DeckTape

DeckTape can be executed using the ghcr.io/astefanutti/decktape container image. This is useful for environments where you don't want to install Node.js or Puppeteer locally.

Convert an online presentation to a local PDF: Mount the current working directory to /slides inside the container so the output is written to your host filesystem.

$ docker run --rm -t -v `pwd`:/slides ghcr.io/astefanutti/decktape https://revealjs.com/demo/ slides.pdf

Convert a local HTML file: Mount both your current directory and the directory containing your slides.

$ docker run --rm -t -v `pwd`:/slides -v ~:/home/user ghcr.io/astefanutti/decktape /home/user/slides.html slides.pdf

Convert a presentation on localhost: Use --net=host to allow the container to access your host's network. Note that on macOS and Windows, you may need to use host.docker.internal instead of localhost.

$ docker run --rm -t --net=host -v `pwd`:/slides ghcr.io/astefanutti/decktape http://localhost:8000 slides.pdf

No usable sandbox!

If you encounter sandbox errors (common on Arch Linux), pass the --no-sandbox flag to Chrome:

$ decktape ... --chrome-arg=--no-sandbox

Mixed Content Errors

If the page is HTTPS but requests insecure resources, allow insecure content:

$ decktape ... --chrome-arg=--allow-running-insecure-content

CORS / CSS Access Errors

If you see Failed to read the 'rules' property from 'CSSStyleSheet', you may need to disable web security to allow access to local/external stylesheets:

$ decktape ... --chrome-arg=--disable-web-security

Layout Inconsistencies

If the layout looks wrong, try setting a specific viewport size using the -s option:

$ decktape -s 1024x768 <url> <filename>

Reveal.js specific note

Do not append ?print-pdf to the URL or load print stylesheets when using DeckTape with Reveal.js, as DeckTape captures slides individually.

The playwright.config.ts file defines the execution environment for DeckTape's Playwright-based tests. Key configuration areas include:

• Test Execution: Sets the testDir to ./test, a global timeout of 30 seconds, and enables fullyParallel execution.
• Assertions: The expect.timeout is set to 5000ms, which is the maximum time expect() calls will wait for conditions to be met.
• CI Environment: When running in a CI environment (process.env.CI is truthy), the configuration automatically enables forbidOnly, sets retries to 2, and limits workers to 1 to prevent parallelization issues.
• Reporting: Uses the html reporter to generate test results.
• Web Server: Automatically starts a local development server using node test/run-server.js ${port} before running tests, reusing the existing server if it is already running.

const config: PlaywrightTestConfig = {
  testDir: './test',
  timeout: 30 * 1000,
  expect: {
    timeout: 5000
  },
  fullyParallel: true,
  forbidOnly: !!process.env.CI,
  retries: process.env.CI ? 2 : 0,
  workers: process.env.CI ? 1 : undefined,
  reporter: 'html',
  use: {
    actionTimeout: 0,
    trace: 'on-first-retry',
    baseURL: `http://localhost:${port}`
  },
  projects: [
    {
      name: 'firefox',
      use: devices['Desktop Firefox'],
    }
  ],
  webServer: {
    command: `node test/run-server.js ${port}`,
    port,
    reuseExistingServer: true,
  },
};

General options available for most commands: