Installing Postgres on Digital Ocean Droplet for a Phoenix Application

Andrew Barr, Tuesday, 17 November 2020

Installing Postgres

This post assumes you have a Digital Ocean Droplet using Ubuntu and setup for an Elixir Application using Phoenix. To get started open a ssh session to your Droplet and run the following commands. If you have not setup your server check out this Post.

$ sudo apt update
$ sudo apt install postgresql postgresql-contrib

By default the installation process will setup a user called postgres so you can test the installion by changing user accounts and opening the Postgres prompt:

$ sudo -i -u postgres
$ psql

If your installation is successful you should now be able to list all of the databases:

postgres=# \l

Once you are sure everything is working type \q to exit the prompt and then exit to go back to your user account. Back in your own account we now want to create a user that can connect to our applicatiosn database:

$ sudo -u postgres createuser --interactive

It will prompt you for a user name and role. At this stage select yes for superuser. You can create different roles later and modify the account as required. Postgres requires that each user has a database of the same name so at the cmd line type:

$ sudo -u postgres createdb user-name-you-chose

No create a local user so that you can use the ident based authentication used by Ubuntu:

$ sudo adduser user-name-you-chose

Now you can open a Postgres prompt using your new user:

$ sudo -u user-name-you-chose psql

Test the account by listing the databases, then create a database for you Phoenix application:

user-name-you-chose=# \l
user-name-you-chose=# createdb application_name_prod;
user-name-you-chose=# \q

Back at the prompt set a password for user-name-you-chose so the application can connect securely:

$ sudo -u postgres psql
postgres=# \password user-name-you-chose 
# Follow prompts to set password
postgres=# \q

Modify Phoenix Aplication

I am using Github Actions to deploy my Phoenix application and added a Secret to the Github repo called PG_PASS. Alternatively you may wish to use prod_secrets.exs on the Droplet. If you are using ENV_VARS modify your prod.exs to include:

config :my_app, MyApp.Repo,
  username: "user-name-you-chose",
  database: "my_app_prod",
  # prod_secrets.exs - password here
  password: System.get_env("PG_PASS"), 
  hostname: "127.0.0.1",
  pool_size: 10

You can now create a PROD release and test your database connection. I will write a post shortly to show how I am using Github Actions to deploy my applications.