[scrapy-redis] 将scrapy爬虫改造成分布式爬虫 (2)
1. 修改redis设置
redis默认处在protection mode, 修改/etc/redis.conf, protected-mode no, 或者给redis设置密码，
将bind 127.0.0.1这一行用#注释掉
2. 修改爬虫设置
向settings.py加入以下设置
REDIS_URL 为master的ip加上redis的端口号
# For scrapy_redis
# Enables scheduling storing requests queue in redis.
SCHEDULER = "scrapy_redis.scheduler.Scheduler"
# Ensure all spiders share same duplicates filter through redis.
DUPEFILTER_CLASS = "scrapy_redis.dupefilter.RFPDupeFilter"
# Don't cleanup redis queues, allows to pause/resume crawls.
SCHEDULER_PERSIST = True
# Schedule requests using a priority queue. (default)
SCHEDULER_QUEUE_CLASS = 'scrapy_redis.queue.PriorityQueue'
# Store scraped item in redis for post-processing.
ITEM_PIPELINES = {
'scrapy_redis.pipelines.RedisPipeline': 300
}
# Specify the host and port to use when connecting to Redis (optional).
#REDIS_HOST = 'localhost'
#REDIS_PORT = 6379
# Specify the full Redis URL for connecting (optional).
# If set, this takes precedence over the REDIS_HOST and REDIS_PORT settings.
#REDIS_URL = 'redis://user:pass@hostname:9001'
REDIS_URL = 'redis://192.168.1.20:6379' #修改成自己的ip和port
3. 修改爬虫代码
- 使爬虫继承自RedisSpider
from scrapy_redis.spiders import RedisSpider
class DoubanSpider(RedisSpider):
- 增加一个
redis_key属性，这个属性就是start_urls在redis中的key - 注释掉
start_urls
#!/usr/bin/python3
# -*- coding: utf-8 -*-
import scrapy
from scrapy import Request
from project_douban.items import Movie
from scrapy_redis.spiders import RedisSpider
class DoubanSpider(RedisSpider):
name = 'douban'
allowed_domains = ['douban.com']
redis_key = "doubanSpider:start_urls"
#start_urls = ['https://movie.douban.com/top250']
headers = {
'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
'Accept-Language': 'en',
'User-Agent' : 'Mozilla/5.0 (Linux; Android 8.0; Pixel 2 Build/OPD3.170816.012) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.139 Mobile Safari/537.36',
}
custom_settings = {
'DEFAULT_REQUEST_HEADERS' : headers,
'REDIRECT_ENABLED' : 'False',
#'LOG_LEVEL' : 'WARNING',
}
def parse(self, response):
items = response.xpath('//div[@class="item"]')
for item in items:
movie = Movie()
movie['index'] = item.xpath('div//em/text()').extract_first(default = '')
self.logger.info(movie['index'])
movie['src'] = item.xpath('div//img/@src').extract_first(default = '')
self.logger.info(movie['src'])
movie['title'] = item.xpath('.//div[@class="hd"]/a/span[1]/text()').extract_first(default = '') #.xpath('string(.)').extract()).replace(' ','').replace('\xa0',' ').replace('\n',' ')
self.logger.info(movie['title'])
movie['star'] = item.xpath('.//span[@class="rating_num"]/text()').extract_first(default = '')
self.logger.info(movie['star'])
movie['info'] = item.xpath('.//div[@class="bd"]/p').xpath('string(.)').extract_first(default = '').strip().replace(' ','').replace('\xa0',' ').replace('\n',' ')
self.logger.info(movie['info'])
yield movie
next_url = response.xpath('//span[@class="next"]/a/@href').extract_first(default = '')
self.logger.info('next_url: ' + next_url)
if next_url:
next_url = 'https://movie.douban.com/top250' + next_url
yield Request(next_url, headers = self.headers)
- log写入文件（optional)
import logging
import os
import time
def get_logger(name, start_time = time.strftime('%Y_%m_%d_%H', time.localtime())):
path = '/var/log/scrapy-redis/'
# path = 'baidu_tieba.log'
if not os.path.exists(path):
os.makedirs(path)
log_path = path + start_time
# 创建一个logger
my_logger = logging.getLogger(name)
my_logger.setLevel(logging.INFO)
formatter = logging.Formatter('[%(asctime)s] [%(levelname)s] %(filename)s[line:%(lineno)d] %(message)s', datefmt = '%Y-%m-%d %H:%M:%S')
# 创建handler，用于写入日志文件
handler_info = logging.FileHandler('%s_info.log' % log_path, 'a', encoding='UTF-8')
handler_info.setLevel(logging.INFO)
handler_info.setFormatter(formatter)
my_logger.addHandler(handler_info)
handler_warning = logging.FileHandler('%s_warning.log' % log_path, 'a', encoding='UTF-8')
handler_warning.setLevel(logging.WARNING)
handler_warning.setFormatter(formatter)
my_logger.addHandler(handler_warning)
handler_error = logging.FileHandler('%s_error.log' % log_path, 'a', encoding='UTF-8')
handler_error.setLevel(logging.ERROR)
handler_error.setFormatter(formatter)
my_logger.addHandler(handler_error)
return my_logger
Miscellaneous
RedisSpider vs RedisCrawlSpider
直接看源代码，上文本比较
| item | RedisSpider | RedisCrawlSpider |
|---|---|---|
| REDIS_START_URLS_AS_SET | default: False | default: True |
| 继承自Spider | 继承自CrawlSpider |
scrapy.Spider -> scrapy.CrawlSpider
scrapy.Spider是所有爬虫的基类, scrapy.CrawlSpider基于scrapy.Spider, 增加了rules, 可以设置某种规则，只爬取满足这些规则的网页, RedisCrawlSpider也继承了这一特性
