Why can't the pg gem be installed in AWS Elastic Beanstalk?

Question

I am deploying a simple application to AWS Elastic Beanstalk. However, the moment I put gem 'pg' in the Gemfile and push these to Elastic Beanstalk. I get the following errors in my logs:

-------------------------------------
/var/log/eb-tools.log
-------------------------------------
Installing actionpack (4.0.1) 
Installing mime-types (1.25) 
Installing polyglot (0.3.3) 
Installing treetop (1.4.15) 
Installing mail (2.5.4) 
Installing actionmailer (4.0.1) 
Installing activemodel (4.0.1) 
Installing activerecord-deprecated_finders (1.0.3) 
Installing arel (4.0.1) 
Installing activerecord (4.0.1) 
Installing coffee-script-source (1.6.3) 
Installing execjs (2.0.2) 
Installing coffee-script (2.2.0) 
Installing thor (0.18.1) 
Installing railties (4.0.1) 
Installing coffee-rails (4.0.1) 
Installing hike (1.2.3) 
Installing jbuilder (1.5.2) 
Installing jquery-rails (3.0.4) 
Using json (1.8.1) 
Installing pg (0.17.0) 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9 extconf.rb 
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
 --with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** 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}/
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/bin/ruby1.9
    --with-pg
    --without-pg
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/


Gem files will remain installed in /usr/share/ruby/1.9/gems/1.9.1/gems/pg-0.17.0 for inspection.
Results logged to /usr/share/ruby/1.9/gems/1.9.1/gems/pg-0.17.0/ext/gem_make.out
An error occurred while installing pg (0.17.0), and Bundler cannot continue.
Make sure that `gem install pg -v '0.17.0'` succeeds before bundling.
ERROR: bundle install failed!

2013-11-17 14:10:03,371 [ERROR] (8302 MainThread) [directoryHooksExecutor.py-34] [root directoryHooksExecutor error] Script failed with returncode 1
2013-11-17 14:10:03,499 [INFO] (8269 MainThread) [command.py-130] [root command execute] Command returned: (code: 1, stdout: Error occurred during build: Command hooks failed
, stderr: None)
....

I get no errors locally.

Quite some time ago, I remember encountering this problem on my other Ubuntu boxes. Apparently, one needs to install additional libraries via sudo apt-get install ruby-dev build-essential or sudo apt-get install postgresql-client libpq5 libpq-dev. I would give it a shot, but On AWS Elastic Beanstalk, I am not so sure how to do this.

Answer 1

In .ebextensions/packages.config:

packages:
  yum:
    postgresql-devel: []

This will ensure any new instances will have this lib installed

Answer 2

add

packages:
  yum:
    postgresql93-devel: []

Answer 3

In .ebextensions/packages.config

packages:
  yum:
    postgresql-devel: []

The important thing to note is that you need to set postgresql-devel to match the lib for your postgresql version. e.g., if you have postgresql 9.4.5 you need to install a postgresql-develXX.

Using yum list you will be able to identify the correct lib.