.. _topics-settings: ======== Settings ======== The Scrapy settings allows you to customize the behaviour of all Scrapy components, including the core, extensions, pipelines and spiders themselves. The infrastructure of the settings provides a global namespace of key-value mappings that the code can use to pull configuration values from. The settings can be populated through different mechanisms, which are described below. The settings are also the mechanism for selecting the currently active Scrapy project (in case you have many). For a list of available built-in settings see: :ref:`topics-settings-ref`. .. _topics-settings-module-envvar: Designating the settings ======================== When you use Scrapy, you have to tell it which settings you're using. You can do this by using an environment variable, ``SCRAPY_SETTINGS_MODULE``. The value of ``SCRAPY_SETTINGS_MODULE`` should be in Python path syntax, e.g. ``myproject.settings``. Note that the settings module should be on the Python `import search path`_. .. _import search path: https://docs.python.org/2/tutorial/modules.html#the-module-search-path Populating the settings ======================= Settings can be populated using different mechanisms, each of which having a different precedence. Here is the list of them in decreasing order of precedence: 1. Command line options (most precedence) 2. Settings per-spider 3. Project settings module 4. Default settings per-command 5. Default global settings (less precedence) The population of these settings sources is taken care of internally, but a manual handling is possible using API calls. See the :ref:`topics-api-settings` topic for reference. These mechanisms are described in more detail below. 1. Command line options ----------------------- Arguments provided by the command line are the ones that take most precedence, overriding any other options. You can explicitly override one (or more) settings using the ``-s`` (or ``--set``) command line option. .. highlight:: sh Example:: scrapy crawl myspider -s LOG_FILE=scrapy.log 2. Settings per-spider ---------------------- Spiders (See the :ref:`topics-spiders` chapter for reference) can define their own settings that will take precedence and override the project ones. They can do so by setting their :attr:`~scrapy.spiders.Spider.custom_settings` attribute:: class MySpider(scrapy.Spider): name = 'myspider' custom_settings = { 'SOME_SETTING': 'some value', } 3. Project settings module -------------------------- The project settings module is the standard configuration file for your Scrapy project, it's where most of your custom settings will be populated. For a standard Scrapy project, this means you'll be adding or changing the settings in the ``settings.py`` file created for your project. 4. Default settings per-command ------------------------------- Each :doc:`Scrapy tool ` command can have its own default settings, which override the global default settings. Those custom command settings are specified in the ``default_settings`` attribute of the command class. 5. Default global settings -------------------------- The global defaults are located in the ``scrapy.settings.default_settings`` module and documented in the :ref:`topics-settings-ref` section. How to access settings ====================== .. highlight:: python In a spider, the settings are available through ``self.settings``:: class MySpider(scrapy.Spider): name = 'myspider' start_urls = ['http://example.com'] def parse(self, response): print("Existing settings: %s" % self.settings.attributes.keys()) .. note:: The ``settings`` attribute is set in the base Spider class after the spider is initialized. If you want to use the settings before the initialization (e.g., in your spider's ``__init__()`` method), you'll need to override the :meth:`~scrapy.spiders.Spider.from_crawler` method. Settings can be accessed through the :attr:`scrapy.crawler.Crawler.settings` attribute of the Crawler that is passed to ``from_crawler`` method in extensions, middlewares and item pipelines:: class MyExtension(object): def __init__(self, log_is_enabled=False): if log_is_enabled: print("log is enabled!") @classmethod def from_crawler(cls, crawler): settings = crawler.settings return cls(settings.getbool('LOG_ENABLED')) The settings object can be used like a dict (e.g., ``settings['LOG_ENABLED']``), but it's usually preferred to extract the setting in the format you need it to avoid type errors, using one of the methods provided by the :class:`~scrapy.settings.Settings` API. Rationale for setting names =========================== Setting names are usually prefixed with the component that they configure. For example, proper setting names for a fictional robots.txt extension would be ``ROBOTSTXT_ENABLED``, ``ROBOTSTXT_OBEY``, ``ROBOTSTXT_CACHEDIR``, etc. .. _topics-settings-ref: Built-in settings reference =========================== Here's a list of all available Scrapy settings, in alphabetical order, along with their default values and the scope where they apply. The scope, where available, shows where the setting is being used, if it's tied to any particular component. In that case the module of that component will be shown, typically an extension, middleware or pipeline. It also means that the component must be enabled in order for the setting to have any effect. .. setting:: AWS_ACCESS_KEY_ID AWS_ACCESS_KEY_ID ----------------- Default: ``None`` The AWS access key used by code that requires access to `Amazon Web services`_, such as the :ref:`S3 feed storage backend `. .. setting:: AWS_SECRET_ACCESS_KEY AWS_SECRET_ACCESS_KEY --------------------- Default: ``None`` The AWS secret key used by code that requires access to `Amazon Web services`_, such as the :ref:`S3 feed storage backend `. .. setting:: BOT_NAME BOT_NAME -------- Default: ``'scrapybot'`` The name of the bot implemented by this Scrapy project (also known as the project name). This will be used to construct the User-Agent by default, and also for logging. It's automatically populated with your project name when you create your project with the :command:`startproject` command. .. setting:: CONCURRENT_ITEMS CONCURRENT_ITEMS ---------------- Default: ``100`` Maximum number of concurrent items (per response) to process in parallel in the Item Processor (also known as the :ref:`Item Pipeline `). .. setting:: CONCURRENT_REQUESTS CONCURRENT_REQUESTS ------------------- Default: ``16`` The maximum number of concurrent (ie. simultaneous) requests that will be performed by the Scrapy downloader. .. setting:: CONCURRENT_REQUESTS_PER_DOMAIN CONCURRENT_REQUESTS_PER_DOMAIN ------------------------------ Default: ``8`` The maximum number of concurrent (ie. simultaneous) requests that will be performed to any single domain. See also: :ref:`topics-autothrottle` and its :setting:`AUTOTHROTTLE_TARGET_CONCURRENCY` option. .. setting:: CONCURRENT_REQUESTS_PER_IP CONCURRENT_REQUESTS_PER_IP -------------------------- Default: ``0`` The maximum number of concurrent (ie. simultaneous) requests that will be performed to any single IP. If non-zero, the :setting:`CONCURRENT_REQUESTS_PER_DOMAIN` setting is ignored, and this one is used instead. In other words, concurrency limits will be applied per IP, not per domain. This setting also affects :setting:`DOWNLOAD_DELAY` and :ref:`topics-autothrottle`: if :setting:`CONCURRENT_REQUESTS_PER_IP` is non-zero, download delay is enforced per IP, not per domain. .. setting:: DEFAULT_ITEM_CLASS DEFAULT_ITEM_CLASS ------------------ Default: ``'scrapy.item.Item'`` The default class that will be used for instantiating items in the :ref:`the Scrapy shell `. .. setting:: DEFAULT_REQUEST_HEADERS DEFAULT_REQUEST_HEADERS ----------------------- Default:: { 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8', 'Accept-Language': 'en', } The default headers used for Scrapy HTTP Requests. They're populated in the :class:`~scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware`. .. setting:: DEPTH_LIMIT DEPTH_LIMIT ----------- Default: ``0`` Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware`` The maximum depth that will be allowed to crawl for any site. If zero, no limit will be imposed. .. setting:: DEPTH_PRIORITY DEPTH_PRIORITY -------------- Default: ``0`` Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware`` An integer that is used to adjust the request priority based on its depth: - if zero (default), no priority adjustment is made from depth - **a positive value will decrease the priority, i.e. higher depth requests will be processed later** ; this is commonly used when doing breadth-first crawls (BFO) - a negative value will increase priority, i.e., higher depth requests will be processed sooner (DFO) See also: :ref:`faq-bfo-dfo` about tuning Scrapy for BFO or DFO. .. note:: This setting adjusts priority **in the opposite way** compared to other priority settings :setting:`REDIRECT_PRIORITY_ADJUST` and :setting:`RETRY_PRIORITY_ADJUST`. .. setting:: DEPTH_STATS DEPTH_STATS ----------- Default: ``True`` Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware`` Whether to collect maximum depth stats. .. setting:: DEPTH_STATS_VERBOSE DEPTH_STATS_VERBOSE ------------------- Default: ``False`` Scope: ``scrapy.spidermiddlewares.depth.DepthMiddleware`` Whether to collect verbose depth stats. If this is enabled, the number of requests for each depth is collected in the stats. .. setting:: DNSCACHE_ENABLED DNSCACHE_ENABLED ---------------- Default: ``True`` Whether to enable DNS in-memory cache. .. setting:: DNSCACHE_SIZE DNSCACHE_SIZE ------------- Default: ``10000`` DNS in-memory cache size. .. setting:: DNS_TIMEOUT DNS_TIMEOUT ----------- Default: ``60`` Timeout for processing of DNS queries in seconds. Float is supported. .. setting:: DOWNLOADER DOWNLOADER ---------- Default: ``'scrapy.core.downloader.Downloader'`` The downloader to use for crawling. .. setting:: DOWNLOADER_HTTPCLIENTFACTORY DOWNLOADER_HTTPCLIENTFACTORY ---------------------------- Default: ``'scrapy.core.downloader.webclient.ScrapyHTTPClientFactory'`` Defines a Twisted ``protocol.ClientFactory`` class to use for HTTP/1.0 connections (for ``HTTP10DownloadHandler``). .. note:: HTTP/1.0 is rarely used nowadays so you can safely ignore this setting, unless you use Twisted<11.1, or if you really want to use HTTP/1.0 and override :setting:`DOWNLOAD_HANDLERS_BASE` for ``http(s)`` scheme accordingly, i.e. to ``'scrapy.core.downloader.handlers.http.HTTP10DownloadHandler'``. .. setting:: DOWNLOADER_CLIENTCONTEXTFACTORY DOWNLOADER_CLIENTCONTEXTFACTORY ------------------------------- Default: ``'scrapy.core.downloader.contextfactory.ScrapyClientContextFactory'`` Represents the classpath to the ContextFactory to use. Here, "ContextFactory" is a Twisted term for SSL/TLS contexts, defining the TLS/SSL protocol version to use, whether to do certificate verification, or even enable client-side authentication (and various other things). .. note:: Scrapy default context factory **does NOT perform remote server certificate verification**. This is usually fine for web scraping. If you do need remote server certificate verification enabled, Scrapy also has another context factory class that you can set, ``'scrapy.core.downloader.contextfactory.BrowserLikeContextFactory'``, which uses the platform's certificates to validate remote endpoints. **This is only available if you use Twisted>=14.0.** If you do use a custom ContextFactory, make sure it accepts a ``method`` parameter at init (this is the ``OpenSSL.SSL`` method mapping :setting:`DOWNLOADER_CLIENT_TLS_METHOD`). .. setting:: DOWNLOADER_CLIENT_TLS_METHOD DOWNLOADER_CLIENT_TLS_METHOD ---------------------------- Default: ``'TLS'`` Use this setting to customize the TLS/SSL method used by the default HTTP/1.1 downloader. This setting must be one of these string values: - ``'TLS'``: maps to OpenSSL's ``TLS_method()`` (a.k.a ``SSLv23_method()``), which allows protocol negotiation, starting from the highest supported by the platform; **default, recommended** - ``'TLSv1.0'``: this value forces HTTPS connections to use TLS version 1.0 ; set this if you want the behavior of Scrapy<1.1 - ``'TLSv1.1'``: forces TLS version 1.1 - ``'TLSv1.2'``: forces TLS version 1.2 - ``'SSLv3'``: forces SSL version 3 (**not recommended**) .. note:: We recommend that you use PyOpenSSL>=0.13 and Twisted>=0.13 or above (Twisted>=14.0 if you can). .. setting:: DOWNLOADER_MIDDLEWARES DOWNLOADER_MIDDLEWARES ---------------------- Default:: ``{}`` A dict containing the downloader middlewares enabled in your project, and their orders. For more info see :ref:`topics-downloader-middleware-setting`. .. setting:: DOWNLOADER_MIDDLEWARES_BASE DOWNLOADER_MIDDLEWARES_BASE --------------------------- Default:: { 'scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware': 100, 'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware': 300, 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware': 350, 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware': 400, 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware': 500, 'scrapy.downloadermiddlewares.retry.RetryMiddleware': 550, 'scrapy.downloadermiddlewares.ajaxcrawl.AjaxCrawlMiddleware': 560, 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware': 580, 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware': 590, 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware': 600, 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware': 700, 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware': 750, 'scrapy.downloadermiddlewares.stats.DownloaderStats': 850, 'scrapy.downloadermiddlewares.httpcache.HttpCacheMiddleware': 900, } A dict containing the downloader middlewares enabled by default in Scrapy. Low orders are closer to the engine, high orders are closer to the downloader. You should never modify this setting in your project, modify :setting:`DOWNLOADER_MIDDLEWARES` instead. For more info see :ref:`topics-downloader-middleware-setting`. .. setting:: DOWNLOADER_STATS DOWNLOADER_STATS ---------------- Default: ``True`` Whether to enable downloader stats collection. .. setting:: DOWNLOAD_DELAY DOWNLOAD_DELAY -------------- Default: ``0`` The amount of time (in secs) that the downloader should wait before downloading consecutive pages from the same website. This can be used to throttle the crawling speed to avoid hitting servers too hard. Decimal numbers are supported. Example:: DOWNLOAD_DELAY = 0.25 # 250 ms of delay This setting is also affected by the :setting:`RANDOMIZE_DOWNLOAD_DELAY` setting (which is enabled by default). By default, Scrapy doesn't wait a fixed amount of time between requests, but uses a random interval between 0.5 * :setting:`DOWNLOAD_DELAY` and 1.5 * :setting:`DOWNLOAD_DELAY`. When :setting:`CONCURRENT_REQUESTS_PER_IP` is non-zero, delays are enforced per ip address instead of per domain. You can also change this setting per spider by setting ``download_delay`` spider attribute. .. setting:: DOWNLOAD_HANDLERS DOWNLOAD_HANDLERS ----------------- Default: ``{}`` A dict containing the request downloader handlers enabled in your project. See :setting:`DOWNLOAD_HANDLERS_BASE` for example format. .. setting:: DOWNLOAD_HANDLERS_BASE DOWNLOAD_HANDLERS_BASE ---------------------- Default:: { 'file': 'scrapy.core.downloader.handlers.file.FileDownloadHandler', 'http': 'scrapy.core.downloader.handlers.http.HTTPDownloadHandler', 'https': 'scrapy.core.downloader.handlers.http.HTTPDownloadHandler', 's3': 'scrapy.core.downloader.handlers.s3.S3DownloadHandler', 'ftp': 'scrapy.core.downloader.handlers.ftp.FTPDownloadHandler', } A dict containing the request download handlers enabled by default in Scrapy. You should never modify this setting in your project, modify :setting:`DOWNLOAD_HANDLERS` instead. You can disable any of these download handlers by assigning ``None`` to their URI scheme in :setting:`DOWNLOAD_HANDLERS`. E.g., to disable the built-in FTP handler (without replacement), place this in your ``settings.py``:: DOWNLOAD_HANDLERS = { 'ftp': None, } .. setting:: DOWNLOAD_TIMEOUT DOWNLOAD_TIMEOUT ---------------- Default: ``180`` The amount of time (in secs) that the downloader will wait before timing out. .. note:: This timeout can be set per spider using :attr:`download_timeout` spider attribute and per-request using :reqmeta:`download_timeout` Request.meta key. .. setting:: DOWNLOAD_MAXSIZE DOWNLOAD_MAXSIZE ---------------- Default: `1073741824` (1024MB) The maximum response size (in bytes) that downloader will download. If you want to disable it set to 0. .. reqmeta:: download_maxsize .. note:: This size can be set per spider using :attr:`download_maxsize` spider attribute and per-request using :reqmeta:`download_maxsize` Request.meta key. This feature needs Twisted >= 11.1. .. setting:: DOWNLOAD_WARNSIZE DOWNLOAD_WARNSIZE ----------------- Default: `33554432` (32MB) The response size (in bytes) that downloader will start to warn. If you want to disable it set to 0. .. note:: This size can be set per spider using :attr:`download_warnsize` spider attribute and per-request using :reqmeta:`download_warnsize` Request.meta key. This feature needs Twisted >= 11.1. .. setting:: DOWNLOAD_FAIL_ON_DATALOSS DOWNLOAD_FAIL_ON_DATALOSS ------------------------- Default: ``True`` Whether or not to fail on broken responses, that is, declared ``Content-Length`` does not match content sent by the server or chunked response was not properly finish. If ``True``, these responses raise a ``ResponseFailed([_DataLoss])`` error. If ``False``, these responses are passed through and the flag ``dataloss`` is added to the response, i.e.: ``'dataloss' in response.flags`` is ``True``. Optionally, this can be set per-request basis by using the :reqmeta:`download_fail_on_dataloss` Request.meta key to ``False``. .. note:: A broken response, or data loss error, may happen under several circumstances, from server misconfiguration to network errors to data corruption. It is up to the user to decide if it makes sense to process broken responses considering they may contain partial or incomplete content. If :setting:`RETRY_ENABLED` is ``True`` and this setting is set to ``True``, the ``ResponseFailed([_DataLoss])`` failure will be retried as usual. .. setting:: DUPEFILTER_CLASS DUPEFILTER_CLASS ---------------- Default: ``'scrapy.dupefilters.RFPDupeFilter'`` The class used to detect and filter duplicate requests. The default (``RFPDupeFilter``) filters based on request fingerprint using the ``scrapy.utils.request.request_fingerprint`` function. In order to change the way duplicates are checked you could subclass ``RFPDupeFilter`` and override its ``request_fingerprint`` method. This method should accept scrapy :class:`~scrapy.http.Request` object and return its fingerprint (a string). You can disable filtering of duplicate requests by setting :setting:`DUPEFILTER_CLASS` to ``'scrapy.dupefilters.BaseDupeFilter'``. Be very careful about this however, because you can get into crawling loops. It's usually a better idea to set the ``dont_filter`` parameter to ``True`` on the specific :class:`~scrapy.http.Request` that should not be filtered. .. setting:: DUPEFILTER_DEBUG DUPEFILTER_DEBUG ---------------- Default: ``False`` By default, ``RFPDupeFilter`` only logs the first duplicate request. Setting :setting:`DUPEFILTER_DEBUG` to ``True`` will make it log all duplicate requests. .. setting:: EDITOR EDITOR ------ Default: ``vi`` (on Unix systems) or the IDLE editor (on Windows) The editor to use for editing spiders with the :command:`edit` command. Additionally, if the ``EDITOR`` environment variable is set, the :command:`edit` command will prefer it over the default setting. .. setting:: EXTENSIONS EXTENSIONS ---------- Default:: ``{}`` A dict containing the extensions enabled in your project, and their orders. .. setting:: EXTENSIONS_BASE EXTENSIONS_BASE --------------- Default:: { 'scrapy.extensions.corestats.CoreStats': 0, 'scrapy.extensions.telnet.TelnetConsole': 0, 'scrapy.extensions.memusage.MemoryUsage': 0, 'scrapy.extensions.memdebug.MemoryDebugger': 0, 'scrapy.extensions.closespider.CloseSpider': 0, 'scrapy.extensions.feedexport.FeedExporter': 0, 'scrapy.extensions.logstats.LogStats': 0, 'scrapy.extensions.spiderstate.SpiderState': 0, 'scrapy.extensions.throttle.AutoThrottle': 0, } A dict containing the extensions available by default in Scrapy, and their orders. This setting contains all stable built-in extensions. Keep in mind that some of them need to be enabled through a setting. For more information See the :ref:`extensions user guide ` and the :ref:`list of available extensions `. .. setting:: FEED_TEMPDIR FEED_TEMPDIR ------------ The Feed Temp dir allows you to set a custom folder to save crawler temporary files before uploading with :ref:`FTP feed storage ` and :ref:`Amazon S3 `. .. setting:: FTP_PASSIVE_MODE FTP_PASSIVE_MODE ---------------- Default: ``True`` Whether or not to use passive mode when initiating FTP transfers. .. setting:: FTP_PASSWORD FTP_PASSWORD ------------ Default: ``"guest"`` The password to use for FTP connections when there is no ``"ftp_password"`` in ``Request`` meta. .. note:: Paraphrasing `RFC 1635`_, although it is common to use either the password "guest" or one's e-mail address for anonymous FTP, some FTP servers explicitly ask for the user's e-mail address and will not allow login with the "guest" password. .. _RFC 1635: https://tools.ietf.org/html/rfc1635 .. setting:: FTP_USER FTP_USER -------- Default: ``"anonymous"`` The username to use for FTP connections when there is no ``"ftp_user"`` in ``Request`` meta. .. setting:: ITEM_PIPELINES ITEM_PIPELINES -------------- Default: ``{}`` A dict containing the item pipelines to use, and their orders. Order values are arbitrary, but it is customary to define them in the 0-1000 range. Lower orders process before higher orders. Example:: ITEM_PIPELINES = { 'mybot.pipelines.validate.ValidateMyItem': 300, 'mybot.pipelines.validate.StoreMyItem': 800, } .. setting:: ITEM_PIPELINES_BASE ITEM_PIPELINES_BASE ------------------- Default: ``{}`` A dict containing the pipelines enabled by default in Scrapy. You should never modify this setting in your project, modify :setting:`ITEM_PIPELINES` instead. .. setting:: LOG_ENABLED LOG_ENABLED ----------- Default: ``True`` Whether to enable logging. .. setting:: LOG_ENCODING LOG_ENCODING ------------ Default: ``'utf-8'`` The encoding to use for logging. .. setting:: LOG_FILE LOG_FILE -------- Default: ``None`` File name to use for logging output. If ``None``, standard error will be used. .. setting:: LOG_FORMAT LOG_FORMAT ---------- Default: ``'%(asctime)s [%(name)s] %(levelname)s: %(message)s'`` String for formatting log messsages. Refer to the `Python logging documentation`_ for the whole list of available placeholders. .. _Python logging documentation: https://docs.python.org/2/library/logging.html#logrecord-attributes .. setting:: LOG_DATEFORMAT LOG_DATEFORMAT -------------- Default: ``'%Y-%m-%d %H:%M:%S'`` String for formatting date/time, expansion of the ``%(asctime)s`` placeholder in :setting:`LOG_FORMAT`. Refer to the `Python datetime documentation`_ for the whole list of available directives. .. _Python datetime documentation: https://docs.python.org/2/library/datetime.html#strftime-and-strptime-behavior .. setting:: LOG_LEVEL LOG_LEVEL --------- Default: ``'DEBUG'`` Minimum level to log. Available levels are: CRITICAL, ERROR, WARNING, INFO, DEBUG. For more info see :ref:`topics-logging`. .. setting:: LOG_STDOUT LOG_STDOUT ---------- Default: ``False`` If ``True``, all standard output (and error) of your process will be redirected to the log. For example if you ``print 'hello'`` it will appear in the Scrapy log. .. setting:: LOG_SHORT_NAMES LOG_SHORT_NAMES --------------- Default: ``False`` If ``True``, the logs will just contain the root path. If it is set to ``False`` then it displays the component responsible for the log output .. setting:: MEMDEBUG_ENABLED MEMDEBUG_ENABLED ---------------- Default: ``False`` Whether to enable memory debugging. .. setting:: MEMDEBUG_NOTIFY MEMDEBUG_NOTIFY --------------- Default: ``[]`` When memory debugging is enabled a memory report will be sent to the specified addresses if this setting is not empty, otherwise the report will be written to the log. Example:: MEMDEBUG_NOTIFY = ['user@example.com'] .. setting:: MEMUSAGE_ENABLED MEMUSAGE_ENABLED ---------------- Default: ``True`` Scope: ``scrapy.extensions.memusage`` Whether to enable the memory usage extension. This extension keeps track of a peak memory used by the process (it writes it to stats). It can also optionally shutdown the Scrapy process when it exceeds a memory limit (see :setting:`MEMUSAGE_LIMIT_MB`), and notify by email when that happened (see :setting:`MEMUSAGE_NOTIFY_MAIL`). See :ref:`topics-extensions-ref-memusage`. .. setting:: MEMUSAGE_LIMIT_MB MEMUSAGE_LIMIT_MB ----------------- Default: ``0`` Scope: ``scrapy.extensions.memusage`` The maximum amount of memory to allow (in megabytes) before shutting down Scrapy (if MEMUSAGE_ENABLED is True). If zero, no check will be performed. See :ref:`topics-extensions-ref-memusage`. .. setting:: MEMUSAGE_CHECK_INTERVAL_SECONDS MEMUSAGE_CHECK_INTERVAL_SECONDS ------------------------------- .. versionadded:: 1.1 Default: ``60.0`` Scope: ``scrapy.extensions.memusage`` The :ref:`Memory usage extension ` checks the current memory usage, versus the limits set by :setting:`MEMUSAGE_LIMIT_MB` and :setting:`MEMUSAGE_WARNING_MB`, at fixed time intervals. This sets the length of these intervals, in seconds. See :ref:`topics-extensions-ref-memusage`. .. setting:: MEMUSAGE_NOTIFY_MAIL MEMUSAGE_NOTIFY_MAIL -------------------- Default: ``False`` Scope: ``scrapy.extensions.memusage`` A list of emails to notify if the memory limit has been reached. Example:: MEMUSAGE_NOTIFY_MAIL = ['user@example.com'] See :ref:`topics-extensions-ref-memusage`. .. setting:: MEMUSAGE_WARNING_MB MEMUSAGE_WARNING_MB ------------------- Default: ``0`` Scope: ``scrapy.extensions.memusage`` The maximum amount of memory to allow (in megabytes) before sending a warning email notifying about it. If zero, no warning will be produced. .. setting:: NEWSPIDER_MODULE NEWSPIDER_MODULE ---------------- Default: ``''`` Module where to create new spiders using the :command:`genspider` command. Example:: NEWSPIDER_MODULE = 'mybot.spiders_dev' .. setting:: RANDOMIZE_DOWNLOAD_DELAY RANDOMIZE_DOWNLOAD_DELAY ------------------------ Default: ``True`` If enabled, Scrapy will wait a random amount of time (between 0.5 * :setting:`DOWNLOAD_DELAY` and 1.5 * :setting:`DOWNLOAD_DELAY`) while fetching requests from the same website. This randomization decreases the chance of the crawler being detected (and subsequently blocked) by sites which analyze requests looking for statistically significant similarities in the time between their requests. The randomization policy is the same used by `wget`_ ``--random-wait`` option. If :setting:`DOWNLOAD_DELAY` is zero (default) this option has no effect. .. _wget: http://www.gnu.org/software/wget/manual/wget.html .. setting:: REACTOR_THREADPOOL_MAXSIZE REACTOR_THREADPOOL_MAXSIZE -------------------------- Default: ``10`` The maximum limit for Twisted Reactor thread pool size. This is common multi-purpose thread pool used by various Scrapy components. Threaded DNS Resolver, BlockingFeedStorage, S3FilesStore just to name a few. Increase this value if you're experiencing problems with insufficient blocking IO. .. setting:: REDIRECT_MAX_TIMES REDIRECT_MAX_TIMES ------------------ Default: ``20`` Defines the maximum times a request can be redirected. After this maximum the request's response is returned as is. We used Firefox default value for the same task. .. setting:: REDIRECT_PRIORITY_ADJUST REDIRECT_PRIORITY_ADJUST ------------------------ Default: ``+2`` Scope: ``scrapy.downloadermiddlewares.redirect.RedirectMiddleware`` Adjust redirect request priority relative to original request: - **a positive priority adjust (default) means higher priority.** - a negative priority adjust means lower priority. .. setting:: RETRY_PRIORITY_ADJUST RETRY_PRIORITY_ADJUST --------------------- Default: ``-1`` Scope: ``scrapy.downloadermiddlewares.retry.RetryMiddleware`` Adjust retry request priority relative to original request: - a positive priority adjust means higher priority. - **a negative priority adjust (default) means lower priority.** .. setting:: ROBOTSTXT_OBEY ROBOTSTXT_OBEY -------------- Default: ``False`` Scope: ``scrapy.downloadermiddlewares.robotstxt`` If enabled, Scrapy will respect robots.txt policies. For more information see :ref:`topics-dlmw-robots`. .. note:: While the default value is ``False`` for historical reasons, this option is enabled by default in settings.py file generated by ``scrapy startproject`` command. .. setting:: SCHEDULER SCHEDULER --------- Default: ``'scrapy.core.scheduler.Scheduler'`` The scheduler to use for crawling. .. setting:: SCHEDULER_DEBUG SCHEDULER_DEBUG --------------- Default: ``False`` Setting to ``True`` will log debug information about the requests scheduler. This currently logs (only once) if the requests cannot be serialized to disk. Stats counter (``scheduler/unserializable``) tracks the number of times this happens. Example entry in logs:: 1956-01-31 00:00:00+0800 [scrapy.core.scheduler] ERROR: Unable to serialize request: - reason: cannot serialize (type Request)> - no more unserializable requests will be logged (see 'scheduler/unserializable' stats counter) .. setting:: SCHEDULER_DISK_QUEUE SCHEDULER_DISK_QUEUE -------------------- Default: ``'scrapy.squeues.PickleLifoDiskQueue'`` Type of disk queue that will be used by scheduler. Other available types are ``scrapy.squeues.PickleFifoDiskQueue``, ``scrapy.squeues.MarshalFifoDiskQueue``, ``scrapy.squeues.MarshalLifoDiskQueue``. .. setting:: SCHEDULER_MEMORY_QUEUE SCHEDULER_MEMORY_QUEUE ---------------------- Default: ``'scrapy.squeues.LifoMemoryQueue'`` Type of in-memory queue used by scheduler. Other available type is: ``scrapy.squeues.FifoMemoryQueue``. .. setting:: SCHEDULER_PRIORITY_QUEUE SCHEDULER_PRIORITY_QUEUE ------------------------ Default: ``'queuelib.PriorityQueue'`` Type of priority queue used by scheduler. .. setting:: SPIDER_CONTRACTS SPIDER_CONTRACTS ---------------- Default:: ``{}`` A dict containing the spider contracts enabled in your project, used for testing spiders. For more info see :ref:`topics-contracts`. .. setting:: SPIDER_CONTRACTS_BASE SPIDER_CONTRACTS_BASE --------------------- Default:: { 'scrapy.contracts.default.UrlContract' : 1, 'scrapy.contracts.default.ReturnsContract': 2, 'scrapy.contracts.default.ScrapesContract': 3, } A dict containing the scrapy contracts enabled by default in Scrapy. You should never modify this setting in your project, modify :setting:`SPIDER_CONTRACTS` instead. For more info see :ref:`topics-contracts`. You can disable any of these contracts by assigning ``None`` to their class path in :setting:`SPIDER_CONTRACTS`. E.g., to disable the built-in ``ScrapesContract``, place this in your ``settings.py``:: SPIDER_CONTRACTS = { 'scrapy.contracts.default.ScrapesContract': None, } .. setting:: SPIDER_LOADER_CLASS SPIDER_LOADER_CLASS ------------------- Default: ``'scrapy.spiderloader.SpiderLoader'`` The class that will be used for loading spiders, which must implement the :ref:`topics-api-spiderloader`. .. setting:: SPIDER_LOADER_WARN_ONLY SPIDER_LOADER_WARN_ONLY ----------------------- .. versionadded:: 1.3.3 Default: ``False`` By default, when scrapy tries to import spider classes from :setting:`SPIDER_MODULES`, it will fail loudly if there is any ``ImportError`` exception. But you can choose to silence this exception and turn it into a simple warning by setting ``SPIDER_LOADER_WARN_ONLY = True``. .. note:: Some :ref:`scrapy commands ` run with this setting to ``True`` already (i.e. they will only issue a warning and will not fail) since they do not actually need to load spider classes to work: :command:`scrapy runspider `, :command:`scrapy settings `, :command:`scrapy startproject `, :command:`scrapy version `. .. setting:: SPIDER_MIDDLEWARES SPIDER_MIDDLEWARES ------------------ Default:: ``{}`` A dict containing the spider middlewares enabled in your project, and their orders. For more info see :ref:`topics-spider-middleware-setting`. .. setting:: SPIDER_MIDDLEWARES_BASE SPIDER_MIDDLEWARES_BASE ----------------------- Default:: { 'scrapy.spidermiddlewares.httperror.HttpErrorMiddleware': 50, 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware': 500, 'scrapy.spidermiddlewares.referer.RefererMiddleware': 700, 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware': 800, 'scrapy.spidermiddlewares.depth.DepthMiddleware': 900, } A dict containing the spider middlewares enabled by default in Scrapy, and their orders. Low orders are closer to the engine, high orders are closer to the spider. For more info see :ref:`topics-spider-middleware-setting`. .. setting:: SPIDER_MODULES SPIDER_MODULES -------------- Default: ``[]`` A list of modules where Scrapy will look for spiders. Example:: SPIDER_MODULES = ['mybot.spiders_prod', 'mybot.spiders_dev'] .. setting:: STATS_CLASS STATS_CLASS ----------- Default: ``'scrapy.statscollectors.MemoryStatsCollector'`` The class to use for collecting stats, who must implement the :ref:`topics-api-stats`. .. setting:: STATS_DUMP STATS_DUMP ---------- Default: ``True`` Dump the :ref:`Scrapy stats ` (to the Scrapy log) once the spider finishes. For more info see: :ref:`topics-stats`. .. setting:: STATSMAILER_RCPTS STATSMAILER_RCPTS ----------------- Default: ``[]`` (empty list) Send Scrapy stats after spiders finish scraping. See :class:`~scrapy.extensions.statsmailer.StatsMailer` for more info. .. setting:: TELNETCONSOLE_ENABLED TELNETCONSOLE_ENABLED --------------------- Default: ``True`` A boolean which specifies if the :ref:`telnet console ` will be enabled (provided its extension is also enabled). .. setting:: TELNETCONSOLE_PORT TELNETCONSOLE_PORT ------------------ Default: ``[6023, 6073]`` The port range to use for the telnet console. If set to ``None`` or ``0``, a dynamically assigned port is used. For more info see :ref:`topics-telnetconsole`. .. setting:: TEMPLATES_DIR TEMPLATES_DIR ------------- Default: ``templates`` dir inside scrapy module The directory where to look for templates when creating new projects with :command:`startproject` command and new spiders with :command:`genspider` command. The project name must not conflict with the name of custom files or directories in the ``project`` subdirectory. .. setting:: URLLENGTH_LIMIT URLLENGTH_LIMIT --------------- Default: ``2083`` Scope: ``spidermiddlewares.urllength`` The maximum URL length to allow for crawled URLs. For more information about the default value for this setting see: http://www.boutell.com/newfaq/misc/urllength.html .. setting:: USER_AGENT USER_AGENT ---------- Default: ``"Scrapy/VERSION (+http://scrapy.org)"`` The default User-Agent to use when crawling, unless overridden. Settings documented elsewhere: ------------------------------ The following settings are documented elsewhere, please check each specific case to see how to enable and use them. .. settingslist:: .. _Amazon web services: https://aws.amazon.com/ .. _breadth-first order: https://en.wikipedia.org/wiki/Breadth-first_search .. _depth-first order: https://en.wikipedia.org/wiki/Depth-first_search