prerender

Render JavaScript-rendered page as HTML/PDF/mhtml/png/jpeg using headless Chrome

Install Chrome

Headless mode is supported in Chrome stable 59+ and unstable/dev channel, you should be able to install it via:

https://www.google.com/chrome/browser/beta.html?platform=linux

Start Chrome Headless

$ google-chrome --headless --remote-debugging-port=9222 --disable-gpu "about:blank"

To disable image loading, add --blink-settings=imagesEnabled=false argument:

$ google-chrome --headless --remote-debugging-port=9222 --disable-gpu --blink-settings=imagesEnabled=false "about:blank"

Install Prerender

$ pip install -U prerender

Start Prerender

As standalone application:

$ prerender

To run it under gunicorn:

$ gunicorn --bind 0.0.0.0:3000 --worker-class sanic.worker.GunicornWorker prerender.app:app

How does it work

Say you deployed Prerender under http://prerender.example.com:8000, to render http://example.com you can do:

$ # render HTML
$ curl http://prerender.example.com:8000/http://example.com
$ curl http://prerender.example.com:8000/html/http://example.com
$ # render mhtml
$ curl http://prerender.example.com:8000/mhtml/http://example.com
$ # render PDF
$ curl http://prerender.example.com:8000/pdf/http://example.com
$ # render png
$ curl http://prerender.example.com:8000/png/http://example.com
$ # render jpeg
$ curl http://prerender.example.com:8000/jpeg/http://example.com

Configuration

Settings are mostly configured by environment variables.

ENV	default value	description
HOST	0.0.0.0	Prerender listen host
PORT	8000	Prerender listen port
DEBUG	false	Toggle debug mode
PRERENDER_TIMEOUT	30	renderring timeout
PAGE_DONE_CHECK_TIMEOUT	200	Number of milliseconds between the interval of checking whether the page is done loading or not
CONCURRENCY	2 * CPU count	Chrome pages count
MAX_ITERATIONS	200	Restart Chrome page after rendering this many pages
CHROME_HOST	localhost	Chrome remote debugging host
CHROME_PORT	9222	Chrome remote debugging port
USER_AGENT		Chrome User Agent
BLOCK_FONTS	1	Block web fonts loading, set to 0 to allow fonts loading
ALLOWED_DOMAINS		Domains allowed for renderring, comma seperated
CACHE_BACKEND	dummy	Cache backend, dummy, disk, s3
CACHE_LIVE_TIME	3600	Disk cache live seconds
CACHE_ROOT_DIR	/tmp/prerender	Disk cache root directory
S3_SERVER	s3.amazonaws.com	S3 server address
S3_ACCESS_KEY		S3 access key
S3_SECRET_KEY		S3 secret key
S3_REGION		S3 region
S3_BUCKET	prerender	S3 bucket name
SENTRY_DSN		Sentry DSN, for exception monitoring
ENABLE_CIRCUIT_BREAKER	false	enable circuit breaker
CIRCUIT_BREAKER_FAIL_MAX	5	maximum failures per browser/bot before circuit breaker open
CIRCUIT_BREAKER_RESET_TIMEOUT	60	circuit breaker reset timeout in seconds

Configure client

Please view the original NodeJs version prerender README.

License

MIT