Add Unix socket connection support to PostgreSQL session storage

Use pg-connection-string (already a declared dependency) to parse
connection URLs instead of manual URL decomposition. This preserves
all connection parameters including the host query parameter used
for Unix domain sockets (e.g. Google Cloud SQL Auth Proxy) and SSL
parameters.

Fixes #3113

Author: hashemHP

.changeset/add-unix-socket-support.md

@@ -0,0 +1,5 @@
+---
+'@shopify/shopify-app-session-storage-postgresql': minor
+---
+
+Add Unix socket connection support by using pg-connection-string to parse connection URLs instead of manual URL decomposition. This enables connecting via Unix domain sockets (e.g. Google Cloud SQL Auth Proxy) using the standard `?host=` query parameter, and also preserves SSL and other connection parameters that were previously dropped.

packages/apps/session-storage/shopify-app-session-storage-postgresql/README.md

@@ -36,6 +36,21 @@ const shopify = shopifyApp({
 });
 ```
 
+## Connecting via Unix Socket (e.g. Google Cloud SQL)
+
+When deploying on Google Cloud (Cloud Run, App Engine, GKE), the Cloud SQL Auth Proxy provides database connections through Unix sockets. You can connect by specifying the socket path via the `host` query parameter:
+
+```js
+const shopify = shopifyApp({
+  sessionStorage: new PostgreSQLSessionStorage(
+    'postgres://username:password@/database?host=/cloudsql/my-project:us-central1:my-instance',
+  ),
+  // ...
+});
+```
+
+This also works for any other environment where PostgreSQL is accessed via a Unix domain socket.
+
 ## Expiring Offline Access Tokens
 
 This storage adapter supports [expiring offline access tokens](https://shopify.dev/docs/apps/build/authentication-authorization/access-tokens/offline-access-tokens#step-7-get-a-new-access-token-exchange). When enabled, the adapter automatically stores and retrieves refresh tokens alongside your session data.

packages/apps/session-storage/shopify-app-session-storage-postgresql/src/__tests__/postgres-connection.test.ts

@@ -0,0 +1,97 @@
+import {parse} from 'pg-connection-string';
+
+/**
+ * Unit tests for the connection URL parsing logic used in PostgresConnection.
+ * These verify that pg-connection-string + decodeURIComponent produces the
+ * correct pool config for all supported URL formats, without requiring a
+ * running PostgreSQL instance.
+ */
+
+// Replicates the exact parsing logic from postgres-connection.ts init()
+function parseConnectionConfig(connectionString: string) {
+  const config = parse(connectionString);
+  if (config.database) {
+    config.database = decodeURIComponent(config.database);
+  }
+  return config;
+}
+
+// Replicates the exact logic from postgres-connection.ts getDatabase()
+function getDatabase(connectionString: string): string | undefined {
+  const database = parse(connectionString).database;
+  return database ? decodeURIComponent(database) : undefined;
+}
+
+describe('PostgresConnection URL parsing', () => {
+  it('parses a standard TCP connection URL with port', () => {
+    const config = parseConnectionConfig(
+      'postgres://user:password@localhost:5432/mydb',
+    );
+    expect(config.host).toBe('localhost');
+    expect(config.port).toBe('5432');
+    expect(config.user).toBe('user');
+    expect(config.password).toBe('password');
+    expect(config.database).toBe('mydb');
+  });
+
+  it('parses a TCP connection URL without port', () => {
+    const config = parseConnectionConfig(
+      'postgres://user:password@localhost/mydb',
+    );
+    expect(config.host).toBe('localhost');
+    expect(config.user).toBe('user');
+    expect(config.password).toBe('password');
+    expect(config.database).toBe('mydb');
+  });
+
+  it('parses a Unix socket URL with host query parameter', () => {
+    const config = parseConnectionConfig(
+      'postgres://user:password@/mydb?host=/cloudsql/my-project:us-central1:my-instance',
+    );
+    expect(config.host).toBe(
+      '/cloudsql/my-project:us-central1:my-instance',
+    );
+    expect(config.user).toBe('user');
+    expect(config.password).toBe('password');
+    expect(config.database).toBe('mydb');
+  });
+
+  it('decodes special characters in credentials and database name', () => {
+    const config = parseConnectionConfig(
+      'postgres://shop%26fy:passify%23%24@localhost:5432/shop%26test',
+    );
+    expect(config.user).toBe('shop&fy');
+    expect(config.password).toBe('passify#$');
+    expect(config.database).toBe('shop&test');
+  });
+
+  it('preserves SSL query parameters', () => {
+    const config = parseConnectionConfig(
+      'postgres://user:password@localhost/mydb?ssl=true',
+    );
+    expect(config.ssl).toBe(true);
+    expect(config.database).toBe('mydb');
+  });
+
+  describe('getDatabase', () => {
+    it('returns the decoded database name for a standard URL', () => {
+      expect(
+        getDatabase('postgres://user:pass@localhost:5432/mydb'),
+      ).toBe('mydb');
+    });
+
+    it('returns the decoded database name for a Unix socket URL', () => {
+      expect(
+        getDatabase(
+          'postgres://user:pass@/mydb?host=/cloudsql/project:region:instance',
+        ),
+      ).toBe('mydb');
+    });
+
+    it('decodes special characters in database name', () => {
+      expect(
+        getDatabase('postgres://user:pass@localhost/shop%26test'),
+      ).toBe('shop&test');
+    });
+  });
+});

packages/apps/session-storage/shopify-app-session-storage-postgresql/src/postgres-connection.ts

@@ -1,14 +1,15 @@
 import pg from 'pg';
+import {parse} from 'pg-connection-string';
 import {RdbmsConnection} from '@shopify/shopify-app-session-storage';
 
 export class PostgresConnection implements RdbmsConnection {
   sessionStorageIdentifier: string;
   private ready: Promise<void>;
   private pool: pg.Pool;
-  private dbUrl: URL;
+  private connectionString: string;
 
   constructor(dbUrl: string, sessionStorageIdentifier: string) {
-    this.dbUrl = new URL(dbUrl);
+    this.connectionString = dbUrl;
     this.ready = this.init();
     this.sessionStorageIdentifier = sessionStorageIdentifier;
   }
@@ -60,7 +61,8 @@ export class PostgresConnection implements RdbmsConnection {
   }
 
   public getDatabase(): string | undefined {
-    return decodeURIComponent(this.dbUrl.pathname.slice(1));
+    const database = parse(this.connectionString).database;
+    return database ? decodeURIComponent(database) : undefined;
   }
 
   async hasTable(tablename: string): Promise<boolean> {
@@ -83,12 +85,10 @@ export class PostgresConnection implements RdbmsConnection {
   }
 
   private async init(): Promise<void> {
-    this.pool = new pg.Pool({
-      host: this.dbUrl.hostname,
-      user: decodeURIComponent(this.dbUrl.username),
-      password: decodeURIComponent(this.dbUrl.password),
-      database: this.getDatabase(),
-      port: Number(this.dbUrl.port),
-    });
+    const config = parse(this.connectionString);
+    if (config.database) {
+      config.database = decodeURIComponent(config.database);
+    }
+    this.pool = new pg.Pool(config as pg.PoolConfig);
   }
 }