feat(database): makes it more robust and failsafe

Author: filipedeschamps

infra/database.js

@@ -1,7 +1,8 @@
-import { Pool } from 'pg';
+import { Pool, Client } from 'pg';
+import retry from 'async-retry';
 import { ServiceError } from 'errors/index.js';
 
-const poolConfiguration = {
+const configurations = {
   user: process.env.POSTGRES_USER,
   host: process.env.POSTGRES_HOST,
   database: process.env.POSTGRES_DB,
@@ -15,14 +16,17 @@ const poolConfiguration = {
 
 // https://github.com/filipedeschamps/tabnews.com.br/issues/84
 if (['test', 'development'].includes(process.env.NODE_ENV) || process.env.CI) {
-  delete poolConfiguration.ssl;
+  delete configurations.ssl;
 }
 
-const pool = new Pool(poolConfiguration);
+const pool = new Pool(configurations);
 
 async function query(query, params) {
+  let clientFromPool;
+
   try {
-    return await pool.query(query, params);
+    clientFromPool = await tryToGetNewClientFromPool();
+    return await clientFromPool.query(query, params);
   } catch (error) {
     const errorObject = new ServiceError({
       message: error.message,
@@ -34,15 +38,31 @@ async function query(query, params) {
     });
     console.error(errorObject);
     throw errorObject;
+  } finally {
+    if (clientFromPool) {
+      clientFromPool.release();
+    }
   }
 }
 
-async function getNewConnectedClient() {
-  // When manually creating a new connection like this,
-  // you need to make sure to close it afterward
-  // with the .end() method.
-  try {
+async function tryToGetNewClientFromPool() {
+  const clientFromPool = await retry(newClientFromPool, {
+    retries: 50,
+    minTimeout: 0,
+    factor: 1.3,
+  });
+
+  return clientFromPool;
+
+  async function newClientFromPool() {
     return await pool.connect();
+  }
+}
+
+async function getNewClient() {
+  try {
+    const client = await tryToGetNewClient();
+    return client;
   } catch (error) {
     const errorObject = new ServiceError({
       message: error.message,
@@ -52,9 +72,25 @@ async function getNewConnectedClient() {
     console.error(errorObject);
     throw errorObject;
   }
+
+  async function tryToGetNewClient() {
+    const client = await retry(newClient, {
+      retries: 50,
+      minTimeout: 0,
+      factor: 1.3,
+    });
+
+    return client;
+
+    async function newClient() {
+      const client = new Client(configurations);
+      await client.connect();
+      return client;
+    }
+  }
 }
 
 export default Object.freeze({
   query,
-  getNewConnectedClient,
+  getNewClient,
 });

infra/migrator.js

@@ -10,7 +10,7 @@ const defaultConfigurations = {
 };
 
 async function listPendingMigrations() {
-  const databaseClient = await database.getNewConnectedClient();
+  const databaseClient = await database.getNewClient();
 
   try {
     const pendingMigrations = await migrationRunner({
@@ -28,7 +28,7 @@ async function listPendingMigrations() {
 }
 
 async function runPendingMigrations() {
-  const databaseClient = await database.getNewConnectedClient();
+  const databaseClient = await database.getNewClient();
 
   try {
     const migratedMigrations = await migrationRunner({

models/health.js

@@ -30,7 +30,10 @@ async function getDependencies() {
 async function checkDatabaseDependency() {
   let result;
   try {
-    const maxConnectionsResult = await database.query('SHOW max_connections');
+    const maxConnectionsResult = await database.query(
+      'SELECT datconnlimit as max_connections FROM pg_database WHERE datname = $1',
+      [process.env.POSTGRES_DB]
+    );
     const maxConnectionsValue = maxConnectionsResult.rows[0].max_connections;
 
     const openConnectionsResult = await database.query(

tests/orchestrator.js

@@ -38,7 +38,7 @@ async function waitForAllServices() {
         if (tries >= 25) {
           console.log(`> Trying to connect to Database #${tries}. Are you running the Postgres container?`);
         }
-        const connection = await database.getNewConnectedClient();
+        const connection = await database.getNewClient();
         await connection.end();
       },
       {
@@ -69,7 +69,7 @@ async function waitForAllServices() {
 }
 
 async function dropAllTables() {
-  const databaseClient = await database.getNewConnectedClient();
+  const databaseClient = await database.getNewClient();
   await databaseClient.query('drop schema public cascade; create schema public;');
 
   await databaseClient.end();