This is a docker container exposing a simple yet powerful API for quick websites rendering. Optimized for speed of rendering, in comparison to zitros/prerender.
docker pull zitros/webrender
- Always production-ready and as light as possible.
- Get any data from rendered pages with arbitrary async JavaScript.
- Render PDF snapshots of the webpage or assemble your own with JavaScript.
- Using Playwright with Chromium under the hood.
This container exposes its API on port 8080. Example: http://this-container:8080/health-check.
- Request body type (for POST requests):
application/json - Response body type (for all endpoints):
application/json
Endpoint for checking whether this container is healthy. It will render a dummy page served on localhost
under the hood and return status 200 when all right.
Renders the page as if it was opened in Chrome browser, optionally invoking custom async JavaScript
provided as a "js" parameter.
- A result of a custom async JavaScript invocation (
"js"and"jsOn"parameters) is returned in the response as"result". - A result of the PDF generation (
"takePdfSnapshot"parameter) is returned in the response as"pdfSnapshot".
Request body:
{
/** REQUIRED. URL of the page to render. Empty string means "blank" page. */
"url": "https://www.google.com/search?q=cats&tbm=isch",
/** OPTIONAL. Timeout for the rendering task. Defaults to 20 seconds. */
"timeout": 20000,
/** OPTIONAL. When specified, also returns a base64-encoded "pdfSnapshot" property in the response. */
"takePdfSnapshot": true,
/**
* OPTIONAL. You can specify when to run a JS snippet, if given.
*
* - "commit" (default) => before the page is even created (init script)
* - "domcontentloaded" => after the html document was parsed
* - "load" => after the page contents is fully loaded, including async scripts
*/
"jsOn": "commit",
/**
* OPTIONAL. An arbitrary JavaScript code to be invoked in ASYNC CONTEXT in the browser, immediately
* when page starts loading. Once this code returns, WebRender will immediately close the page and
* return the result which is equal to a serializable value of what was returned.
*/
"js": ` // This code is specified as a template string for this example readability. It should use standard JSON notation.
let firstCat;
while (true) {
if (firstCat = document.querySelector('div[jsaction] div[jsaction] img')) {
return { cat: firstCat.src }; // As soon as this code returns, /render will respond with the result.
}
await new Promise(resolve => setTimeout(resolve, 50)); // Sleep for 50ms
}
`,
/**
* OPTIONAL. Extra headers to send with browser requests.
* @see https://playwright.dev/docs/api/class-browsercontext#browser-context-set-extra-http-headers
*/
"extraHttpHeaders": {
"Authorization": "Bearer EXAMPLE==="
}
}In request's "js", you can use the following utility functions in the global context:
/**
* Allows to wait until the network becomes idle. Handy to determine when the page is fully loaded. Mind that some pages can do infinite http polling.
* Resolves when there are no more pending network requests within idleTimeout, but resolveBeforeRenderingTimeout before the global timeout.
*/
const { isTimeout } = await webrender.pendingRequests({
/** OPTIONAL. Number of milliseconds to wait between network requests. Defaults to 2000. */
idleTimeout: 2000,
/** OPTIONAL. Number of milliseconds to resolve before the rendering timeout. Defaults to 2000. */
resolveBeforeRenderingTimeout: 2000,
});
// `isTimeout` equals to true if the waiting time was a timeout.Response body example when request succeeds:
{
/* Requested URL. */
"url": "https://www.google.com/search?q=cats&tbm=isch",
/* JavaScript evaluation result (stringified object - the returned type is up to you). */
"result": {
"cat": "data:image/jpeg;base64,/9j/4AAQSkZ...yiFQ2pa4tNPQitOFX//Z"
},
/* Optional BASE64-encoded PDF, when "takePdfSnapshot" is given. */
"pdfSnapshot": "Aci2zo...S51==",
}Response body when request fails:
{
/** Error message. Always defined in error responses. */
"error": "page.evaluate: Evaluation failed: ReferenceError: windo is not defined\n at eval (eval at <anonymous> (eval at evaluate (:303:29)), <anonymous>:3:41)\n at eval (eval at evaluate (:303:29), <anonymous>:9:30)",
/**
* Error code. Always defined in error responses.
*
* - BAD_REQUEST => Invalid request.
* - TIMEOUT => Render request timeout (the desired result is not obtained within timeout).
* - NAVIGATION => Navigation errors, such as malformed URL, DNS or TLS certificate errors.
* - JS => A JavaScript error occurred (in the provided "js").
* - UNKNOWN => Unpredicted errors which means that webrender has failed.
*/
"errorCode": "JS", // See error codes below.
/** Always the requested URL. */
"url": "https://www.google.com/search?q=cats&tbm=isch",
/** Always null */
"result": null,
}