MongoDB appName & MySQL program_name (#291)

* Identify powersync in MongoDB connections.

* Add `program_name` for MySQL.

* Add changeset.

Author: rkistner

.changeset/slow-hounds-walk.md

@@ -0,0 +1,10 @@
+---
+'@powersync/service-module-mongodb-storage': patch
+'@powersync/service-module-mongodb': patch
+'@powersync/service-module-mysql': patch
+'@powersync/lib-service-mongodb': patch
+'@powersync/service-core': patch
+'@powersync/service-image': patch
+---
+
+Add 'powersync' as the app name for MongoDB and MySQL connections.

libs/lib-mongodb/src/db/mongo.ts

@@ -1,7 +1,6 @@
 import * as mongo from 'mongodb';
 import * as timers from 'timers/promises';
 import { BaseMongoConfigDecoded, normalizeMongoConfig } from '../types/types.js';
-import { validateIpHostname } from '@powersync/lib-services-framework';
 
 /**
  * Time for new connection to timeout.
@@ -33,6 +32,9 @@ export interface MongoConnectionOptions {
   maxPoolSize: number;
 }
 
+/**
+ * Create a MongoClient for the storage database.
+ */
 export function createMongoClient(config: BaseMongoConfigDecoded, options?: MongoConnectionOptions) {
   const normalized = normalizeMongoConfig(config);
   return new mongo.MongoClient(normalized.uri, {
@@ -47,6 +49,9 @@ export function createMongoClient(config: BaseMongoConfigDecoded, options?: Mong
     // How long to wait for new primary selection
     serverSelectionTimeoutMS: 30_000,
 
+    // Identify the client
+    appName: 'powersync-storage',
+
     lookup: normalized.lookup,
 
     // Avoid too many connections:

modules/module-mongodb-storage/src/storage/implementation/util.ts

@@ -107,7 +107,7 @@ export function replicaIdToSubkey(table: bson.ObjectId, id: storage.ReplicaId):
 /**
  * Helper function for creating a MongoDB client from consumers of this package
  */
-export const createMongoClient = (url: string, options?: mongo.MongoClientOptions) => {
+const createMongoClient = (url: string, options?: mongo.MongoClientOptions) => {
   return new mongo.MongoClient(url, options);
 };
 

modules/module-mongodb/src/replication/MongoManager.ts

@@ -3,6 +3,9 @@ import { mongo } from '@powersync/lib-service-mongodb';
 import { NormalizedMongoConnectionConfig } from '../types/types.js';
 import { BSON_DESERIALIZE_DATA_OPTIONS } from '@powersync/service-core';
 
+/**
+ * Manage a MongoDB source database connection.
+ */
 export class MongoManager {
   public readonly client: mongo.MongoClient;
   public readonly db: mongo.Db;
@@ -26,6 +29,9 @@ export class MongoManager {
       // How long to wait for new primary selection
       serverSelectionTimeoutMS: 30_000,
 
+      // Identify the client
+      appName: 'powersync',
+
       // Avoid too many connections:
       // 1. It can overwhelm the source database.
       // 2. Processing too many queries in parallel can cause the process to run out of memory.

modules/module-mysql/src/replication/BinLogReplicationJob.ts

@@ -55,7 +55,16 @@ export class BinLogReplicationJob extends replication.AbstractReplicationJob {
     // such as caused by cached PG schemas.
     const connectionManager = this.connectionFactory.create({
       // Pool connections are only used intermittently.
-      idleTimeout: 30_000
+      idleTimeout: 30_000,
+
+      connectAttributes: {
+        // https://dev.mysql.com/doc/refman/8.0/en/performance-schema-connection-attribute-tables.html
+        // These do not appear to be supported by Zongji yet, so we only specify it here.
+        // Query using `select * from performance_schema.session_connect_attrs`.
+        program_name: 'powersync'
+
+        // _client_name and _client_version is specified by the driver
+      }
     });
     try {
       await this.rateLimiter?.waitUntilAllowed({ signal: this.abortController.signal });