scrapy爬http返回503 Service Unavailablec错误
问题：scrapy shell 请求页面时返回503 Service Unavailablec错误
2018-07-08 15:30:23 [scrapy.downloadermiddlewares.retry] DEBUG: Gave up retrying
(failed 3 times): 503 Service Unavailable
2018-07-08 15:30:23 [scrapy.core.engine] DEBUG: Crawled (503) (referer: None)
2018-07-08 15:30:24 [traitlets] DEBUG: Using default logger
2018-07-08 15:30:24 [traitlets] DEBUG: Using default logger
[s] Available Scrapy objects:
[s] scrapy scrapy module (contains scrapy.Request, scrapy.Selector, etc)
[s] crawler
[s] item {}
[s] request
[s] response <503 http://www.xicidaili.com/nn/2>
[s] settings
[s] spider
补充：常见可能被网站识别返回错误
1、CAPTCHApages （captcha，验证码）
2、Unusualcontent delivery delay （响应时间、速度变慢了）
3、Frequentresponse with HTTP404,301 or 50x errors
（1）301 MovedTemporarily
（2）401unauthorized
（3）403forbidden （aAatch处理的）
（4）404 notfound
（5）408 requesttimeout
（6）429 too manyrequests
（7）503 serviceunavailable （ip层）
原因分析：
1、在settings中将rebots改为False，发现依旧返回503错误
# Obey robots.txt rules
ROBOTSTXT_OBEY = False2、再分析，浏览器中打开正常显示，scrapy跟浏览器请求是同一个ip，所以排除ip封锁问题。
网页不需要登录，排除cookie问题，剩下就是headers中user_agent的问题了。scrapy中添加user_agent之后，成功解决
结论：没有请求头，被网站识别为爬虫程序（所以要模拟浏览器访问）
解决（scrapy中设置随机user-agent）：
1、settings.py中添加
USER_AGENTS_LIST = [
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; AcooBrowser; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.0; Acoo Browser; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506)",
"Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.5; AOLBuild 4337.35; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)",
"Mozilla/5.0 (Windows; U; MSIE 9.0; Windows NT 9.0; en-US)",
"Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 2.0.50727; Media Center PC 6.0)",
"Mozilla/5.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET CLR 1.0.3705; .NET CLR 1.1.4322)",
"Mozilla/4.0 (compatible; MSIE 7.0b; Windows NT 5.2; .NET CLR 1.1.4322; .NET CLR 2.0.50727; InfoPath.2; .NET CLR 3.0.04506.30)",
"Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN) AppleWebKit/523.15 (KHTML, like Gecko, Safari/419.3) Arora/0.3 (Change: 287 c9dfb30)",
"Mozilla/5.0 (X11; U; Linux; en-US) AppleWebKit/527+ (KHTML, like Gecko, Safari/419.3) Arora/0.6",
"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.2pre) Gecko/20070215 K-Ninja/2.1.1",
"Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9) Gecko/20080705 Firefox/3.0 Kapiko/3.0",
"Mozilla/5.0 (X11; Linux i686; U;) Gecko/20070322 Kazehakase/0.4.5",
"Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.8) Gecko Fedora/1.9.0.8-1.fc10 Kazehakase/0.5.6",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.56 Safari/535.11",
"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/535.20 (KHTML, like Gecko) Chrome/19.0.1036.7 Safari/535.20",
"Opera/9.80 (Macintosh; Intel Mac OS X 10.6.8; U; fr) Presto/2.9.168 Version/11.52",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.11 TaoBrowser/2.0 Safari/536.11",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER",
"Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; LBBROWSER)",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E; LBBROWSER)",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 LBBROWSER",
"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E)",
"Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; QQBrowser/7.0.3698.400)",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E)",
"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SV1; QQDownload 732; .NET4.0C; .NET4.0E; 360SE)",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E)",
"Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E)",
"Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1",
"Mozilla/5.0 (iPad; U; CPU OS 4_2_1 like Mac OS X; zh-cn) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8C148 Safari/6533.18.5",
"Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b13pre) Gecko/20110307 Firefox/4.0b13pre",
"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:16.0) Gecko/20100101 Firefox/16.0",
"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11",
"Mozilla/5.0 (X11; U; Linux x86_64; zh-CN; rv:1.9.2.10) Gecko/20100922 Ubuntu/10.10 (maverick) Firefox/3.6.10"
]
2、新建randomAgentMiddleware.py
# -*- coding: utf-8 -*-
import scrapy
from scrapy import signals
from scrapy.downloadermiddlewares.useragent import UserAgentMiddleware
import random
class MyUserAgentMiddleware(UserAgentMiddleware):
'''
设置User-Agent
'''
def __init__(self, user_agent):
self.user_agent = user_agent
@classmethod
def from_crawler(cls, crawler):
return cls(
user_agent=crawler.settings.get('USER_AGENTS_LIST')
)
def process_request(self, request, spider):
agent = random.choice(self.user_agent)
request.headers['User-Agent'] = agent3、添加到DOWNLOADER_MIDDLEWARES
可以看到整个过程非常的简单，相关模块的导入就不说了，我们首先自定义了一个类，这个类继承自UserAgentMiddleware。之前已经说过，scrapy为我们提供了from_crawler()的方法，用于访问相关的设置信息，这里就是用到了这个方法，从settings里面取出我们的USER_AGENT列表，而后就是随机从列表中选择一个，添加到headers里面，最后默认返回了None。
最后一步，就是将我们自定义的这个MyUserAgentMiddleware类添加到DOWNLOADER_MIDDLEWARES，像下面这样。
DOWNLOADER_MIDDLEWARES = {
#'proxySpider.middlewares.MyCustomDownloaderMiddleware': 543,
'scrapy.downloadermiddleware.useragent.UserAgentMiddleware': None,
'proxySpider.randomAgentMiddleware.MyUserAgentMiddleware': 400,
}再次执行scrapy shell页面返回状态200如下，成功。
[s] Available Scrapy objects:
[s] scrapy scrapy module (contains scrapy.Request, scrapy.Selector, etc)
[s] crawler
[s] item {}
[s] request
[s] response <200 http://www.xicidaili.com/nn/2>
[s] settings
[s] spider
[s] Useful shortcuts:
[s] fetch(url[, redirect=True]) Fetch URL and update local objects (by default, redirects are followed)
[s] fetch(req) Fetch a scrapy.Request and update local objects
[s] shelp() Shell help (print this help)
[s] view(response) View response in a browser