How to run rails applications on digitalocean using "rails s"

You can indeed run multiple Rails applications on a single server. However, you will need to configure Nginx and Unicorn (or Passenger, Puma, etc.) for each Rails application you want to serve.

It is not recommended to switch apps by manually starting/stopping services or running “rails s” for production. This command starts a server intended for development, which is not suitable for handling real-world traffic.

Here’s a simplified process to set up a new Rails app alongside your existing one:

1. Create a new Rails app:

Create your new Rails app in a new directory:

cd ~
rails new my_second_app

2. Set up a new Unicorn configuration:

You should create a separate Unicorn configuration file for your new app. The file might be located at ~/my_second_app/config/unicorn.rb, and it should be different from your existing Unicorn configuration to avoid conflicts.

3. Set up a new Nginx server block:

Create a new Nginx configuration file for your new app. This will likely be a new file in the /etc/nginx/sites-available/ directory. The server block should have a different server_name from your existing configuration, and it should proxy requests to the Unicorn socket for your new app.

4. Link the Nginx server block:

Create a symbolic link to the new Nginx configuration file in the sites-enabled directory:

sudo ln -s /etc/nginx/sites-available/my_second_app /etc/nginx/sites-enabled/

5. Restart Unicorn and Nginx:

Finally, you need to restart Unicorn and Nginx for your changes to take effect. How you do this depends on how you have set up your server. It might look something like this:

sudo service unicorn_my_second_app restart
sudo service nginx restart

This setup allows you to run both apps simultaneously, each with its own domain name. Note that if you are using the same droplet, you will need to point a new domain name to your droplet’s IP address for the new Rails application. This new domain should match the server_name in your Nginx server block for the new app.