PostgreSQL ruby gem installation issue

Question

I have some troubles with installing my Postgres gem. When I run:

 gem install pg -v '0.19.0'

it prints:

Successfully installed pg-0.19.0
Parsing documentation for pg-0.19.0
Done installing documentation for pg after 2 seconds
1 gem installed

but when I run:

bundle install

it stops on the pg gem and prints:

An error occurred while installing pg (0.19.0), and Bundler cannot continue.
Make sure that `gem install pg -v '0.19.0'` succeeds before bundling.

The whole log is:

sh: /usr/pgsql-9.1/bin/pg_config: No such file or directory
sh: /usr/pgsql-9.1/bin/pg_config: No such file or directory
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.

gem env outputs:

/ruby/2.3.0/rubygems/commands/environment_command.rb:154: warning: Insecure world writable dir /usr/local/bin in PATH, mode 040777
RubyGems Environment:
  - RUBYGEMS VERSION: 2.5.1
  - RUBY VERSION: 2.3.0 (2015-12-25 patchlevel 0) [x86_64-darwin16]
  - INSTALLATION DIRECTORY: /.rvm/gems/ruby-2.3.0
  - USER INSTALLATION DIRECTORY: /.gem/ruby/2.3.0
  - RUBY EXECUTABLE: /.rvm/rubies/ruby-2.3.0/bin/ruby
  - EXECUTABLE DIRECTORY: /.rvm/gems/ruby-2.3.0/bin
  - SPEC CACHE DIRECTORY: /.gem/specs
  - SYSTEM CONFIGURATION DIRECTORY: /.rvm/rubies/ruby-2.3.0/etc
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-darwin-16
  - GEM PATHS:
     - /.rvm/gems/ruby-2.3.0
     - /.rvm/gems/ruby-2.3.0@global
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - https://rubygems.org/
  - SHELL PATH:
     - /.rvm/gems/ruby-2.3.0/bin
     - /.rvm/gems/ruby-2.3.0@global/bin
     - /.rvm/rubies/ruby-2.3.0/bin
     - /.rvm/bin
     - /usr/local/bin
     - /usr/bin
     - /bin
     - /usr/sbin
     - /sbin

Answer 1

I'm surprised that gem installed pg without it knowing where your PostgreSQL is installed.

The error messages

sh: /usr/pgsql-9.1/bin/pg_config: No such file or directory
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header

are the result of the code not being able to locate the headers, which are the result of not finding pg_config .

The simple fix is to temporarily update your PATH with the directory containing pg_config . You can do that easily using locate :

locate pg_config

On my system that returns:

/Applications/Postgres.app/Contents/Versions/9.5/bin/pg_config

among other things. The pg_config you want will be in the bin directory for whichever PostgreSQL you want to use with Ruby.

If you don't have locate running you could also do:

find / -name pg_config -type f 2>/dev/null

and wait while find searches your drive. (Having locate available to you is very helpful, so if it's not running I'd suggest starting it.)

Modify your PATH with the path to pg_config then run your commands:

PATH=/Applications/Postgres.app/Contents/Versions/9.5/bin:$PATH gem install pg && bundle install

Modify the path to pg_config for your system of course.

It might also work to remove gem install pg && and simply run the bundle install .