settings.rst 24.7 KB
Newer Older
P
Pablo Hoffman 已提交
1 2
.. _topics-settings:

3 4 5
========
Settings
========
6 7 8 9

The Scrapy settings allows you to customize the behaviour of all Scrapy
components, including the core, extensions, pipelines and spiders themselves.

10
The infrastructure of the settings provides a global namespace of key-value mappings
11
that the code can use to pull configuration values from. The settings can be
12 13
populated through different mechanisms, which are described below.

14
The settings are also the mechanism for selecting the currently active Scrapy
15
project (in case you have many).
16

17 18
For a list of available built-in settings see: :ref:`topics-settings-ref`.

19 20
.. _topics-settings-module-envvar:

21
Designating the settings
22 23
========================

24
When you use Scrapy, you have to tell it which settings you're using. You can
P
Pablo Hoffman 已提交
25
do this by using an environment variable, ``SCRAPY_SETTINGS_MODULE``.
26 27 28 29 30

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`_.

31
.. _import search path: https://docs.python.org/2/tutorial/modules.html#the-module-search-path
32 33 34 35

Populating the settings
=======================

36 37 38 39
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:

J
Julia Medina 已提交
40
 1. Command line options (most precedence)
J
Julia Medina 已提交
41 42 43 44
 2. Settings per-spider
 3. Project settings module
 4. Default settings per-command
 5. Default global settings (less precedence)
45

J
Julia Medina 已提交
46 47 48
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.
49

J
Julia Medina 已提交
50
These mechanisms are described in more detail below.
51

J
Julia Medina 已提交
52 53
1. Command line options
-----------------------
54

J
Julia Medina 已提交
55 56 57
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.
58

P
Pablo Hoffman 已提交
59 60
.. highlight:: sh

61 62
Example::

63
    scrapy crawl myspider -s LOG_FILE=scrapy.log
64

J
Julia Medina 已提交
65 66 67 68 69 70 71 72
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.spider.Spider.custom_settings` attribute.

3. Project settings module
73
--------------------------
74

75 76 77
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
example:: ``myproject.settings``.
78

J
Julia Medina 已提交
79
4. Default settings per-command
P
Pablo Hoffman 已提交
80 81
-------------------------------

82 83 84 85
Each :doc:`Scrapy tool </topics/commands>` 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.
P
Pablo Hoffman 已提交
86

J
Julia Medina 已提交
87
5. Default global settings
P
Pablo Hoffman 已提交
88
--------------------------
89

90 91
The global defaults are located in the ``scrapy.settings.default_settings``
module and documented in the :ref:`topics-settings-ref` section.
92 93 94 95

How to access settings
======================

P
Pablo Hoffman 已提交
96 97
.. highlight:: python

98 99 100 101 102
Settings can be accessed through the :attr:`scrapy.crawler.Crawler.settings`
attribute of the Crawler that is passed to ``from_crawler`` method in
extensions and middlewares::

    class MyExtension(object):
103

104 105 106 107 108
        @classmethod
        def from_crawler(cls, crawler):
            settings = crawler.settings
            if settings['LOG_ENABLED']:
                print "log is enabled!"
109

110
In other words, settings can be accessed like a dict, but it's usually preferred
P
Pablo Hoffman 已提交
111
to extract the setting in the format you need it to avoid type errors. In order
112 113
to do that you'll have to use one of the methods provided the
:class:`~scrapy.settings.Settings` API.
P
Pablo Hoffman 已提交
114

115 116 117 118
Rationale for setting names
===========================

Setting names are usually prefixed with the component that they configure. For
P
Pablo Hoffman 已提交
119
example, proper setting names for a fictional robots.txt extension would be
120
``ROBOTSTXT_ENABLED``, ``ROBOTSTXT_OBEY``, ``ROBOTSTXT_CACHEDIR``, etc.
121 122 123 124 125 126 127 128


.. _topics-settings-ref:

Built-in settings reference
===========================

Here's a list of all available Scrapy settings, in alphabetical order, along
129
with their default values and the scope where they apply.
130 131 132 133 134 135

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.

136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155
.. 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 <topics-feed-storage-s3>`.

.. 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 <topics-feed-storage-s3>`.

156 157 158 159 160
.. setting:: BOT_NAME

BOT_NAME
--------

161
Default: ``'scrapybot'``
162

163 164 165 166 167
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
168
project with the :command:`startproject` command.
169 170 171 172 173 174 175 176 177

.. setting:: CONCURRENT_ITEMS

CONCURRENT_ITEMS
----------------

Default: ``100``

Maximum number of concurrent items (per response) to process in parallel in the
178 179
Item Processor (also known as the :ref:`Item Pipeline <topics-item-pipeline>`).

180
.. setting:: CONCURRENT_REQUESTS
181

182 183 184 185 186 187 188 189 190 191 192 193
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
194 195 196 197
------------------------------

Default: ``8``

198 199 200 201 202 203 204 205 206 207 208 209 210 211 212
The maximum number of concurrent (ie. simultaneous) requests that will be
performed to any single domain.

.. 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.
213

214 215 216 217 218
This setting also affects :setting:`DOWNLOAD_DELAY`:
if :setting:`CONCURRENT_REQUESTS_PER_IP` is non-zero, download delay is
enforced per IP, not per domain.


219 220 221 222 223
.. setting:: DEFAULT_ITEM_CLASS

DEFAULT_ITEM_CLASS
------------------

224
Default: ``'scrapy.item.Item'``
225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253

The default class that will be used for instantiating items in the :ref:`the
Scrapy shell <topics-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.contrib.downloadermiddleware.defaultheaders.DefaultHeadersMiddleware`.

.. setting:: DEPTH_LIMIT

DEPTH_LIMIT
-----------

Default: ``0``

The maximum depth that will be allowed to crawl for any site. If zero, no limit
will be imposed.

254 255 256 257 258
.. setting:: DEPTH_PRIORITY

DEPTH_PRIORITY
--------------

259
Default: ``0``
260

261
An integer that is used to adjust the request priority based on its depth.
262

263
If zero, no priority adjustment is made from depth.
264

265 266 267 268 269 270 271
.. setting:: DEPTH_STATS

DEPTH_STATS
-----------

Default: ``True``

272 273 274 275 276 277 278 279 280 281 282
Whether to collect maximum depth stats.

.. setting:: DEPTH_STATS_VERBOSE

DEPTH_STATS_VERBOSE
-------------------

Default: ``False``

Whether to collect verbose depth stats. If this is enabled, the number of
requests for each depth is collected in the stats.
283

284 285 286 287 288 289 290 291 292
.. setting:: DNSCACHE_ENABLED

DNSCACHE_ENABLED
----------------

Default: ``True``

Whether to enable DNS in-memory cache.

A
Alexander Chekunkov 已提交
293 294 295
.. setting:: DOWNLOADER

DOWNLOADER
A
Alexander Chekunkov 已提交
296
----------
A
Alexander Chekunkov 已提交
297 298 299 300 301

Default: ``'scrapy.core.downloader.Downloader'``

The downloader to use for crawling.

302 303 304 305 306 307 308 309 310 311 312 313 314 315 316
.. 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
---------------------------

317
Default::
318 319 320 321

    {
        'scrapy.contrib.downloadermiddleware.robotstxt.RobotsTxtMiddleware': 100,
        'scrapy.contrib.downloadermiddleware.httpauth.HttpAuthMiddleware': 300,
P
Pablo Hoffman 已提交
322
        'scrapy.contrib.downloadermiddleware.downloadtimeout.DownloadTimeoutMiddleware': 350,
323 324 325
        'scrapy.contrib.downloadermiddleware.useragent.UserAgentMiddleware': 400,
        'scrapy.contrib.downloadermiddleware.retry.RetryMiddleware': 500,
        'scrapy.contrib.downloadermiddleware.defaultheaders.DefaultHeadersMiddleware': 550,
326 327
        'scrapy.contrib.downloadermiddleware.redirect.MetaRefreshMiddleware': 580,
        'scrapy.contrib.downloadermiddleware.httpcompression.HttpCompressionMiddleware': 590,
328 329
        'scrapy.contrib.downloadermiddleware.redirect.RedirectMiddleware': 600,
        'scrapy.contrib.downloadermiddleware.cookies.CookiesMiddleware': 700,
330
        'scrapy.contrib.downloadermiddleware.httpproxy.HttpProxyMiddleware': 750,
331
        'scrapy.contrib.downloadermiddleware.chunked.ChunkedTransferMiddleware': 830,
332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357
        'scrapy.contrib.downloadermiddleware.stats.DownloaderStats': 850,
        'scrapy.contrib.downloadermiddleware.httpcache.HttpCacheMiddleware': 900,
    }

A dict containing the downloader middlewares enabled by default in Scrapy. 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
358
consecutive pages from the same website. This can be used to throttle the
359 360 361
crawling speed to avoid hitting servers too hard. Decimal numbers are
supported.  Example::

362
    DOWNLOAD_DELAY = 0.25    # 250 ms of delay
363

364 365 366 367 368
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 and 1.5
* :setting:`DOWNLOAD_DELAY`.

369 370 371 372 373
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.
374

375 376 377 378 379 380 381 382 383 384 385 386 387 388 389
.. setting:: DOWNLOAD_HANDLERS

DOWNLOAD_HANDLERS
-----------------

Default: ``{}``

A dict containing the request downloader handlers enabled in your project.
See `DOWNLOAD_HANDLERS_BASE` for example format.

.. setting:: DOWNLOAD_HANDLERS_BASE

DOWNLOAD_HANDLERS_BASE
----------------------

390
Default::
391 392 393 394 395 396 397 398 399 400

    {
        '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',
    }

A dict containing the request download handlers enabled by default in Scrapy.
You should never modify this setting in your project, modify
401
:setting:`DOWNLOAD_HANDLERS` instead.
402

403 404 405 406 407 408 409 410 411
If you want to disable any of the above download handlers you must define them
in your project's :setting:`DOWNLOAD_HANDLERS` setting and assign `None`
as their value.  For example, if you want to disable the file download
handler::

    DOWNLOAD_HANDLERS = {
        'file': None,
    }

412 413 414 415 416 417 418 419 420
.. setting:: DOWNLOAD_TIMEOUT

DOWNLOAD_TIMEOUT
----------------

Default: ``180``

The amount of time (in secs) that the downloader will wait before timing out.

421 422 423 424 425 426
.. note::

    This timeout can be set per spider using :attr:`download_timeout`
    spider attribute and per-request using :reqmeta:`download_timeout`
    Request.meta key.

T
tpeng 已提交
427 428 429 430 431
.. setting:: DOWNLOAD_MAXSIZE

DOWNLOAD_MAXSIZE
----------------

T
tpeng 已提交
432
Default: `1073741824` (1024MB)
T
tpeng 已提交
433 434 435 436 437

The maximum response size (in bytes) that downloader will download.

If you want to disable it set to 0.

438 439
.. reqmeta:: download_maxsize

T
tpeng 已提交
440 441 442 443 444 445
.. note::

    This size can be set per spider using :attr:`download_maxsize`
    spider attribute and per-request using :reqmeta:`download_maxsize`
    Request.meta key.

T
tpeng 已提交
446 447
    This feature needs Twisted >= 11.1.

T
tpeng 已提交
448 449 450
.. setting:: DOWNLOAD_WARNSIZE

DOWNLOAD_WARNSIZE
T
tpeng 已提交
451
-----------------
T
tpeng 已提交
452

T
tpeng 已提交
453
Default: `33554432` (32MB)
T
tpeng 已提交
454 455 456 457 458 459 460 461 462 463 464

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.

T
tpeng 已提交
465 466
    This feature needs Twisted >= 11.1.

467 468 469 470 471
.. setting:: DUPEFILTER_CLASS

DUPEFILTER_CLASS
----------------

472
Default: ``'scrapy.dupefilter.RFPDupeFilter'``
473 474 475

The class used to detect and filter duplicate requests.

476
The default (``RFPDupeFilter``) filters based on request fingerprint using
477 478
the ``scrapy.utils.request.request_fingerprint`` function. In order to change
the way duplicates are checked you could subclass ``RFPDupeFilter`` and
479 480 481
override its ``request_fingerprint`` method. This method should accept
scrapy :class:`~scrapy.http.Request` object and return its fingerprint
(a string).
482

483 484 485 486 487 488 489 490 491 492 493
.. 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
P
Pablo Hoffman 已提交
494 495 496 497

EDITOR
------

498 499
Default: `depends on the environment`

P
Pablo Hoffman 已提交
500 501 502 503
The editor to use for editing spiders with the :command:`edit` command. It
defaults to the ``EDITOR`` environment variable, if set. Otherwise, it defaults
to ``vi`` (on Unix systems) or the IDLE editor (on Windows).

504 505 506 507 508 509 510
.. setting:: EXTENSIONS

EXTENSIONS
----------

Default:: ``{}``

511
A dict containing the extensions enabled in your project, and their orders.
512 513 514 515 516 517

.. setting:: EXTENSIONS_BASE

EXTENSIONS_BASE
---------------

P
Pablo Hoffman 已提交
518
Default::
519 520

    {
521
        'scrapy.contrib.corestats.CoreStats': 0,
522
        'scrapy.telnet.TelnetConsole': 0,
523 524
        'scrapy.contrib.memusage.MemoryUsage': 0,
        'scrapy.contrib.memdebug.MemoryDebugger': 0,
P
Pablo Hoffman 已提交
525 526
        'scrapy.contrib.closespider.CloseSpider': 0,
        'scrapy.contrib.feedexport.FeedExporter': 0,
527
        'scrapy.contrib.logstats.LogStats': 0,
P
Pablo Hoffman 已提交
528
        'scrapy.contrib.spiderstate.SpiderState': 0,
529
        'scrapy.contrib.throttle.AutoThrottle': 0,
530 531
    }

532
The list of available extensions. Keep in mind that some of them need to
533
be enabled through a setting. By default, this setting contains all stable
534
built-in extensions.
535 536 537 538 539 540 541 542 543

For more information See the :ref:`extensions user guide  <topics-extensions>`
and the :ref:`list of available extensions <topics-extensions-ref>`.

.. setting:: ITEM_PIPELINES

ITEM_PIPELINES
--------------

544 545 546 547 548
Default: ``{}``

A dict containing the item pipelines to use, and their orders. The dict is
empty by default order values are arbitrary but it's customary to define them
in the 0-1000 range.
549

550 551
Lists are supported in :setting:`ITEM_PIPELINES` for backwards compatibility,
but they are deprecated.
552 553 554

Example::

555
   ITEM_PIPELINES = {
556 557
       'mybot.pipelines.validate.ValidateMyItem': 300,
       'mybot.pipelines.validate.StoreMyItem': 800,
558 559 560 561 562 563 564 565 566 567 568
   }

.. 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.
569 570 571 572 573 574 575 576

.. setting:: LOG_ENABLED

LOG_ENABLED
-----------

Default: ``True``

P
Pablo Hoffman 已提交
577 578 579 580 581 582 583 584 585 586
Whether to enable logging.

.. setting:: LOG_ENCODING

LOG_ENCODING
------------

Default: ``'utf-8'``

The encoding to use for logging.
587

588
.. setting:: LOG_FILE
589

590 591
LOG_FILE
--------
592 593 594

Default: ``None``

595
File name to use for logging output. If None, standard error will be used.
596

597
.. setting:: LOG_LEVEL
598

599 600
LOG_LEVEL
---------
601 602 603

Default: ``'DEBUG'``

604 605
Minimum level to log. Available levels are: CRITICAL, ERROR, WARNING,
INFO, DEBUG. For more info see :ref:`topics-logging`.
606

607 608 609 610 611 612 613
.. setting:: LOG_STDOUT

LOG_STDOUT
----------

Default: ``False``

614 615 616
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.
617

618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696
.. 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: ``False``

Scope: ``scrapy.contrib.memusage``

Whether to enable the memory usage extension that will shutdown the Scrapy
process when it exceeds a memory limit, and also notify by email when that
happened.

See :ref:`topics-extensions-ref-memusage`.

.. setting:: MEMUSAGE_LIMIT_MB

MEMUSAGE_LIMIT_MB
-----------------

Default: ``0``

Scope: ``scrapy.contrib.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_NOTIFY_MAIL

MEMUSAGE_NOTIFY_MAIL
--------------------

Default: ``False``

Scope: ``scrapy.contrib.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_REPORT

MEMUSAGE_REPORT
---------------

Default: ``False``

Scope: ``scrapy.contrib.memusage``

P
Pablo Hoffman 已提交
697
Whether to send a memory usage report after each spider has been closed.
698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719

See :ref:`topics-extensions-ref-memusage`.

.. setting:: MEMUSAGE_WARNING_MB

MEMUSAGE_WARNING_MB
-------------------

Default: ``0``

Scope: ``scrapy.contrib.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: ``''``

720
Module where to create new spiders using the :command:`genspider` command.
721 722 723 724 725

Example::

    NEWSPIDER_MODULE = 'mybot.spiders_dev'

726 727 728 729 730 731 732 733 734
.. setting:: RANDOMIZE_DOWNLOAD_DELAY

RANDOMIZE_DOWNLOAD_DELAY
------------------------

Default: ``True``

If enabled, Scrapy will wait a random amount of time (between 0.5 and 1.5
* :setting:`DOWNLOAD_DELAY`) while fetching requests from the same
735
website.
736 737 738

This randomization decreases the chance of the crawler being detected (and
subsequently blocked) by sites which analyze requests looking for statistically
739
significant similarities in the time between their requests.
740 741 742 743 744 745 746

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

A
Alexander Sibiryakov 已提交
747 748 749
.. setting:: REACTOR_THREADPOOL_MAXSIZE

REACTOR_THREADPOOL_MAXSIZE
A
Alexander Sibiryakov 已提交
750
--------------------------
A
Alexander Sibiryakov 已提交
751 752 753

Default: ``10``

754 755 756 757
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.
A
Alexander Sibiryakov 已提交
758

759 760 761 762 763 764 765
.. setting:: REDIRECT_MAX_TIMES

REDIRECT_MAX_TIMES
------------------

Default: ``20``

766
Defines the maximum times a request can be redirected. After this maximum the
767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782
request's response is returned as is. We used Firefox default value for the
same task.

.. setting:: REDIRECT_MAX_METAREFRESH_DELAY

REDIRECT_MAX_METAREFRESH_DELAY
------------------------------

Default: ``100``

Some sites use meta-refresh for redirecting to a session expired page, so we
restrict automatic redirection to a maximum delay (in seconds)

.. setting:: REDIRECT_PRIORITY_ADJUST

REDIRECT_PRIORITY_ADJUST
P
Pablo Hoffman 已提交
783
------------------------
784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799

Default: ``+2``

Adjust redirect request priority relative to original request.
A negative priority adjust means more priority.

.. setting:: ROBOTSTXT_OBEY

ROBOTSTXT_OBEY
--------------

Default: ``False``

Scope: ``scrapy.contrib.downloadermiddleware.robotstxt``

If enabled, Scrapy will respect robots.txt policies. For more information see
800
:ref:`topics-dlmw-robots`
801 802 803 804 805 806 807 808 809 810

.. setting:: SCHEDULER

SCHEDULER
---------

Default: ``'scrapy.core.scheduler.Scheduler'``

The scheduler to use for crawling.

P
Pablo Hoffman 已提交
811
.. setting:: SPIDER_CONTRACTS
812 813 814 815 816 817 818

SPIDER_CONTRACTS
----------------

Default:: ``{}``

A dict containing the scrapy contracts enabled in your project, used for
819
testing spiders. For more info see :ref:`topics-contracts`.
820

P
Pablo Hoffman 已提交
821 822
.. setting:: SPIDER_CONTRACTS_BASE

823 824 825 826 827 828 829 830 831 832 833 834 835
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`
836
instead. For more info see :ref:`topics-contracts`.
837

J
Julia Medina 已提交
838 839 840 841 842 843 844 845 846 847
.. setting:: SPIDER_MANAGER_CLASS

SPIDER_MANAGER_CLASS
--------------------

Default: ``'scrapy.spidermanager.SpiderManager'``

The class that will be used for handling spiders, which must implement the
:ref:`topics-api-spidermanager`.

P
Pablo Hoffman 已提交
848 849
.. setting:: SPIDER_MIDDLEWARES

850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895
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.contrib.spidermiddleware.httperror.HttpErrorMiddleware': 50,
        'scrapy.contrib.spidermiddleware.offsite.OffsiteMiddleware': 500,
        'scrapy.contrib.spidermiddleware.referer.RefererMiddleware': 700,
        'scrapy.contrib.spidermiddleware.urllength.UrlLengthMiddleware': 800,
        'scrapy.contrib.spidermiddleware.depth.DepthMiddleware': 900,
    }

A dict containing the spider middlewares enabled by default in Scrapy. You
should never modify this setting in your project, modify
:setting:`SPIDER_MIDDLEWARES` instead. 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
-----------

896
Default: ``'scrapy.statscol.MemoryStatsCollector'``
897

898 899
The class to use for collecting stats, who must implement the
:ref:`topics-api-stats`.
900 901 902 903 904 905

.. setting:: STATS_DUMP

STATS_DUMP
----------

906 907
Default: ``True``

908 909
Dump the :ref:`Scrapy stats <topics-stats>` (to the Scrapy log) once the spider
finishes.
910

911
For more info see: :ref:`topics-stats`.
912 913 914 915 916 917 918 919

.. setting:: STATSMAILER_RCPTS

STATSMAILER_RCPTS
-----------------

Default: ``[]`` (empty list)

P
Pablo Hoffman 已提交
920
Send Scrapy stats after spiders finish scraping. See
921 922 923 924 925 926 927 928 929
:class:`~scrapy.contrib.statsmailer.StatsMailer` for more info.

.. setting:: TELNETCONSOLE_ENABLED

TELNETCONSOLE_ENABLED
---------------------

Default: ``True``

930 931
A boolean which specifies if the :ref:`telnet console <topics-telnetconsole>`
will be enabled (provided its extension is also enabled).
932 933 934 935 936 937

.. setting:: TELNETCONSOLE_PORT

TELNETCONSOLE_PORT
------------------

938
Default: ``[6023, 6073]``
939

940
The port range to use for the telnet console. If set to ``None`` or ``0``, a
941 942 943 944 945 946 947 948 949 950
dynamically assigned port is used. For more info see
:ref:`topics-telnetconsole`.

.. setting:: TEMPLATES_DIR

TEMPLATES_DIR
-------------

Default: ``templates`` dir inside scrapy module

951 952
The directory where to look for templates when creating new projects with
:command:`startproject` command.
953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970

.. setting:: URLLENGTH_LIMIT

URLLENGTH_LIMIT
---------------

Default: ``2083``

Scope: ``contrib.spidermiddleware.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
----------

971
Default: ``"Scrapy/VERSION (+http://scrapy.org)"``
972

973
The default User-Agent to use when crawling, unless overridden.
974

975
.. _Amazon web services: http://aws.amazon.com/
976 977
.. _breadth-first order: http://en.wikipedia.org/wiki/Breadth-first_search
.. _depth-first order: http://en.wikipedia.org/wiki/Depth-first_search