Question

Elixir, Ecto / Phoenix + Managed Postgres Db

I’m trying to setup an Elixir / Phoenix / Ecto project on my droplet and connect to a DO managed postgresql. No matter what I do I can’t connect to my DB properly:

** (Postgrex.Error) FATAL 3D000 (invalid_catalog_name) database “postgres” does not exist (db_connection) lib/db_connection/connection.ex:84: DBConnection.Connection.connect/2 (connection) lib/connection.ex:622: Connection.enter_connect/5 (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3

My connection string is right, connectivity seems fine ( I setup my droplet to be able to access the db cluster) but Elixir/Ecto complains with the above error.

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Brian Hogan • March 13, 2019
Accepted Answer

HI! Sorry to hear you ran into a snag. I just set up a brand new Elixir/Phoenix app myself and ran into the exact same issue you had.

I did a little digging and it seems that either Ecto or Postgres expects the postgres database to exist.

I logged into the db directly with my doadmin user and looked around, and surely enough there’s no postgres database. So I created one:

CREATE DATABASE postgres WITH OWNER doadmin

Then I disconnected from the console, re-ran mix ecto.create and was greeted with:

The database for Hello.Repo has been created

I hope that helps move you forward!

stanislavgenchev • December 29, 2020

Ecto uses the ‘maintenance_database’ property to set the name of the database to connect to when creating or dropping the database. By default it’s “postgres”. In DigitalOcean, when a cluster is created, the default database is called “defaultdb”. So all you need to do is add the following config:

# Configure your database
config :elixir_app, ElixirApp.Repo,
  ...
  database: "elixir_app_dev",
  maintenance_database: "defaultdb",
  ...

Here is the documentation: https://hexdocs.pm/ecto_sql/Ecto.Adapters.Postgres.html