scrapy-crawlera 1.5 documentation¶

scrapy-crawlera is a Scrapy Downloader Middleware to interact with Crawlera automatically.

Configuration¶

Add the Crawlera middleware including it into the DOWNLOADER_MIDDLEWARES in your settings.py file:

DOWNLOADER_MIDDLEWARES = {
    ...
    'scrapy_crawlera.CrawleraMiddleware': 610
}

Then there are two ways to enable it

Through settings.py:

CRAWLERA_ENABLED = True
CRAWLERA_APIKEY = 'apikey'

Through spider attributes:

class MySpider:
    crawlera_enabled = True
    crawlera_apikey = 'apikey'

(optional) If you are not using the default Crawlera proxy (http://proxy.crawlera.com:8010), for example if you have a dedicated or private instance, make sure to also set CRAWLERA_URL in settings.py, e.g.:
```
CRAWLERA_URL = 'http://myinstance.crawlera.com:8010'
```

How to use it¶

Settings¶

This Middleware adds some settings to configure how to work with Crawlera.

CRAWLERA_APIKEY¶

Default: None

Unique Crawlera API Key provided for authentication.

CRAWLERA_URL¶

Default: 'http://proxy.crawlera.com:8010'

Crawlera instance url, it varies depending on adquiring a private or dedicated instance. If Crawlera didn’t provide you with a private instance url, you don’t need to specify it.

CRAWLERA_MAXBANS¶

Default: 400

Number of consecutive bans from Crawlera necessary to stop the spider.

CRAWLERA_DOWNLOAD_TIMEOUT¶

Default: 190

Timeout for processing Crawlera requests. It overrides Scrapy’s DOWNLOAD_TIMEOUT.

CRAWLERA_PRESERVE_DELAY¶

Default: False

If False Sets Scrapy’s DOWNLOAD_DELAY to 0, making the spider to crawl faster. If set to True, it will respect the provided DOWNLOAD_DELAY from Scrapy.

CRAWLERA_DEFAULT_HEADERS¶

Default: {}

Default headers added only to crawlera requests. Headers defined on DEFAULT_REQUEST_HEADERS will take precedence as long as the CrawleraMiddleware is placed after the DefaultHeadersMiddleware. Headers set on the requests have precedence over the two settings.

This is the default behavior, DefaultHeadersMiddleware default priority is 400 and we recommend CrawleraMiddleware priority to be 610

CRAWLERA_BACKOFF_STEP¶

Default: 15

Step size used for calculating exponential backoff according to the formula: random.uniform(0, min(max, step * 2 ** attempt)).

CRAWLERA_BACKOFF_MAX¶

Default: 180

Max value for exponential backoff as showed in the formula above.

Settings: All configurable Scrapy Settings added by the Middleware.

With the middleware, the usage of crawlera is automatic, every request will go through crawlera without nothing to worry about. If you want to disable crawlera on a specific Request, you can do so by updating meta with dont_proxy=True:

scrapy.Request(
    'http://example.com',
    meta={
        'dont_proxy': True,
        ...
    },
)

Remember that you are now making requests to Crawlera, and the Crawlera service will be the one actually making the requests to the different sites.

If you need to specify special Crawlera Headers, just apply them as normal Scrapy Headers.

Here we have an example of specifying a Crawlera header into a Scrapy request:

scrapy.Request(
    'http://example.com',
    headers={
        'X-Crawlera-Max-Retries': 1,
        ...
    },
)

Remember that you could also set which headers to use by default by all requests with DEFAULT_REQUEST_HEADERS

Note

Crawlera headers are removed from requests when the middleware is activated but Crawlera is disabled. For example, if you accidentally disable Crawlera via crawlera_enabled = False but keep sending X-Crawlera-* headers in your requests, those will be removed from the request headers.

This Middleware also adds some configurable Scrapy Settings, check the complete list here.

All the rest¶

Changes¶

v1.5.1 (2019-05-21)¶

Remove username and password from settings since it’s removed from crawlera.
Include affected spider in logs.
Handle situations when crawlera is restarted and reply with 407’s for a few minutes by retrying the requests with a exponential backoff system.

v1.5.0 (2019-01-23)¶

Correctly check for bans in crawlera (Jobs will not get banned on non ban 503’s).
Exponential backoff when crawlera doesn’t have proxies available.
Fix dont_proxy=False header disabling crawlera when it is enabled.

v1.4.0 (2018-09-20)¶

Remove X-Crawlera-* headers when Crawlera is disabled.
Introduction of DEFAULT_CRAWLERA_HEADERS settings.

v1.3.0 (2018-01-10)¶

Use CONNECT method to contact Crawlera proxy.

v1.2.4 (2017-07-04)¶

Trigger PYPI deployments after changes made to TOXENV in v1.2.3

v1.2.3 (2017-06-29)¶

Multiple documentation fixes
Test scrapy-crawlera on combinations of software used by scrapinghub stacks

v1.2.2 (2017-01-19)¶

Fix Crawlera error stats key in Python 3.
Add support for Python 3.6.

v1.2.1 (2016-10-17)¶

Fix release date in README.

v1.2.0 (2016-10-17)¶

Recommend middleware order to be 610 to run before RedirectMiddleware.
Change default download timeout to 190s or 3 minutes 10 seconds (instead of 1800s or 30 minutes).
Test and advertize Python 3 compatiblity.
New crawlera/request and crawlera/request/method/* stats counts.
Clear Scrapy DNS cache for proxy URL in case of connection errors.
Distribute plugin as universal wheel.

Changes: See what has changed in recent scrapy-crawlera versions.