Implement using pg_try_advisory_lock for db-migrations to be able to …

…run multiple instances again

So we now always do db-migrate at the startup of the program. This way, we are sure that the database in the program is compatible with the queries in the program. However, these migrations are not necessarily safe to run in parallel, so in this commit I added a setup to ensure that the db-migrations are not run in parallel even when we start multiple instances of the program.

package.json

@@ -12,6 +12,8 @@
     "build": "tsc",
     "swagger": "tsoa spec-and-routes",
     "dev": "node --import tsx --watch src/index.ts",
+    "docker-compose-test:up": "docker compose -f compose.test.yml up -d",
+    "docker-compose-test:down": "docker compose -f compose.test.yml down",
     "backup": "docker exec -it badgehub-api-db-1 /usr/bin/pg_dump --username badgehub badgehub -f /var/backup/data-backup-`date +\"%Y-%m-%dT%H:%m\"`.sql",
     "test": "vitest --coverage.enabled true",
     "db-migrate:up": "db-migrate up",

process.json

@@ -4,7 +4,7 @@
   "interpreter_args": "--import tsx",
   "name": "badgehub",
   "exec_mode": "cluster",
-  "instances": 1,
+  "instances": 4,
   "error_file": "./logs/error.log",
   "out_file": "./logs/access.log",
   "combine_logs": true

src/db/connectionPool.ts

@@ -20,3 +20,13 @@ export const getPool = () => {
   }
   return pool;
 };
+
+export const getClient = () => {
+  return new pg.Client({
+    host: POSTGRES_HOST,
+    database: POSTGRES_DB,
+    user: POSTGRES_USER,
+    password: POSTGRES_PASSWORD,
+    port: POSTGRES_PORT,
+  });
+};

src/db/migrations.ts

@@ -1,19 +1,31 @@
 import { exec } from "node:child_process";
+import { getClient } from "@db/connectionPool";
+
+const MIGRATION_LOCK_ID = 108;
 
 export async function runMigrations() {
   // This code runs the npm script 'db-migrate:up' to make sure all migrations are done
+  console.log(`Waiting for db-migrations lock [${MIGRATION_LOCK_ID}]`);
+  const dbClient = getClient();
+  await dbClient.connect();
+  await dbClient.query(`SELECT pg_advisory_lock($1)`, [MIGRATION_LOCK_ID]);
   console.log("Running migrations via child process");
-  return new Promise<void>((resolve, reject) => {
-    exec("npm run db-migrate:up", (error, stdout, stderr) => {
-      stdout && console.log(stdout);
-      stderr && console.error(stderr);
-      if (error) {
-        console.error(`Error running migrations: ${error}`);
-        reject(error);
-      } else {
-        resolve();
-      }
-      console.log("Migrations done");
+  try {
+    return await new Promise<void>((resolve, reject) => {
+      exec("npm run db-migrate:up", (error, stdout, stderr) => {
+        stdout && console.log(stdout);
+        stderr && console.error(stderr);
+        if (error) {
+          console.error(`Error running migrations: ${error}`);
+          reject(error);
+        } else {
+          resolve();
+        }
+        console.log("Migrations done");
+      });
     });
-  });
+  } finally {
+    await dbClient.end();
+    console.log("released db-migrations");
+  }
 }