Why does Playwright's browserContext.newPage fail in a Docker container but succeed outside?

Below is a list of suggestions to diagnose and possibly correct the issue. Note that many Playwright and browser crashes in containerized environments are related to system-level dependencies, sandboxing, or architecture mismatches.

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1. Verify Architecture Compatibility

Since you’re using an M2 Macintosh with Colima, you’re likely building an amd64 image for compatibility. Make sure that when you specify the platform (with --platform=linux/amd64), all native binaries are built for the correct architecture. If any part of your chain (for example, the base image or dependencies) is not compatible with AMD64 emulation on an ARM host, you may run into issues. Consider the following:

• Rebuild your images using the --platform linux/amd64 flag.
• Look into multi-platform image builds (using Docker buildx) so that you have native arm64 images available where possible.

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2. Adjust Browser Sandbox Settings

Many browser engines require modifications in container environments. A common solution for containerized browsers (especially Chromium) is to disable the sandbox or tweak sandbox flags. For example, when launching Chrome or Chromium in a container, using the flag --no-sandbox is often required:

JSCopied
const browser = await playwright.chromium.launch({
  args: ['--no-sandbox', '--disable-setuid-sandbox']
});

If Testaro (or its Playwright subdependency) allows you to pass additional browser arguments, try adding those sandbox disabling flags. Similar considerations can apply to other browser types if they run in a sandbox context.

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3. Install Missing Dependencies

The error message from Chromium also suggests that the container cannot connect to the system bus (no /run/dbus/system_bus_socket). Modern browser container images (like the ones from Microsoft’s Playwright image) usually have the required dependencies installed. However, if you’re layering on top of another image (your custom champ-testaro image), verify that nothing is removing the required libraries and that all the dependencies needed by each browser (and their automation tools) are present.

For instance, if your container is based on Ubuntu (Jammy), compare it with the official Playwright image to ensure all required system libraries are installed.

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4. Consider Running in Privileged Mode (or Adjusting Security Options)

Since the error messages hint at permission-related issues (e.g., “automation is not allowed in the context”), try running the container with additional capabilities or in privileged mode to check if security restrictions are causing the crash. For example:

BASHCopied
docker run --rm --platform=linux/amd64 --cap-add=SYS_ADMIN -p 3000:3000 champ-testaro

While this is typically not recommended for production, it can help diagnose whether additional security restrictions are at play.

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5. Log and Compare Environment Differences

When the application runs outside a container it works fine. Inside the container, inspect and compare:

• Environment variables (especially those related to Playwright or Node.js)
• File system mounts and working directories (ensure that you’re not missing any linked files or folders)
• Permissions and the user executing the process (your Dockerfiles set --chown="nonroot:nonroot", so verify that the non-root user has sufficient privileges to launch browsers)

You can add debugging logs (or try an interactive shell inside the running container) to compare these parameters.

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Summary

• Architecture: Ensure that you’re building images for the correct platform and consider multi-arch builds.
• Browser Args: Disable sandboxing with flags like --no-sandbox and --disable-setuid-sandbox.
• Dependencies: Validate that all the system dependencies and libraries required for each browser are present.
• Security: Experiment with additional privileges to see if security restrictions are causing sandbox or DBus issues.
• Environment: Compare the runtime environment (user permissions, environment variables, file mounts) between your non-containerized and containerized runs.

These steps should help you narrow down the cause and apply the appropriate fix for the Playwright crash in your containerized Node.js application.