问题解决： pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.

问题描述：执行pip install pykafka命令时出现

pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Collecting pykafka
  Could not fetch URL https://pypi.python.org/simple/pykafka/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
  Could not find a version that satisfies the requirement pykafka (from versions: )
No matching distribution found for pykafka

　问题解决：

在./configure过程中，如果没有加上–with-ssl参数时，默认安装的软件涉及到ssl的功能不可用，
刚好pip3过程需要ssl模块，而由于没有指定，所以该功能不可用。

查看openssl安装包，发现缺少openssl-devel包 

1. 查看openssl安装包，发现缺少openssl-devel包 
   [root@localhost ~]# rpm -aq|grep openssl 
   openssl-0.9.8e-20.el5 
   openssl-0.9.8e-20.el5 
   [root@localhost ~]#

2. yum安装openssl-devel 
   [root@localhost ~]# yum install openssl-devel -y 
   查看安装结果 
   [root@localhost ~]# rpm -aq|grep openssl 
   openssl-0.9.8e-26.el5_9.1 
   openssl-0.9.8e-26.el5_9.1 
   openssl-devel-0.9.8e-26.el5_9.1 
   openssl-devel-0.9.8e-26.el5_9.1

3. 重新对python3.6进行编译安装，用一下过程来实现编译安装:

   cd Python-3.6.4
   ./configure --with-ssl
   make
   sudo make install

重新运行pip install pykafka时，又出现此提示;

You are using pip version 9.0.1, however version 19.2.2 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

运行

pip install --upgrade pip