feat: example proxying to multiple pglite dbs with persistence

.gitignore

@@ -1,4 +1,5 @@
-node_modules
-dist
+node_modules/
+dist/
+dbs/
 *.pem
 *.srl

examples/pglite-multiple/index.ts

@@ -0,0 +1,98 @@
+import { PGlite, PGliteInterface } from '@electric-sql/pglite';
+import { mkdir, readFile } from 'node:fs/promises';
+import net from 'node:net';
+import {
+  PostgresConnection,
+  TlsOptionsCallback,
+  hashMd5Password,
+} from '../../src';
+
+const tls: TlsOptionsCallback = async ({ sniServerName }) => {
+  // Optionally serve different certs based on `sniServerName`
+  // In this example we'll use a single wildcard cert for all servers (ie. *.db.example.com)
+  return {
+    key: await readFile('server-key.pem'),
+    cert: await readFile('server-cert.pem'),
+    ca: await readFile('ca-cert.pem'),
+  };
+};
+
+function getIdFromServerName(serverName: string) {
+  // In this example the left-most subdomain contains the ID
+  // ie. 12345.db.example.com -> 12345
+  const [id] = serverName.split('.');
+  return id;
+}
+
+const server = net.createServer((socket) => {
+  let db: PGliteInterface;
+
+  const connection = new PostgresConnection(socket, {
+    serverVersion: '16.3 (PGlite 0.2.0)',
+    authMode: 'md5Password',
+    tls,
+    async validateCredentials(credentials) {
+      if (credentials.authMode === 'md5Password') {
+        const { hash, salt } = credentials;
+        const expectedHash = await hashMd5Password(
+          'postgres',
+          'postgres',
+          salt
+        );
+        return hash === expectedHash;
+      }
+      return false;
+    },
+    onTlsUpgrade({ tlsInfo }) {
+      if (!tlsInfo) {
+        connection.sendError({
+          severity: 'FATAL',
+          code: '08000',
+          message: `ssl connection required`,
+        });
+        connection.socket.end();
+        return;
+      }
+
+      if (!tlsInfo.sniServerName) {
+        connection.sendError({
+          severity: 'FATAL',
+          code: '08000',
+          message: `ssl sni extension required`,
+        });
+        connection.socket.end();
+        return;
+      }
+
+      const databaseId = getIdFromServerName(tlsInfo.sniServerName);
+
+      db = new PGlite(`./dbs/${databaseId}`);
+    },
+    async onMessage(data, { isAuthenticated }) {
+      // Only forward messages to PGlite after authentication
+      if (!isAuthenticated) {
+        return false;
+      }
+
+      // Forward raw message to PGlite
+      try {
+        const [[_, responseData]] = await db.execProtocol(data);
+        connection.sendData(responseData);
+      } catch (err) {
+        connection.sendError(err);
+        connection.sendReadyForQuery();
+      }
+      return true;
+    },
+  });
+
+  socket.on('end', () => {
+    console.log('Client disconnected');
+  });
+});
+
+server.listen(5432, async () => {
+  console.log('Server listening on port 5432');
+
+  await mkdir('./dbs', { recursive: true });
+});