centos 下安装scrapy过程及遇到的问题

问题：

1. centos6.6下自带安装的是python2.6.6（yum使用不了python2.7），而我们使用scrapy需要使用的是python2.7，因此会有一些麻烦，幸运的是在python2.6.6和python2.7是可以共存的。

vim /usr/bin/scarpy 去修改首行的内容，改为python2.7的路径（我的是/usr/local/bin/Python2.7），或者使用软链接。

2.No package 'libffi' found ——》pkg_resources.DistributionNotFound:
cryptography>=0.2.1

对于这个问题google更准备的给出了答案。（/article/11334774.html）

1 安装好的 scrapy 运行出现

pkg_resources.DistributionNotFound: cryptography>=0.2.1 于是 运行

easy_install cryptography 但是报 No package 'libffi' found错误

2 检查 yum install libffi 但是提示 libffi 已经安装

3 由于 easy_install cryptography是编译安装 所以 需要libffi-devel

运行 yum install libffi-devel 按照后 再运行 easy_install cryptography就可以顺利通过了。

具体安装流程：

Centos下安装Scrapy（转自/article/5507399.html）

Scrapy是一个开源的机遇twisted框架的python的单机爬虫，该爬虫实际上包含大多数网页抓取的工具包，用于爬虫下载端以及抽取端。
安装环境:

centos6.6
python2.7.3

安装步骤:
1.下载python2.7 http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz

[root@zxy-websgs ~]# wget http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz -P /opt

[root@zxy-websgs opt]# tar xvf Python-2.7.3.tgz

[root@zxy-websgs Python-2.7.3]# ./configure

[root@zxy-websgs Python-2.7.3]# make && make install

　验证python2.7安装

[root@zxy-websgs Python-2.7.3]# python2.7
Python 2.7.3 (default, Feb 28 2013, 03:08:43)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-50)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()

2.安装setuptools,http://pypi.python.org/packages/source/s/setuptools/setuptools-0.6c11.tar.gz

[root@zxy-websgs ~]# wget http://pypi.python.org/packages/source/s/setuptools/setuptools-0.6c11.tar.gz -P /opt/
[root@zxy-websgs opt]# tar zxvf setuptools-0.6c11.tar.gz
[root@zxy-websgs setuptools-0.6c11]# python2.7 setup.py  install

3.安装Twisted

[root@zxy-websgs setuptools-0.6c11]# easy_install Twisted
......
Installed /usr/local/lib/python2.7/site-packages/Twisted-12.3.0-py2.7-linux-x86_64.egg
......
Installed /usr/local/lib/python2.7/site-packages/zope.interface-4.0.4-py2.7-linux-x86_64.egg

Twisted要安装zope.interface,可以从下面地址下载
zope.interface:http://pypi.python.org/packages/source/z/zope.interface/zope.interface-4.0.1.tar.gz
twisted:http://twistedmatrix.com/Releases/Twisted/12.1/Twisted-12.1.0.tar.bz2
5.安装w3lib

[root@zxy-websgs setuptools-0.6c11]# easy_install -U w3lib
Searching for w3lib
Reading http://pypi.python.org/simple/w3lib/ Reading http://github.com/scrapy/w3lib Best match: w3lib 1.2
Downloading http://pypi.python.org/packages/source/w/w3lib/w3lib-1.2.tar.gz#md5=f929d5973a9fda59587b09a72f185a9e Processing w3lib-1.2.tar.gz
Running w3lib-1.2/setup.py -q bdist_egg --dist-dir /tmp/easy_install-wm_1BB/w3lib-1.2/egg-dist-tmp-2DQHY_
zip_safe flag not set; analyzing archive contents...
Adding w3lib 1.2 to easy-install.pth file

Installed /usr/local/lib/python2.7/site-packages/w3lib-1.2-py2.7.egg
Processing dependencies for w3lib
Finished processing dependencies for w3lib

w3lib:http://pypi.python.org/packages/source/w/w3lib/w3lib-1.2.tar.gz
6.安装libxml2或者用easy_install安装lxml

[root@zxy-websgs lxml-3.1.0]# easy_install lxml

验证lxml安装

[root@zxy-websgs lxml-3.1.0]# python2.7
Python 2.7.3 (default, Feb 28 2013, 03:08:43)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-50)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import lxml
>>> exit()

也可以安装libxml2,官网上推荐安装2.6.28或者以上的版本，但在官网上没找到，我先是安装的2.6.9的版本，运行scrapy时报以下错误

Traceback (most recent call last):
File "/usr/local/bin/scrapy", line 5, in <module>
pkg_resources.run_script('Scrapy==0.14.4', 'scrapy')
File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 489, in run_script
File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 1207, in run_script
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/EGG-INFO/scripts/scrapy", line 4, in <module>
execute()
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/cmdline.py", line 112, in execute
cmds = _get_commands_dict(inproject)
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/cmdline.py", line 37, in _get_commands_dict
cmds = _get_commands_from_module('scrapy.commands', inproject)
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/cmdline.py", line 30, in _get_commands_from_module
for cmd in _iter_command_classes(module):
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/cmdline.py", line 21, in _iter_command_classes
for module in walk_modules(module_name):
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/utils/misc.py", line 65, in walk_modules
submod = __import__(fullpath, {}, {}, [''])
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/commands/shell.py", line 8, in <module>
from scrapy.shell import Shell
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/shell.py", line 14, in <module>
from scrapy.selector import XPathSelector, XmlXPathSelector, HtmlXPathSelector
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/selector/__init__.py", line 30, in <module>
from scrapy.selector.libxml2sel import *
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/selector/libxml2sel.py", line 12, in <module>
from .factories import xmlDoc_from_html, xmlDoc_from_xml
File "/usr/local/lib/python2.7/site-packages/Scrapy-0.14.4-py2.7.egg/scrapy/selector/factories.py", line 14, in <module>
libxml2.HTML_PARSE_NOERROR + \
AttributeError: 'module' object has no attribute 'HTML_PARSE_RECOVER'

升级到2.6.21版本以后解决了。
libxml2.6.1:ftp://xmlsoft.org/libxml2/python/libxml2-python-2.6.21.tar.gz
7.安装pyOpenSSL(这个是可选安装的，主要为了使scrapy能够支持https)
用easy_install pyOpenSSL安装的是pyOpenSSL-0.13版本，没安装成功，于是手动下载.011版本来进行安装。

[root@zxy-websgs opt]# wget http://launchpadlibrarian.net/58498441/pyOpenSSL-0.11.tar.gz -P /opt
[root@zxy-websgs opt]# tar zxvf pyOpenSSL-0.11.tar.gz
[root@zxy-websgs pyOpenSSL-0.11]# python2.7 setup.py install

pyOpenSSL:http://launchpadlibrarian.net/58498441/pyOpenSSL-0.11.tar.gz
8.安装scrapy

[root@zxy-websgs pyOpenSSL-0.11]# easy_install -U Scrapy

验证安装

[root@zxy-websgs pyOpenSSL-0.11]# scrapy
Scrapy 0.16.4 - no active project

Usage:
scrapy <command> [options] [args]

Available commands:
fetch         Fetch a URL using the Scrapy downloader
runspider     Run a self-contained spider (without creating a project)
settings      Get settings values
shell         Interactive scraping console
startproject  Create new project
version       Print Scrapy version
view          Open URL in browser, as seen by Scrapy

[ more ]      More commands available when run from project directory

Use "scrapy <command> -h" to see more info about a command

scrapy:http://pypi.python.org/packages/source/S/Scrapy/Scrapy-0.14.4.tar.gz
总结：
pyOpenSSL单独安装的时候不成功，也可以先下载pyOpenSSL0.11进行安装，再使用easy_install -U Scrapy进行全程安装