Playwright Java over CDP: Set a Proxy on a New Browser Context

A remote browser has two network paths: Java's control connection to the browser service, and the browser's requests to websites. Configure the latter on the context you create.

For a Chromium service exposing a CDP endpoint and allowing new contexts:

import com.microsoft.playwright.*;
import com.microsoft.playwright.options.Proxy;

try (Playwright playwright = Playwright.create()) {
    Browser browser = playwright.chromium().connectOverCDP(cdpEndpoint);
    try {
        var options = new Browser.NewContextOptions().setProxy(
            new Proxy("http://proxy.example:8080")
                .setUsername(proxyUser)
                .setPassword(proxyPassword));
        try (BrowserContext context = browser.newContext(options)) {
            context.newPage().navigate("https://www.example.org/");
        }
    } finally {
        browser.close();
    }
}

cdpEndpoint is the current endpoint supplied by the browser service. Its authentication token and protocol are independent of the forward proxy account.

CDP connections are Chromium-only. A Playwright-protocol endpoint uses connect instead; changing a URL suffix without checking the service's protocol is not a reliable conversion.

The proxy must be reachable from the remote browser's host. A loopback listener on the Java machine is not automatically available there. The new context's setting also does not reconfigure an already existing default context or Java's WebSocket connection.