refactor(config): use secret files in dev mode

- Refactor `config/dev.exs` to use `config/dev.secret.exs` instead of
  fetching the SMTP information from the environment and using hardcoded
  database credentials. This is useful when different developers have
  different database credentials and they use different SMTP adapters
- Add a sample `dev.secret.exs` in `config/dev.secret.sample.exs`. Also
  gitignore the origin `dev.secret.exs` file
- Add instructions on how to setup the config file for development in
  `README.md`
- Add `Plug.Swoosh.MailboxPreview` plug on "/mailbox" route in
  development mode for easier development with e-mails

Signed-off-by: Akshit Garg <garg.akshit@gmail.com>

.gitignore

@@ -36,3 +36,6 @@ npm-debug.log
 .idea
 .env
 .envrc
+
+# Secret config files
+config/*.secret.exs

README.md

@@ -2,6 +2,8 @@
 
 To start your Phoenix server:
 
+  * Copy `config/dev.secret.sample.exs` to `config/dev.secret.exs`
+  * Fill in the SMTP and database configuration in `config/dev.secret.exs`
   * Install dependencies with `mix deps.get`
   * Create and migrate your database with `mix ecto.setup`
   * Install Node.js dependencies with `npm install` inside the `assets` directory

config/dev.exs

@@ -1,14 +1,5 @@
 use Mix.Config
 
-# Configure your database
-config :ketbin, Ketbin.Repo,
-  username: "postgres",
-  password: "postgres",
-  database: "ketbin_dev",
-  hostname: "localhost",
-  show_sensitive_data_on_connection_error: true,
-  pool_size: 10
-
 # For development, we disable any cache and enable
 # debugging and code reloading.
 #
@@ -30,32 +21,6 @@ config :ketbin, KetbinWeb.Endpoint,
     ]
   ]
 
-smtp_relay =
-  System.get_env("SWOOSH_SMTP_RELAY") ||
-    raise """
-    environment variable SWOOSH_SMTP_RELAY is missing.
-    """
-username =
-  System.get_env("SWOOSH_USERNAME") ||
-    raise """
-    environment variable SWOOSH_USERNAME is missing.
-    """
-password =
-  System.get_env("SWOOSH_PASSWORD") ||
-    raise """
-    environment variable SWOOSH_PASSWORD is missing.
-    """
-
-# configure mailer
-config :ketbin, Ketbin.Mailer,
-  adapter: Swoosh.Adapters.SMTP,
-  relay: smtp_relay,
-  username: username,
-  password: password,
-  tls: :always,
-  auth: :always,
-  port: 587
-
 # ## SSL Support
 #
 # In order to use HTTPS in development, a self-signed
@@ -100,3 +65,6 @@ config :phoenix, :stacktrace_depth, 20
 
 # Initialize plugs at runtime for faster development compilation
 config :phoenix, :plug_init_mode, :runtime
+
+# Import the secrets config
+import_config "dev.secret.exs"

config/dev.secret.sample.exs

@@ -0,0 +1,24 @@
+import Mix.Config
+
+# Configure your database
+config :ketbin, Ketbin.Repo,
+  username: "postgres",
+  password: "postgres",
+  database: "ketbin_dev",
+  hostname: "localhost",
+  show_sensitive_data_on_connection_error: true,
+  pool_size: 10
+
+smtp_relay = "<Your SMTP Relay Here>"
+username = "<Your SMTP username here>"
+password = "<Your SMTP password here>"
+
+# configure mailer
+config :ketbin, Ketbin.Mailer,
+  adapter: Swoosh.Adapters.SMTP,
+  relay: smtp_relay,
+  username: username,
+  password: password,
+  tls: :always,
+  auth: :always,
+  port: 587

lib/ketbin_web/router.ex

@@ -59,7 +59,9 @@ defmodule KetbinWeb.Router do
 
     scope "/" do
       pipe_through :browser
+
       live_dashboard "/dashboard", metrics: KetbinWeb.Telemetry
+      forward "/mailbox", Plug.Swoosh.MailboxPreview
     end
   end