AWS CodeBuild process for Rails fails to install pg gem

Question

I am trying to deploy Rails to Elastic Beanstalk using a simple 3-step CodePipeline process. Step 1 takes the source from GitHub, gives it to CodeBuild, which then should create the build and pass it to EB.

For some reason, when the CodeBuild process reaches the pg gem, it fails with the following error:

Fetching pg 1.3.5
Installing pg 1.3.5 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/root/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/pg-1.3.5/ext
/root/.rbenv/versions/2.7.2/bin/ruby -I
/root/.rbenv/versions/2.7.2/lib/ruby/2.7.0 -r ./siteconf20220419-56-10cqcfm.rb
extconf.rb
Calling libpq with GVL unlocked
checking for pg_config... yes
Using config values from /usr/bin/pg_config
Using libpq from /usr/lib64
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for pg_config_manual.h... yes
checking for PQconnectdb() in -lpq... yes
checking for PQconninfo() in libpq-fe.h... no
Your PostgreSQL is too old. Either install an older version of this gem or
upgrade your database to at least PostgreSQL-9.3.
*** 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=/root/.rbenv/versions/2.7.2/bin/$(RUBY_BASE_NAME)
    --with-pg
    --without-pg
    --enable-gvl-unlock
    --disable-gvl-unlock
    --enable-windows-cross
    --disable-windows-cross
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pq-dir
    --without-pq-dir
    --with-pq-include
    --without-pq-include=${pq-dir}/include
    --with-pq-lib
    --without-pq-lib=${pq-dir}/lib
    --with-pqlib
    --without-pqlib

To see why this extension failed to compile, please check the mkmf.log which can
be found here:

/root/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0/pg-1.3.5/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in
/root/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/pg-1.3.5 for inspection.
Results logged to
/root/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/extensions/x86_64-linux/2.7.0/pg-1.3.5/gem_make.out

An error occurred while installing pg (1.3.5), and Bundler cannot continue.
Make sure that `gem install pg -v '1.3.5' --source 'https://rubygems.org/'`
succeeds before bundling.

In Gemfile:
  pg

[Container] 2022/04/19 14:56:37 Command did not exit successfully bundle install exit status 5
[Container] 2022/04/19 14:56:37 Phase complete: INSTALL State: FAILED
[Container] 2022/04/19 14:56:37 Phase context status code: COMMAND_EXECUTION_ERROR Message: Error while executing command: bundle install. Reason: exit status 5

I have the following barebones buildspec.yml:

version: 0.2

phases:
  install:
    commands: 
      - bundle install
artifacts:
  files:
    - '**/*'

The bundle process runs without error on my local machine.

Answer 1

I had the same problem you had above too (except without using CodeBuild). The issue is that you're trying to install the pg gem at version 1.3.5. At the time of writing, Elastic Beanstalk on Amazon Linux 2 (AL2) ships with Postgres version 9.2 by default (incredibly old 😔). Whereas the pg gem dropped support for 9.2 after version 1.2.3. See here.

So your 2 options are either:

1. Enhance EB to install a more recent version of Postgres during the build & deploy process, for example as described here: https://stackoverflow.com/a/63204453/1852005.
2. Or you could just use version 1.2.3 of the pg gem by configuring that version in your Gemfile. That version shipped in 2020-03-18.

Either of those options should get you past that error.

Note that your application may also connect to Amazon's RDS which has a more recent Postgres version. However that RDS lives on another server, so don't get the two confused! You can see the difference if you eb ssh to the server and run e.g: this on the shell directly:

[root@ip-XXX-XX-XX-XXX current]# psql --version
psql (PostgreSQL) 9.2.24

compared with running this on a Rails console which shows the RDS version:

irb(main):001:0> ActiveRecord::Base.connection.select_value('SELECT version()')
=> "PostgreSQL 11.13 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 7.3.1 20180712 (Red Hat 7.3.1-12), 64-bit"