTENANCE === "true") {
+  if (
+    process.env.MAINTENANCE === "true" ||
+    req.context.configuration.maintenance
+  ) {
     res.status(503).json({ message: "Server is down for maintenance" });
   } else {
     next();
@@ -79,6 +86,7 @@ app.listen(PORT, async () => {
   admin.initializeApp({
     credential: admin.credential.cert(serviceAccount),
   });
+  await ConfigurationDAO.getLiveConfiguration();
 
   console.log("Starting cron jobs...");
   jobs.forEach((job) => job.start());

package-lock.json

@@ -8208,8 +8208,7 @@
     "lodash": {
       "version": "4.17.21",
       "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz",
-      "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==",
-      "dev": true
+      "integrity": "sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg=="
     },
     "lodash.camelcase": {
       "version": "4.3.0",

package.json

@@ -7,6 +7,7 @@
     "build": "npx gulp build",
     "start:dev": "npm run build && concurrently --kill-others \"npx gulp watch\" \"nodemon --watch ./backend ./backend/server.js\" \"firebase serve --only hosting\"",
     "start:dev:nodb": "npm run build && concurrently --kill-others \"npx gulp watch\" \"firebase serve --only hosting\"",
+    "start:dev:nofe": "nodemon --watch ./backend ./backend/server.js",
     "deploy:live": "npm run build && firebase deploy -P live --only hosting"
   },
   "engines": {
@@ -64,6 +65,7 @@
     "helmet": "^4.6.0",
     "howler": "^2.2.1",
     "joi": "^17.6.0",
+    "lodash": "4.17.21",
     "moment-timezone": "^0.5.33",
     "mongodb": "^3.6.9",
     "node-fetch": "^2.6.7",