While bundling an old project, this error came up:
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/home/dd/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb
checking for curl-config... no
checking for main() in -lcurl... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/home/dd/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
--with-curl-dir
--without-curl-dir
--with-curl-include
--without-curl-include=${curl-dir}/include
--with-curl-lib
--without-curl-lib=${curl-dir}/
--with-curllib
--without-curllib
extconf.rb:18:in `<main>': Can't find libcurl or curl/curl.h (RuntimeError)
Try passing --with-curl-dir or --with-curl-lib and --with-curl-include
options to extconf.
Gem files will remain installed in /home/dd/.rvm/gems/ruby-2.0.0-p247/gems/curb-0.8.5 for inspection.
Results logged to /home/dd/.rvm/gems/ruby-2.0.0-p247/gems/curb-0.8.5/ext/gem_make.out
An error occurred while installing curb (0.8.5), and Bundler cannot continue.
Make sure that `gem install curb -v '0.8.5'` succeeds before bundling.
I found the solution here
sudo apt-get install libcurl3-dev