allow changing port and host via options and env

README.md

@@ -185,18 +185,30 @@ Run agents in isolated environments (devcontainers, VMs, SSH) while controlling
 
 ```bash
 npx playwriter serve --token <secret>
+# or use environment variable:
+PLAYWRITER_TOKEN=<secret> npx playwriter serve
 ```
 
 **In container/VM (where agent runs):**
 
+Using environment variables:
+
 ```bash
-export PLAYWRITER_URL="ws://host.docker.internal:19988?token=<secret>"
+export PLAYWRITER_HOST="host.docker.internal"
+export PLAYWRITER_TOKEN="<secret>"
+```
+
+Or using CLI options:
+
+```bash
+npx playwriter --host host.docker.internal --token <secret>
 ```
 
 Use `host.docker.internal` for devcontainers, or your host's IP for VMs/SSH.
 
 ## Known Issues
 
+- **Do not use `bunx` to run the MCP.** Bun has incomplete support for the `ws` library's WebSocket events, which breaks playwright-core's CDP connection. Use `npx` instead. See bun issues: [#5951](https://github.com/oven-sh/bun/issues/5951), [#9911](https://github.com/oven-sh/bun/issues/9911)
 - If all pages urls return `about:blank` in every MCP session restart your Chrome browser. This seems to be a Chrome bug that sometimes happen. It is some hidden state in `chrome.debugger` Extensions API. Restarting the extension worker does not fix it. 
 - When connecting the MCP to a page, the browser may switch to light mode. This happens because Playwright, via CDP, automatically sends an "emulate media" command on start. If you'd like to see this behavior changed, you can upvote the related issue [here](https://github.com/microsoft/playwright/issues/37627).
 

playwriter/src/cli.ts

@@ -11,16 +11,28 @@ const cli = cac('playwriter')
 
 cli
   .command('', 'Start the MCP server (default)')
-  .action(async () => {
+  .option('--host <host>', 'Remote relay server host to connect to (or use PLAYWRITER_HOST env var)')
+  .option('--token <token>', 'Authentication token (or use PLAYWRITER_TOKEN env var)')
+  .action(async (options: { host?: string; token?: string }) => {
     const { startMcp } = await import('./mcp.js')
-    await startMcp()
+    await startMcp({
+      host: options.host,
+      token: options.token,
+    })
   })
 
 cli
   .command('serve', 'Start the CDP relay server for remote MCP connections')
   .option('--host <host>', 'Host to bind to', { default: '0.0.0.0' })
-  .option('--token <token>', 'Authentication token for /cdp/* endpoints')
+  .option('--token <token>', 'Authentication token (or use PLAYWRITER_TOKEN env var)')
   .action(async (options: { host: string; token?: string }) => {
+    const token = options.token || process.env.PLAYWRITER_TOKEN
+    if (!token) {
+      console.error('Error: Authentication token is required.')
+      console.error('Provide --token <token> or set PLAYWRITER_TOKEN environment variable.')
+      process.exit(1)
+    }
+
     const logger = createFileLogger()
 
     process.title = 'playwriter-serve'
@@ -38,19 +50,19 @@ cli
     const server = await startPlayWriterCDPRelayServer({
       port: RELAY_PORT,
       host: options.host,
-      token: options.token,
+      token,
       logger,
     })
 
     console.log('Playwriter CDP relay server started')
     console.log(`  Host: ${options.host}`)
     console.log(`  Port: ${RELAY_PORT}`)
-    console.log(`  Token: ${options.token ? '(configured)' : '(none)'}`)
+    console.log(`  Token: (configured)`)
     console.log(`  Logs: ${logger.logFilePath}`)
     console.log('')
     console.log('Endpoints:')
     console.log(`  Extension: ws://${options.host}:${RELAY_PORT}/extension`)
-    console.log(`  CDP:       ws://${options.host}:${RELAY_PORT}/cdp/<client-id>${options.token ? '?token=<token>' : ''}`)
+    console.log(`  CDP:       ws://${options.host}:${RELAY_PORT}/cdp/<client-id>?token=<token>`)
     console.log('')
     console.log('Press Ctrl+C to stop.')