centos6.8安装python3.7.3报错Can't connect to HTTPS URL because the SSL module is not available问题解决

环境：CentOS release 6.8 (Final)

# 直接编译python3.7在使用pip3安装依赖的时候报错：

Can't connect to HTTPS URL because the SSL module is not available.

解决方法：

.编译安装OpenSSL 1.0.2j版本并重新配置环境变量

下载OpenSSL源码包：
wget http://www.openssl.org/source/openssl-1.0.2j.tar.gz

解压缩，编译安装：
tar -zxvf openssl-1.0.2j.tar.gz
cd openssl-1.0.2j
./config --prefix=/usr/local/lab/openssl-1.0.2j shared zlib
make && make install

.编译安装Python3,使用自定义的OpenSSL

下载Python3..3源码包：

wget https://www.python.org/ftp/python/3.7.3/Python-3.7.3.tgz

解压缩，编译安装：

tar -zxvf Python-3.7..tgz
cd Python-3.7.
./configure --prefix=/usr/local/python373

在这一步之后，先不要着急运行make命令。先修改源码目录 Python-3.7./Modules/Setup 文件：

# Socket module helper for socket()
#_socket socketmodule.c

# Socket module helper for SSL support; you must comment out the other
# socket line above, and possibly edit the SSL variable:
SSL=/usr/local/lab/openssl-1.0.2j/    #取消这一行的注释，并将原来的/usr/local/ssl改为我们新安装的openssl目录：/usr/local/lab/openssl-1.0.2j/
_ssl _ssl.c \     #取消这一行的注释
-DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \      #取消这一行的注释
-L$(SSL)/lib -lssl -lcrypto      #取消这一行的注释

# The crypt module is now disabled by default because it breaks builds
# on many systems (where -lcrypt is needed), e.g. Linux (I believe).

#_crypt _cryptmodule.c # -lcrypt    # crypt(); needs -lcrypt on some systems

修改完成以后，还需要创建两个指向动态链接库的软链接文件：
ln -s /usr/local/lab/openssl-1.0.2j/lib/libssl.so.1.0. /usr/lib64/libssl.so.1.0.
ln -s /usr/local/lab/openssl-1.0.2j/lib/libcrypto.so.1.0. /usr/lib64/libcrypto.so.1.0.

最后编译并安装：
make && make install

# 创建软连接
ln -s /usr/local/python373/bin/pip3 /usr/local/bin/pip3
ln -s /usr/local/python373/bin/python3 /usr/local/bin/python3

# 安装软件继续报错：
[root@srv3:/usr/local]# pip3 install requests
Collecting requests
/usr/local/python373/bin/python3.: symbol lookup error: /usr/local/python373/bin/python3.: undefined symbol: SSL_CTX_get0_param

# 找了各自资料发现都无法解决这个问题，问题很可能就出在openssl上

undefined symbol: SSL_CTX_get0_param 这个函数就是zlib源码中的函数，于是重新编译openssl

.清理之前安装的openssl
rm -rf /usr/local/src/openssl-1.0.2j    # 清理源码
rm -rf /usr/local/lab/openssl-1.0.2j    # 清理安装程序

tar -zxvf openssl-1.0.2j.tar.gz
cd openssl-1.0.2j
# 修改编译参数，no-zlib 不需要zlib
./config --prefix=/usr/local/lab/openssl-1.0.2j no-zlib
make && make install

.重新编译安装Python3.7.3

# 清理源码目录和已经按照的目录
rm -rf /usr/local/src/Python-3.7.
rm -rf /usr/local/python373

# 再次解压编译安装
tar -zxvf Python-3.7..tgz
cd Python-3.7.
./configure --prefix=/usr/local/python373

在这一步之后，先不要着急运行make命令，先修改源码目录 Python-3.7./Modules/Setup 文件：

# Socket module helper for socket()
#_socket socketmodule.c

# Socket module helper for SSL support; you must comment out the other
# socket line above, and possibly edit the SSL variable:
SSL=/usr/local/lab/openssl-1.0.2j/    #取消这一行的注释，并将原来的/usr/local/ssl改为我们新安装的openssl目录：/usr/local/lab/openssl-1.0.2j/
_ssl _ssl.c \     #取消这一行的注释
-DUSE_SSL -I$(SSL)/include -I$(SSL)/include/openssl \      #取消这一行的注释
-L$(SSL)/lib -lssl -lcrypto      #取消这一行的注释

# The crypt module is now disabled by default because it breaks builds
# on many systems (where -lcrypt is needed), e.g. Linux (I believe).

#_crypt _cryptmodule.c # -lcrypt    # crypt(); needs -lcrypt on some systems

最后编译并安装：
make && make install

# 再次pip3安装依赖就不会报错了
[root@srv3:/usr/local/src/Python-3.7.]# pip3 install requests
Collecting requests
  Downloading https://files.pythonhosted.org/packages/51/bd/23c926cd341ea6b7dd0b2a00aba99ae0f828be89d72b2190f27c11d4b7fb/requests-2.22.0-py2.py3-none-any.whl (57kB)
    % |████████████████████████████████| 61kB .1MB/s
Collecting certifi>=2017.4. (from requests)
  Downloading https://files.pythonhosted.org/packages/69/1b/b853c7a9d4f6a6d00749e94eb6f3a041e342a885b87340b79c1ef73e3a78/certifi-2019.6.16-py2.py3-none-any.whl (157kB)
    % |████████████████████████████████| 163kB .3MB/s
Collecting idna<2.9,>=2.5 (from requests)
  Downloading https://files.pythonhosted.org/packages/14/2c/cd551d81dbe15200be1cf41cd03869a46fe7226e7450af7a6545bfc474c9/idna-2.8-py2.py3-none-any.whl (58kB)
    % |████████████████████████████████| 61kB .8MB/s
Collecting chardet<3.1.,>=3.0. (from requests)
  Downloading https://files.pythonhosted.org/packages/bc/a9/01ffebfb562e4274b6487b4bb1ddec7ca55ec7510b22e4c51f14098443b8/chardet-3.0.4-py2.py3-none-any.whl (133kB)
    % |████████████████████████████████| 143kB .9MB/s
Collecting urllib3!=1.25.,!=1.25.,<1.26,>=1.21. (from requests)
  Downloading https://files.pythonhosted.org/packages/e6/60/247f23a7121ae632d62811ba7f273d0e58972d75e58a94d329d51550a47d/urllib3-1.25.3-py2.py3-none-any.whl (150kB)
    % |████████████████████████████████| 153kB .8MB/s
Installing collected packages: certifi, idna, chardet, urllib3, requests
Successfully installed certifi-2019.6. chardet-3.0. idna-2.8 requests-2.22. urllib3-1.25.