magelan/docker-screenshot repository overview

⁠docker-screenshot

A container that expose a HTTP endpoint to take screenshot of a webpage. It use a puppeteer with the maximum Web GL capabilities that is possible inside a container.

⁠How to make a screenshot

In fact this container does not take the screenshot for you... It listen for a custom DOM event called screenshotTaken that contain the actual screenshot.

The opened web page have:

1. Generate an image (a screenshot or whatever else)
2. Encode it in a valid data URI⁠
3. Trigger a DOM CustomEvent that contain the data URI

⁠screenshotTaken custom event

const screenshotDataURI = 'data:image/png;base64,...'

document.dispatchEvent(
  new CustomEvent('screenshotTaken', {
    detail: {
      dataURI: screenshotDataURI,
    },
  }),
)

⁠API

⁠GET /screenshot

Parameter:

• target (string): the web page to open

Load the web page given in the target parameter and return the screenshot contained in the screenshotTaken event of the target page (see the How to make a screenshot section for a detailed explanation). To respect the URL format the target parameter should be URL encoded.

Eg:

GET /screenshot?target=https%3A%2F%2Fplayground.babylonjs.com%2F%23FZTP31%231

The target page have 60 seconds to return the screenshotTaken event. The endpoint will return an error 500 after 60 seconds.

⁠GET /capabilities/webgl.html

Only available in debug mode

Expose the https://alteredqualia.com/tools/webgl-features/⁠ webgl features detection page from inside the container.

⁠GET /health

Check the container status. Return a 200 HTTP status if everythings is ok.

⁠Environment variables

• DEBUG (boolean): Increase the log outputed by the container (false by default)
• SENTRY_DSN (string): The sentry.io⁠ error reporting DSN (optional)