Environment variable using docker-compose is always null

Questions & Help Questions
,
8

This is my Dockerfile

FROM elixir:1.11-slim
RUN mkdir /app
COPY . /app
WORKDIR /app

# Install hex
RUN mix local.hex --force

#Install rebar
RUN mix local.rebar --force

#Get dependencies
RUN mix deps.get

#Run
RUN mix

This is my docker-compose.yml

version: "3.2"

services:
  checker:
    build:
      context: .
    environment:
      MY_VAR: "hello" 
    restart: on-failure

Mix.exs:

defmodule StockAlert.MixProject do
  use Mix.Project

  def project do
    [
      app: :stock_alert,
      version: "0.1.0",
      elixir: "~> 1.11.0",
      deps: deps()
    ]
  end

  # Configuration for the OTP application.
  #
  # Type `mix help compile.app` for more information.
  def application do
    [
      mod: {StockAlert.Application, []},
      extra_applications: [:elastix,:lager, :logger, :runtime_tools]
    ]
  end

  # Specifies your project dependencies.
  #
  # Type `mix help deps` for examples and options.
  defp deps do
    [
      {:elastix, "~> 0.10.0"},
      {:gettext, "~> 0.11"},
      {:jason, "~> 1.0"},
      {:websockex, "~> 0.4.2"},
      {:poison, "~> 3.1"},
      {:amqp, "~> 2.1"},
      {:json, "~> 1.4"}
    ]
  end
end

StockAlert.Application

defmodule StockAlert.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application
  require Logger

  @registry :workers_registry

  def start(_type, _args) do
    mvar = System.get_env("MY_VAR")
    Logger.info "MY_VAR-> #{mvar}"
  end

  def registry(), do: @registry
end