Build Gem Native Extension - linux

Question

Passing on knowledge I just learned in the hopes of reducing the
headache others may experience with native gem extensions like I've
had.
TL;DR - Had an issue with bundle install. Read mkmf.log as mentioned in the error. The log had another error that I googled. Installed
necessary library. Afterwards, bundle install was successful.
Trying to install gems using bundler and getting errors about building gem native extensions:
$ bundle install
Fetching gem metadata from https://rubygems.org/...........
Fetching version metadata from https://rubygems.org/..
Resolving dependencies...
Installing daemons 1.2.3
Installing eventmachine 1.0.8 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.0/gems/eventmachine-1.0.8/ext
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -r ./siteconf20160309-8483-1so3k75.rb extconf.rb
*** 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.
<...>
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/usr/local/rvm/gems/ruby-2.3.0/extensions/x86_64-linux/2.3.0/eventmachine-1.0.8/mkmf.log
extconf failed, exit code 1
<...>
Installing mysql2 0.4.3 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /usr/local/rvm/gems/ruby-2.3.0/gems/mysql2-0.4.3/ext/mysql2
/usr/local/rvm/rubies/ruby-2.3.0/bin/ruby -r ./siteconf20160309-8483-1oxfnj5.rb extconf.rb
checking for ruby/thread.h... *** 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.
<...>
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/usr/local/rvm/gems/ruby-2.3.0/extensions/x86_64-linux/2.3.0/mysql2-0.4.3/mkmf.log
extconf failed, exit code 1
<...>
Installing rack 1.6.4
Installing tilt 2.0.1
Using bundler 1.11.2
An error occurred while installing eventmachine (1.0.8), and Bundler cannot continue.
Make sure that `gem install eventmachine -v '1.0.8'` succeeds before bundling.

Answer 1

Passing on knowledge I just learned in the hopes of reducing the
headache others may experience with native gem extensions like I've
had.
TL;DR - Had an issue with bundle install. Read mkmf.log as mentioned in the error. The log had another error that I googled. Installed
necessary library. Afterwards, bundle install was successful.
I see that the errors point me to mkmf.log and where it's located. I open it up and check the error. Among other things it mentions the following on lines 2 and 3.
/usr/bin/ld: cannot find -lgmp
collect2: error: ld returned 1 exit status
I know from the error while during bundle install that it could be missing a library. So I search for a package called gmp. I find 2 libraries, one called libgmp10 and the other libgmp10-dev.
$ apt-cache search -n gmp
libgmp-dev - Multiprecision arithmetic library developers tools
libgmp10 - Multiprecision arithmetic library
<...>
I search my installed packages to see if I need to get one.
$ dpkg --get-selections | grep gmp
libgmp10:amd64 install
Since libgmp10 is already there, I try installing libgmp-dev. Then I run retry installing my gems, and it works!
$ sudo apt-get install libgmp-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
libgmpxx4ldbl
Suggested packages:
libgmp10-doc libmpfr-dev
The following NEW packages will be installed:
libgmp-dev libgmpxx4ldbl
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 300 kB of archives.
After this operation, 1,675 kB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://us.archive.ubuntu.com/ubuntu/ trusty/main libgmpxx4ldbl amd64 2:5.1.3+dfsg-1ubuntu1 [8,736 B]
Get:2 http://us.archive.ubuntu.com/ubuntu/ trusty/main libgmp-dev amd64 2:5.1.3+dfsg-1ubuntu1 [292 kB]
Fetched 300 kB in 0s (411 kB/s)
Selecting previously unselected package libgmpxx4ldbl:amd64.
(Reading database ... 218685 files and directories currently installed.)
Preparing to unpack .../libgmpxx4ldbl_2%3a5.1.3+dfsg-1ubuntu1_amd64.deb ...
Unpacking libgmpxx4ldbl:amd64 (2:5.1.3+dfsg-1ubuntu1) ...
Selecting previously unselected package libgmp-dev:amd64.
Preparing to unpack .../libgmp-dev_2%3a5.1.3+dfsg-1ubuntu1_amd64.deb ...
Unpacking libgmp-dev:amd64 (2:5.1.3+dfsg-1ubuntu1) ...
Setting up libgmpxx4ldbl:amd64 (2:5.1.3+dfsg-1ubuntu1) ...
Setting up libgmp-dev:amd64 (2:5.1.3+dfsg-1ubuntu1) ...
Processing triggers for libc-bin (2.19-0ubuntu6.7) ...
$ bundle install
Fetching gem metadata from https://rubygems.org/...........
Fetching version metadata from https://rubygems.org/..
Resolving dependencies...
Using daemons 1.2.3
Installing eventmachine 1.0.8 with native extensions
Installing mysql2 0.4.3 with native extensions
Using rack 1.6.4
Using tilt 2.0.1
Using bundler 1.11.2
Installing rack-protection 1.5.3
Installing thin 1.6.4 with native extensions
Installing sinatra 1.4.6
Bundle complete! 3 Gemfile dependencies, 9 gems now installed.
Use `bundle show [gemname]` to see where a bundled gem is installed.