問題解決： pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.

問題描述：執行pip install pykafka命令時出現

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

　問題解決：

在./configure過程中，如果沒有加上–with-ssl參數時，默認安裝的軟件涉及到ssl的功能不可用，
剛好pip3過程需要ssl模塊，而由於沒有指定，所以該功能不可用。

查看openssl安裝包，發現缺少openssl-devel包 

1. 查看openssl安裝包，發現缺少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安裝openssl-devel 
   [root@localhost ~]# yum install openssl-devel -y 
   查看安裝結果 
   [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. 重新對python3.6進行編譯安裝，用一下過程來實現編譯安裝:

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

重新運行pip install pykafka時，又出現此提示;

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.

運行

pip install --upgrade pip