Install postgresql gem `pg` on macOS

install_pg_gem.md

Installing pg gem on macOS

If you're trying to install the postgresql gem pg and it is failing with the following error message:

Installing pg 1.2.3 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: ~/.rbenv/versions/3.0.0/lib/ruby/gems/3.0.0/gems/pg-1.2.3/ext
~/.rbenv/versions/3.0.0/bin/ruby -I ~/.rbenv/versions/3.0.0/lib/ruby/3.0.0 -r ./siteconf20210125-97201-pycpo.rb 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

The following helped me resolve the issue without having to install the entire postgresql as recommended in the stop Stack Overflow post (already using it in a Docker container):

1. brew install libpq
2. gem install pg -- --with-pg-config=/usr/local/opt/libpq/bin/pg_config

For intel mac:

brew install libpq
bundle config build.pg -- --with-pg-config=/usr/local/opt/libpq/bin/pg_config

Yo pg_config should be on your machine after a brew install postgresql so no need to do libpq or gem install dances

sudo find / -name "pg_config" -print
bundle config set build.pg --with-pg-config=/path/to/pg_config

Also symlink is not ideal but will work

In case anyone else had this problem, I saw the following error when I tried to install with the flag as mentioned here:

gem install pg -v '1.1.0' --source 'https://rubygems.org/' --with-pg-config=/usr/local/opt/libpq/bin/pg_config
ERROR:  While executing gem ... (OptionParser::InvalidOption)
    invalid option: --with-pg-config=/usr/local/opt/libpq/bin/pg_config

But, changing the bundle config as some have mentioned:

bundle config build.pg --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config

worked like a charm on my Apple Silicon machine.

I'm on Mac OS 12.6, and trying to locate pg_config. Running

sudo find / -name "pg_config" -print

resulted in a bunch of results like:

/usr/local/Cellar/libpq/14.5/bin/pg_config
/Library/PostgreSQL/14/debug_symbols/bin/pg_config.dSYM/Contents/Resources/DWARF/pg_config
/Library/PostgreSQL/14/bin/pg_config

I have Postgres installed with the installer package from their website, and not with brew install postgresql. So what's the path I need for installing the pg gem?

Btw, when I installed libpq I had the following message:

libpq is keg-only, which means it was not symlinked into /usr/local,
because conflicts with postgres formula.

If you need to have libpq first in your PATH, run:
  echo 'export PATH="/usr/local/opt/libpq/bin:$PATH"' >> /Users/me/.bash_profile

@fullstackplus uninstall libpq and then use the Cellar pg_config in the bundle config setting. You are seeing multiple because you have multiple versions of Postgres installed. The Library one is likely a system version or a version that maybe an App installed installed whereas the Cellar version is the homebrew version. You also need to make sure the Cellar version is in your PATH.

@darrenterhune Thanks, weird that I have multiple versions of Postgres — I only installed it once. Would you recommend also uninstalling all Postgres versions except the Homebrew one?

Also, I just ran brew list and there's no Postgres formula! Only libpq.

@fullstackplus I would definitely try and figure out how they go there and uninstall them. I have not used apps to install postgres before. It could be something like postgres.app or pg_admin installer, I'm not sure. I don't think any versions of mac os x come preloaded with postgres on them but 🤷‍♂️

If no versions of postgres from homebrew just uninstall libpq and then install it with homebrew.

@darrenterhune Thanks man. I don't think Postgres came pre-installed with my Mac, running which postgres andwhich postgresql yields nothing, while running which sqlite3 yields:

/usr/bin/sqlite3

So I must have installed it indirectly somehow.

bundle config build.pg --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config fixed it for my MBP M1.

brew install libpq
bundle config build.pg --with-pg-config="$(brew --prefix)/opt/libpq/bin/pg_config"

You should not assume the brew installation path :)

bundle config build.pg --with-pg-config="$(brew --prefix)/opt/libpq/bin/pg_config"

Works wonder ! One of the the cleanest answers so far !

You can also use "${HOMEBREW_PREFIX}/opt/libpq/bin/pg_config" to avoid creating a new brew process.

bundle config build.pg --with-pg-config="$(brew --prefix)/opt/libpq/bin/pg_config"

Amazing, many other solutions didn't work (from fresh Ventura OS install).

On Apple Silicon, after installing the libpq, running gem install pg -- --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config

should do the trick.

@isheebo you just saved me 10000 hours I owe you everything

What worked for me was the suggestion by @oamado:

gem install pg -v '0.18.4' -- --with-cflags="-Wno-error=implicit-function-declaration"

I am on an older Mac (MacBook Pro 2018) running macOS 12.5.1 (Monterey).

To use with bundler / apple silicon:

brew install libpq
bundle config build.pg --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config
bundle

This worked for m1, Postgres.app. Thank you
But after that, psql may not work. The following helped me:
brew link --force libpq

gem install pg -- --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config

Works for me. Thanks!

To use with bundler / apple silicon:

brew install libpq
bundle config build.pg --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config
bundle

Thanks! It works!

To use with bundler / apple silicon:

brew install libpq
bundle config build.pg --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config
bundle

Worked for me. I'm using Apple M1 Sonoma.

gem install pg -- --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config

You may need to do a user-level install depending on permissions.

 gem install pg --user-install -- --with-pg-config=/opt/homebrew/opt/libpq/bin/pg_config

works for me.

Switching the ruby version worked for me
rbenv global 3.2.2
sudo chown -R $(whoami) ~/.rbenv
gem install pg

Merci!!