prerender 0.9.2

# 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

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

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

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

## Install Prerender

```bash
$ pip install -U prerender
```

## Start Prerender

As standalone application:

```bash
$ prerender
```

To run it under gunicorn:

```bash
$ 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:

```bash
$ # 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](https://github.com/prerender/prerender#official-middleware) README.

## License

MIT