PostgreSQL database setup
We at BigBinary use PostgreSQL database on
Heroku.
When our application is deployed to Heroku, it will be running in production
mode.
We can install PostgreSQL by using Homebrew(preferred) or by using
Postgres.app. Go through the next sections to understand how to install and
use PostgreSQL.
Install PostgreSQL using Homebrew
The config/database.yml file should look like this:
The env variables in the config will be populated during runtime. If you prefer
to hardcode the values for PG_USER etc, then you can do that. The
config/database.yml should be ignored via .gitignore. It should never be
committed to your Git tree.
After installing PostgreSQL, you can check the version you are running by
executing:
Once the installation is complete we need to start PostgreSQL service to use
postgresql in our project:
You can check if the PostgreSQL is working properly and accepting responses by
running the following command:
This should return an output similar to:
Sometimes the above mentioned postgres installation method leads to a
Library not loaded error like this:
The issue is that even after using command the brew install postgres, brew
might install a specific version like version 14. Then all the postgres
related libraries will be tracked under a directory named as postgres@14. But
when the pg gem is installed without passing in any config, it will always
look for the folder named as postgres without any versioning. And this
difference in folder name results in the Library not loaded error.
To fix this issue reinstall the postgres with the version, like this:
This will inform the pg gem to look for postgres@14 directory and the
postgres library will be loaded successfully.
Handle services using brew
In macOS, services are the files ending with the .plist file extension. Let's
see what all services your mac has. Go to ~/Library/LaunchAgents or
/Library/LaunchAgents and look for the files ending with .plist. All those
.plist files are the services installed on your mac.
launchctl is a tool used for managing services in macOS. launchctl loads and
unloads services that will start automatically at login.
We can load the services at the time of login with launchctl like this:
We can also unload the services, like this:
So to run a service we need the .plist file location and the launchctl
commands to run it. But it's not possible to remember .plist file location.
Also, launchctl commands are complex and hard to remember. We can deal with
services without the knowledge of .plist file locations and the launchctl
commands using Homebrew. Homebrew provides an interface to handle services with
ease.
We can start a postgresql service with Homebrew, like this:
The above mentioned command runs the postgresql's .plist file using the
launchctl.
If the system has multiple versions of postgresql, then we will have to
specify the version like this:
We can check all the versions installed for postgresql, like this:
We can restart the service, like this:
We can check all the currently loaded services like this:
For more Homebrew commands refer
this cheat sheet from devhints.io.
Install PostgreSQL using Postgres app
If you are using a macOS and if you are not able to setup PostgreSQL via
Homebrew as mentioned in the above section, then
Postgres.app is another option.
The config/database.yml file for the Postgres.app should be like this:
Please note that the config/database.yml file to be added after brew install
will be defined in the upcoming chapters and it is different from the one
defined for the Postgres.app installation.
Given that currently, we are using PostgreSQL only in the production
environment, we don't need to make any modifications to the
config/database.yml file. The config/database.yml file is anyways ignored by
Git. The use case of that file is only in local environments. We will learn more
about the same in the upcoming chapters.
Update Gemfile to use PostgreSQL
Installing and configuring "PostgreSQL" on a personal laptop can be tricky. So
here is what we are going to do.
We will use the sqlite3 gem for both the development and test
environments.
We will use the pg gem only in the production environment. In this way, we
do not have to install PostgreSQL on our laptop.
Modify Gemfile to use sqlite3 only in the development and test environment.
Note that in the following code, we have added group. It allows us to specify
the environment in which we want to use a particular gem:
Now let's add the pg gem for production:
The => representation is called the hash-rocket representation and this is an
older way of writing the newer JSON-style representation, which is
group: [:production].
Install the gems:
