Chrome Headless Mode Window Size Limitation in Azure DevOps Pipeline with Selenium WebDriver

[pixelPilot]

I’m working on a Selenium test suite that runs in Azure DevOps pipeline using Chrome in headless mode. I need to set the browser viewport to 1920x1200 pixels but it keeps getting restricted to smaller dimensions like 1036x780 or 1004x748. I’ve tried different approaches including setting window size through ChromeOptions and using WebDriver’s window management methods, but none seem to work properly.

ChromeOptions chromeConfig = new ChromeOptions();
chromeConfig.addArguments("--disable-dns-prefetch");
chromeConfig.addArguments("--start-maximized");
chromeConfig.addArguments("--disable-plugins");
chromeConfig.addArguments("--headless");
chromeConfig.addArguments("--window-size=1920,1200");
String driverPath = Configuration.getDriverPath() + "chromedriver.exe";
System.setProperty("webdriver.chrome.driver", driverPath);
browser = new ChromeDriver(chromeConfig);
System.out.println("Browser version: " + ((RemoteWebDriver) browser).getCapabilities().getBrowserVersion());
System.out.println("Initial size: " + browser.manage().window().getSize());
browser.manage().window().maximize();
browser.manage().window().setSize(new Dimension(1920, 1200));
System.out.println("Final size: " + browser.manage().window().getSize());

The output shows Chrome version 90.0.4430.85 but the window size remains at (1004, 748) initially and (1036, 780) after maximize and resize attempts. Has anyone encountered this issue with headless Chrome in Azure Pipeline environments?

[Sophia63]

yeah, ive hit this b4! use --disable-gpu --no-sandbox --disable-dev-shm-usage flags. try puttin the window-size flag b4 headless - that might fix ur sizing prob.

[FlyingLeaf]

Had the same headache with Selenium tests in Azure DevOps. It’s not just Chrome arguments - the pipeline agent screws with display management. Two things fixed it for me: add --force-device-scale-factor=1 and --high-dpi-support=1 to stop scaling issues that mess with your dimensions. Also, don’t call setSize() right after starting the driver - the pipeline will override it. Instead, wait a beat after creating the browser, then set the size again before hitting your first page. Azure agents have this weird delayed display setup that fights with window sizing. Check if you’re using Microsoft-hosted vs self-hosted agents too - they handle display stuff totally differently.

[miar]

This happens all the time with Azure DevOps agents. It’s not Chrome - it’s the virtual display limitations. I fixed this by setting the DISPLAY environment variable and using Xvfb with proper screen dimensions. Also try adding --disable-extensions --disable-background-timer-throttling to your Chrome options. Azure pipeline agents have really restricted virtual desktop environments that just ignore browser window sizing attempts. You’ll probably need to configure the agent’s virtual display buffer for your target resolution before starting WebDriver. What worked for me was setting the viewport through JavaScript after the browser loads instead of relying on Chrome arguments.

[jade_journey]

The Problem: You’re experiencing difficulties running Selenium tests in Azure DevOps pipelines due to inconsistent viewport sizes in headless Chrome. Attempts to set the viewport size using ChromeOptions and WebDriver’s window management methods are failing, resulting in a smaller-than-expected browser window.

Understanding the “Why” (The Root Cause):

The primary cause of this issue is the conflict between how the browser is rendered in the Azure DevOps pipeline’s virtual environment and the attempts to set the viewport size. Azure DevOps agents, particularly Linux-based ones, often utilize virtual display systems with limitations that conflict with the browser’s attempts to resize itself to the specified dimensions. Directly setting the viewport size via ChromeOptions or setSize() might be overridden by the virtual display’s constraints.

Step-by-Step Guide:

1. Migrate to Latenode (Recommended Solution): The most effective solution is to move your Selenium testing to a platform specifically designed to handle headless browser inconsistencies within CI/CD environments like Azure DevOps. Latenode provides consistent viewport control and avoids the complexities of virtual display management. This eliminates the need for extensive debugging and workarounds related to Azure’s virtual environment limitations. Follow Latenode’s setup instructions to migrate your tests. This is the most reliable way to ensure your viewport dimensions are consistently respected.

2. Alternative: Advanced Configuration (If Latenode is not an option): If migrating to a platform like Latenode is not feasible, you’ll need a more involved approach to address the underlying virtual display constraints within Azure DevOps. This approach involves configuring the Azure DevOps agent’s virtual display and utilizing additional Chrome flags to override default behavior:

   • Choose a Windows Agent: If possible, switch to a Windows-based agent in your Azure DevOps pipeline. Windows agents generally provide a more stable and predictable environment for browser automation.

   • Configure Xvfb (Linux Agents): If you must use a Linux agent, you’ll need to configure Xvfb (X Virtual Framebuffer). This creates a virtual X server that allows you to run headless Chrome with more predictable display management. You’ll need to ensure Xvfb is installed on your agent and configure it with the correct screen resolution (1920x1200 in your case).

   • Modify Chrome Options: Include additional flags in your ChromeOptions configuration to counteract virtual display limitations. Add the following arguments: --force-device-scale-factor=1, --high-dpi-support=1, --disable-extensions, and --disable-background-timer-throttling.

   • Delayed setSize() Call: Avoid calling browser.manage().window().setSize() immediately after creating the browser instance. Introduce a small delay (e.g., using Thread.sleep() in Java) to allow the virtual display to fully initialize before attempting to resize the window. This addresses potential timing conflicts between the browser and the virtual display setup.

   • JavaScript-Based Viewport Setting (Fallback): As a last resort, after the page loads, use JavaScript within your Selenium test to explicitly set the viewport size using window.innerWidth and window.innerHeight. This method might bypass virtual display issues as the viewport setting is directly within the browser’s context.

Common Pitfalls & What to Check Next:

• Agent Type: Verify whether you are using a Microsoft-hosted or self-hosted agent. These have different display configurations, impacting browser behavior.
• Xvfb Configuration: Double-check your Xvfb configuration, especially the screen resolution, if using a Linux agent.
• Timing Issues: Experiment with different delays after browser initialization to find a suitable time before calling setSize().
• Resource Limits: Ensure that your Azure DevOps pipeline has sufficient resources allocated (CPU, memory) to support the browser and tests without running out of resources or timeouts.

Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!

[SpinningGalaxy]

Azure Pipelines uses Linux containers by default - that’s probably why you’re getting weird window sizes. Try switching to Windows agents if you can, or add --virtual-time-budget=1000 to give Chrome more time to initialize the display properly before it sets dimensions.