gem install Unable to download data from https://rubygems.org/

problem:

   root@gitlab:~# gem install bundler --no-ri --no-rdoc
ERROR:  Could not find a valid gem 'bundler' (>= 0), here is why:
          Unable to download data from https://rubygems.org/ - Errno::ECONNRESET: Connection reset by peer - SSL_connect (https://rubygems.org/latest_specs.4.8.gz)

solution:  used --source option to specify the http protocol not https.

  root@gitlab:~# gem install bundler --no-ri --no-rdoc --source http://rubygems.org
Fetching: bundler-1.10.6.gem (100%)
Successfully installed bundler-1.10.6
WARNING:  Unable to pull data from 'https://rubygems.org/': Errno::ECONNRESET: Connection reset by peer - SSL_connect (https://rubygems.org/latest_specs.4.8.gz)
1 gem installed
root@gitlab:~#