feat: add optional MongoDB replica deployment (#765)

src/config.ts

@@ -26,6 +26,12 @@ interface Config {
   DB_USERNAME: string;
   DB_PASSWORD: string;
   DB_HOSTNAME: string;
+  /**
+   * Complete MongoDB connection string. When set, this takes precedence over
+   * DB_USERNAME, DB_PASSWORD, and DB_HOSTNAME and supports replica-set seed
+   * lists and options.
+   */
+  MONGODB_URI: string;
   FOLDER: string;
   additionalExtensions: string[];
   S3_BUCKET: string | null;
@@ -73,6 +79,7 @@ const config: Config = {
   DB_USERNAME: "admin",
   DB_PASSWORD: "password",
   DB_HOSTNAME: "mongodb",
+  MONGODB_URI: "",
   REDIS_HOSTNAME: "redis",
   REDIS_PORT: 6379,
   FOLDER: resolve(__dirname, "..", "repositories"),
@@ -142,8 +149,10 @@ if (isProduction) {
   const insecureDefaults: [string, string][] = [
     ["CLIENT_ID", "CLIENT_ID"],
     ["CLIENT_SECRET", "CLIENT_SECRET"],
-    ["DB_PASSWORD", "password"],
   ];
+  if (!config.MONGODB_URI) {
+    insecureDefaults.push(["DB_PASSWORD", "password"]);
+  }
   for (const [key, badValue] of insecureDefaults) {
     if ((config as unknown as Record<string, unknown>)[key] === badValue) {
       throw new Error(

src/server/database.ts

@@ -8,7 +8,12 @@ import PullRequest from "../core/PullRequest";
 import AnonymizedGistModel from "../core/model/anonymizedGists/anonymizedGists.model";
 import Gist from "../core/Gist";
 
-const MONGO_URL = `mongodb://${config.DB_USERNAME}:${config.DB_PASSWORD}@${config.DB_HOSTNAME}:27017/`;
+export function getMongoUrl(): string {
+  return (
+    config.MONGODB_URI ||
+    `mongodb://${config.DB_USERNAME}:${config.DB_PASSWORD}@${config.DB_HOSTNAME}:27017/production`
+  );
+}
 
 export const database = mongoose.connection;
 
@@ -16,11 +21,12 @@ export let isConnected = false;
 
 export async function connect() {
   mongoose.set("strictQuery", false);
-  await mongoose.connect(MONGO_URL + "production", {
-    authSource: "admin",
+  const options: ConnectOptions = {
     appName: "Anonymous GitHub Server",
     compressors: "zstd",
-  } as ConnectOptions);
+  };
+  if (!config.MONGODB_URI) options.authSource = "admin";
+  await mongoose.connect(getMongoUrl(), options);
   isConnected = true;
 
   return database;