Installing a gem of rails need sodo password

I need to install gem "gdk_pixbuf2" but on doing "bundle install" its asking me for SUDO password which webfaction doesn't provide even though I'm logged in with my root user.

This is what I get when I'm trying to install this gem :

    Installing gdk_pixbuf2 (2.0.2) [sudo] password for ****** to install <gtk2-devel>:
Now the problem is I don't have the password And after that I'm getting this error:

Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

    /usr/local/bin/ruby2.0 extconf.rb 
checking for -Wall option to compiler... yes
checking for -Waggregate-return option to compiler... yes
checking for -Wcast-align option to compiler... yes
checking for -Wextra option to compiler... yes
checking for -Wformat=2 option to compiler... yes
checking for -Winit-self option to compiler... yes
checking for -Wlarger-than-65500 option to compiler... yes
checking for -Wmissing-declarations option to compiler... yes
checking for -Wmissing-format-attribute option to compiler... yes
checking for -Wmissing-include-dirs option to compiler... yes
checking for -Wmissing-noreturn option to compiler... yes
checking for -Wmissing-prototypes option to compiler... yes
checking for -Wnested-externs option to compiler... yes
checking for -Wold-style-definition option to compiler... yes
checking for -Wpacked option to compiler... yes
checking for -Wp,-D_FORTIFY_SOURCE=2 option to compiler... yes
checking for -Wpointer-arith option to compiler... yes
checking for -Wswitch-default option to compiler... yes
checking for -Wswitch-enum option to compiler... yes
checking for -Wundef option to compiler... yes
checking for -Wunsafe-loop-optimizations option to compiler... yes
checking for -Wwrite-strings option to compiler... yes
checking for rb_define_alloc_func() in ruby.h... yes
checking for rb_block_proc() in ruby.h... yes
checking for new allocation framework... yes
checking for attribute assignment... no
checking for Win32 OS... no
checking for gdk-pixbuf-2.0... no
checking for sudo... yes
installing 'gtk2-devel' native package... failed
failed to run '/usr/bin/sudo -p \[sudo\]\ password\ for\ \%u\ to\ install\ \<gtk2-devel\>:\  yum install -y gtk2-devel'.
*** 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/ruby20
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/local/bin/ruby2.0
    --with-pkg-config
    --without-pkg-config
    --with-override-variables
    --without-override-variables

Gem files will remain installed in ******************** for inspection.
Results logged to *******

An error occurred while installing gdk_pixbuf2 (2.0.2), and Bundler cannot
continue.
Make sure that `gem install gdk_pixbuf2 -v '2.0.2'` succeeds before bundling.