pip安装软件报错 SSL: CERTIFICATE_VERIFY_FAILED

pip安装软件报错提示SSL: CERTIFICATE_VERIFY_FAILED

使用pip安装组件时，突然失败：

$ pip install ${组件名}
Collecting ${组件名}
  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)': /simple/xxx/
  Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)': /simple/xxx/
  Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)': /simple/xxx/
  Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)': /simple/xxx/
  Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)': /simple/xxx/
  Could not fetch URL https://pypi.org/simple/xxx/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/xxx/ (Caused by SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:726)'),)) - skipping
  Could not find a version that satisfies the requirement xxx (from versions: )
No matching distribution found for xxx

解决办法

在pip命令行中增加–trusted-host pypi.python.org选项

$ pip install ${组件名} --trusted-host pypi.python.org

问题解决！