Handling environment variables in Elixir?

I figured it out. I put the environment variables within the :prod scope. Working normally now that I moved it outside :prod. Thanks all!

Are you running iex -S mix or just plain iex? Just running iex won’t evaluate any of your project files such as the configuration.

Have you verified that the call in runtime.exs is actually looking for a .env file in the project root (which iex can see) rather than in the config directory?

I will tell you my experience of using it may help.

I create a condition in runtime:

# runtime.exs
if config_env() == :prod do

  amqp_url =
    System.get_env("AMQP_URL") ||
      raise """
          enviroment variable AMQP_URL is missing
      """

  config :pioneer_rpc,
    connection_string: amqp_url

# other config
end

I run the application itself as a system process and specify EnviromentFile=pathToEnvFile in the app.service config

example:

server@server ~> cat /etc/systemd/system/app.service
[Unit]
Description=test
After=network.target

[Service]
Restart=on-failure
EnvironmentFile=/etc/app/env.conf

WorkingDirectory=/opt/app

ExecStart=/opt/app/_build/prod/rel/app/bin/app start
ExecStop=/opt/app/_build/prod/rel/app/bin/app stop

[Install]
WantedBy=multi-user.target

Next, the property can be accessed using Application.get_env(:connection_string).