Get the current database connection information with Ecto and Phoenix

How does one get the database name of the current connection / Ecto Repo that you're using in your Phoenix app? Well, the way you do it is to look at how the credentials are configured.

In Phoenix, we use the config command which comes from Config. In turn, MyApp.Repo that you invoke with use Ecto.Repo reads that configuration.

For our purposes, we'll use Application.fetch_env from the Config package to retrieve the value for that Repo:

iex(mm-36@rem-a-mcamp)1> Application.get_env(:my_app, MyApp.Repo)
[
  adapter: Ecto.Adapters.Postgres,
  migration_primary_key: [id: :uuid, type: :binary_id],
  migration_timestamps: [type: :utc_datetime_usec],
  telemetry_prefix: [:my_app, :repo],
  show_sensitive_data_on_connection_error: true,
  database: "myapp",
  hostname: "localhost",
  password: "",
  pool_size: 10,
  port: 5432,
  timeout: 10000,
  username: "postgres",
  min_results_estimated_count: 50000
]

As you can see, we can get information like the database name etc.

How is that set in the first place, you may ask? We may configure it initially within a config/*.exs file:

config :my_app, MyApp.Repo,
  adapter: Ecto.Adapters.Postgres,
  migration_primary_key: [id: :uuid, type: :binary_id],
  migration_timestamps: [type: :utc_datetime_usec],
  telemetry_prefix: [:my_app, :repo]

config :my_app, MyApp.Repo,
  hostname: System.get_env("POSTGRES_HOSTNAME", "localhost"),
  password: System.get_env("POSTGRES_PASSWORD", "password"),
  pool_size: String.to_integer(System.get_env("POSTGRES_POOL_SIZE", "50")),
  port: String.to_integer(System.get_env("POSTGRES_PORT", "5432")),
  timeout: String.to_integer(System.get_env("POSTGRES_QUERY_TIMEOUT", "10000")),
  username: System.get_env("POSTGRES_USERNAME", "postgres"),

Two computers and a microphone

Get the current database connection information with Ecto and Phoenix