### Install dependencies

Source: https://dotenvy.hexdocs.pm/getting_started.html

Navigate to the project directory and fetch dependencies.

```bash
cd example
mix deps.get
```

--------------------------------

### Define database variables in envs/dev.env

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Example configuration for development database settings.

```text
PG_USERNAME=postgres
PG_PASSWORD=postgres
PG_HOSTNAME=localhost
PG_PORT=5432
PG_DATABASE=m_app_dev
PG_POOL_SIZE=10
PG_POOL=DBConnection.ConnectionPool
PG_SSL=true
```

--------------------------------

### Install local application in Livebook

Source: https://dotenvy.hexdocs.pm/livebooks.html

Configure Mix.install to include a local application that utilizes Dotenvy.

```elixir
Mix.install(
  [
    {:app_using_dotenvy, path: "/path/to/app_using_dotenvy", env: :dev}
  ],
  config_path: :app_using_dotenvy,
  lockfile: :app_using_dotenvy
)
```

--------------------------------

### Define database variables in envs/test.env

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Example configuration for test database settings.

```text
PG_USERNAME=postgres
PG_PASSWORD=postgres
PG_HOSTNAME=localhost
PG_PORT=5432
PG_DATABASE=my_app_test
PG_POOL_SIZE=10
PG_POOL=Ecto.Adapters.SQL.Sandbox
PG_SSL=false
```

--------------------------------

### Define environment variables in .env file

Source: https://dotenvy.hexdocs.pm/

Example content for a .env file used to store configuration defaults.

```text
# .env
DATABASE=myapp_dev
USERNAME=myuser
PASSWORD=mypassword
HOSTNAME=localhost
POOL_SIZE=10
POOL=
```

--------------------------------

### Reference system variables in .env

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Example of a .env file using variable substitution with system environment variables.

```text
  # .env
  CACHE_DIR=${HOME}/cache
```

--------------------------------

### Example variable names

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Examples of valid and invalid variable naming conventions.

```text
DATABASE_URL  # ok  
foobar        # ok  
NO-WORK       # <-- invalid !!!
ÜBER          # <-- invalid !!!
2MUCH         # <-- invalid !!!
```

--------------------------------

### Examples of to!/2 usage

Source: https://dotenvy.hexdocs.pm/Dotenvy.Transformer.html

Demonstrates various type conversions including booleans, integers, modules, and custom transformation functions.

```elixir
iex> to!("debug", :atom)
:debug
iex> to!("", :boolean)
false
iex> to!("", :boolean?)
nil
iex> to!("5432", :integer)
5432
iex> to!("DateTime", :module)
DateTime
iex> to!("foo", fn val -> val <> "bar" end)
"foobar"
iex> Dotenvy.Transformer.to!("Oops", :float)
  ** (Dotenvy.Error) Unparsable as float
  (dotenvy 1.0.0) lib/dotenvy/transformer.ex:165: Dotenvy.Transformer.to!/2
```

--------------------------------

### Configure Swoosh Mailer Adapter

Source: https://dotenvy.hexdocs.pm/phoenix.html

Example configuration for setting a production mailer adapter and its required API client.

```elixir
config :your_app, YourApp.Mailer,
  adapter: Swoosh.Adapters.Mailgun,
  api_key: System.get_env("MAILGUN_API_KEY"),
  domain: System.get_env("MAILGUN_DOMAIN")
```

```elixir
config :swoosh, :api_client, Swoosh.ApiClient.Hackney
```

--------------------------------

### Integrating Legacy Secrets in runtime.exs

Source: https://dotenvy.hexdocs.pm/1password.html

Example configuration for loading external shell-sourced environment variables into Dotenvy.

```elixir
# config/runtime.exs
import Config
import Dotenvy

env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

{raw_envs, _} = System.shell(~s'bash -c "source #{Path.absname("secrets.sh", env_dir_prefix)} && env"')
{:ok, system_env_vars} = Dotenvy.Parser.parse(raw_envs)

source!([
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    system_env_vars
  ])
```

--------------------------------

### Install Dotenvy Generators

Source: https://dotenvy.hexdocs.pm/generators.html

Commands to remove existing Phoenix generators and install the Dotenvy generator scripts.

```bash
mix archive.uninstall phx_new
mix archive.install hex dotenvy_generators
```

--------------------------------

### Example error output

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

The format of the error message when a custom validation fails.

```text
** (RuntimeError) Error converting variable SOME_BOOL using custom function: strict_boolean! values must be either true or false
```

--------------------------------

### Defining a configuration contract

Source: https://dotenvy.hexdocs.pm/getting_started.html

Uses env! to mandate that a specific environment variable must be present for the application to start.

```elixir
config :example, :password, env!("PASSWORD", :string!)
```

--------------------------------

### Providing environment variables via command line

Source: https://dotenvy.hexdocs.pm/getting_started.html

Passing a required variable directly to the application startup command.

```bash
PASSWORD=xxxx iex -S mix
```

--------------------------------

### Configure runtime settings in runtime.exs

Source: https://dotenvy.hexdocs.pm/minimal.html

Use runtime.exs to load environment variables dynamically at startup, ensuring sensitive or environment-specific data is injected correctly.

```elixir
import Config
import Dotenvy

env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!([
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ])


config :myapp, MyApp.Repo,
  database: env!("DATABASE", :string!),
  username: env!("USERNAME", :string),
  password: env!("PASSWORD", :string),
  hostname: env!("HOSTNAME", :string!),
  pool_size: env!("POOL_SIZE", :integer),
  adapter: env("ADAPTER", :module, Ecto.Adapters.Postgres),
  pool: env!("POOL", :module?)

  # etc...
```

--------------------------------

### Reference system variables before and after

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Sourcing system variables both before and after .env files to handle substitution and final precedence.

```elixir
  iex> Dotenvy.source([System.get_env(), ".env", System.get_env()])
```

--------------------------------

### Define basic key-value pairs

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Standard format for storing environment variables in a .env file.

```text
S3_BUCKET=YOURS3BUCKET
SECRET_KEY=YOURSECRETKEYGOESHERE
```

--------------------------------

### Use export prefix

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Optional prefix to allow sourcing the file directly in Bash.

```bash
export S3_BUCKET=YOURS3BUCKET
export SECRET_KEY=YOURSECRETKEYGOESHERE
```

--------------------------------

### Configure Development Environment Variables

Source: https://dotenvy.hexdocs.pm/phoenix.html

Defines local development settings including database connection strings and server ports.

```text
# envs/.dev.env
HTTP_INTERFACE=127.0.0.1
HTTP_CHECK_ORIGIN=false
PORT=4000
SECRET_KEY_BASE=6D1kPrXseBg9F1O9cZUd8ocIH7l3OgT9ZlopIXqDr+jYjNrcvbjqwNvzHPKIakcF
PHX_URL_PORT=${PORT}
PHX_PLUGIN_INIT_MODE=runtime

PG_USERNAME=postgres
PG_PASSWORD=postgres
PG_HOSTNAME=localhost
PG_DATABASE=your_app_dev
PG_POOL=DBConnection.ConnectionPool
POOL_SIZE=10
# DATABASE_URL format is `ecto://USER:PASS@HOST/DATABASE`
DATABASE_URL=ecto://${PG_USERNAME}:${PG_PASSWORD}@${PG_HOSTNAME}/${PG_DATABASE}
SHOW_SENSITIVE_DATA_ON_CONNECTION_ERROR=true
ECTO_IPV6=false
ECTO_STACKTRACE=true
```

--------------------------------

### Configure database runtime settings

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Use env! to map environment variables to database configuration keys.

```elixir
import Config
import Dotenvy

env_dir = System.get_env("RELEASE_ROOT") || Path.expand("./envs")
  
source!([
    Path.absname(".env", dir),
    Path.absname(".#{config_env()}.env", env_dir),
    Path.absname(".#{config_env()}.overrides.env", env_dir),
    System.get_env()
  ])

config :my_app, MyApp.PGRepo,
  pool: env!("PG_POOL", :module?),
  pool_size: env!("PG_POOL_SIZE", :integer),
  database: env!("PG_DATABASE", :string),
  username: env!("PG_USERNAME", :string),
  password: env!("PG_PASSWORD", :string),
  port: env!("PG_PORT", :integer),
  hostname: env!("PG_HOSTNAME", :string)
```

--------------------------------

### Configure Production Environment Variables

Source: https://dotenvy.hexdocs.pm/phoenix.html

Defines production settings, including host-specific configurations and security-hardened defaults.

```text
# envs/.prod.env
ENABLE_DISTRIBUTED_MODE=true
# DNS_CLUSTER_QUERY= # set by Fly.io

HTTP_INTERFACE=0:0:0:0:0:0:0:0
HTTP_CHECK_ORIGIN=true
# PORT= # set by Fly.io
# SECRET_KEY_BASE= # Set by Fly.io
PHX_SERVER=true
PHX_HOST=your-app-website.com
PHX_URL_PORT=443
PHX_URL_SCHEME=https
PHX_CACHE_STATIC_MANIFEST=priv/static/cache_manifest.json
PHX_STACKTRACE_DEPTH=false
PHX_PLUGIN_INIT_MODE=compile

# DATABASE_URL= # set by Fly.io
SHOW_SENSITIVE_DATA_ON_CONNECTION_ERROR=false
ECTO_IPV6=true
ECTO_STACKTRACE=false

SWOOSH_API_CLIENT=Swoosh.ApiClient.Finch
SWOOSH_LOCAL_MEMORY_STORAGE=false
# For production it's recommended to configure a different adapter...
# SWOOSH_MAILER_ADAPTER=Swoosh.Adapters.Local
```

--------------------------------

### source!(files, opts)

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Loads environment variables from the specified files. This function returns a map of the loaded variables on success or raises an error if the operation fails.

```APIDOC
## source!(files, opts)

### Description
Loads environment variables from one or more files. Returns a map of the environment variables on success or raises an exception on failure.

### Signature
`source!(files :: binary() | [binary()], opts :: keyword()) :: %{optional(String.t()) => String.t()} | no_return()`

### Parameters
- **files** (binary() | [binary()]) - Required - A single file path or a list of file paths to load.
- **opts** (keyword()) - Required - Configuration options for the loading process.
```

--------------------------------

### Generate a new Dotenvy application

Source: https://dotenvy.hexdocs.pm/getting_started.html

Use the mix task to scaffold a new project with Dotenvy support.

```bash
mix dot.new example
```

--------------------------------

### Configure release overlays in mix.exs

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Include the envs directory in the application release.

```elixir
defp releases do
[
    my_app: [
      overlays: ["envs/"]
    ]
]
end
```

--------------------------------

### Environment Variable Configuration File

Source: https://dotenvy.hexdocs.pm/phoenix.html

Default configuration values for Phoenix, database, and mailer settings stored in a .env file.

```bash
# envs/.env (default/shared config)
# ###################
# Distributed Node  #
# ###################
# If distributed mode is enabled, the DNS_CLUSTER_QUERY variable must have a value
ENABLE_DISTRIBUTED_MODE=false
DNS_CLUSTER_QUERY=

# #####################
# Phoenix / Webserver #
# #####################
# The interface(s) to listen on.
# Can be specified as the following formats:
# `1.2.3.4` for IPv4 addresses (using period separators)
# `1:2:3:4:5:6:7:8` for IPv6 addresses (using colon separators)
# 
# To bind to loopback IPv4 address & prevent access from other machines: `127.0.0.1`
# To allow access from other machines: `0.0.0.0`
# 
# To enable IPv6 and bind on all interfaces: `0:0:0:0:0:0:0:0`
# For local network only access: `0:0:0:0:0:0:0:1`
# 
# See the documentation on https://hexdocs.pm/bandit/Bandit.html#t:options/0
# for details about using IPv6 vs IPv4 and loopback vs public addresses.
HTTP_INTERFACE=127.0.0.1
HTTP_CHECK_ORIGIN=false
# Port where HTTP requests will be accepted
PORT=4000
# A secret key used as a base to generate secrets for encrypting and signing data. 
# For example, cookies and tokens are signed by default, but they may also be 
# encrypted if desired. Must be set per application.
SECRET_KEY_BASE=
# Boolean indicating whether to start the Phoenix webserver implicitly.
# Usually this is false for dev and true for prod
PHX_SERVER=false
# PHX_HOST, PHX_URL_PORT, and PHX_URL_SCHEME are used to create links
PHX_HOST=localhost
# Duplicate the ${PORT} value for http; 443 recommended for https
PHX_URL_PORT=
# scheme may be either http or https
PHX_URL_SCHEME=http
# Specifies the path to a cache manifes containing the digested version of 
# static files. This manifest is generated by the `mix assets.deploy` task,
# which you should run after static files are built and
# before starting your production server.
# Leave empty for dev or when you do not need a manifest
PHX_CACHE_STATIC_MANIFEST=
# Set a higher stacktrace during development, e.g. 20, or set to false to disable.
# Disabling is recommended in prod as building large stacktraces may be expensive.
PHX_STACKTRACE_DEPTH=20
# Initialize plugs at runtime for faster development compilation
# values can be :runtime or :compile; must be :compile in prod (the default)
PHX_PLUGIN_INIT_MODE=compile

############
# Database #
############
# The MIX_TEST_PARTITION environment variable can be used
# to provide built-in test partitioning in CI environment.
# Run `mix help test` for more information.
MIX_TEST_PARTITION=
PG_USERNAME=postgres
PG_PASSWORD=postgres
PG_HOSTNAME=localhost
PG_DATABASE=your_app_dev
PG_POOL=DBConnection.ConnectionPool
POOL_SIZE=10
# DATABASE_URL format is `ecto://USER:PASS@HOST/DATABASE`
DATABASE_URL=ecto://${PG_USERNAME}:${PG_PASSWORD}@${PG_HOSTNAME}/${PG_DATABASE}
SHOW_SENSITIVE_DATA_ON_CONNECTION_ERROR=true
ECTO_IPV6=false
ECTO_STACKTRACE=true

###################
# Swoosh / Mailer #
###################
# Specify a module as a Swoosh API client for production adapters or set to false
# to disable. See https://hexdocs.pm/swoosh/Swoosh.ApiClient.html
SWOOSH_API_CLIENT=false
SWOOSH_LOCAL_MEMORY_STORAGE=true
# By default it uses the Swoosh.Adapters.Local adapter which stores the emails
# locally. You can see the emails in your browser, at "/dev/mailbox".
# For production it's recommended to configure a different adapter
SWOOSH_MAILER_ADAPTER=Swoosh.Adapters.Local
```

--------------------------------

### Source multiple files with system precedence

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

A common pattern for sourcing environment-specific files and overriding them with system environment variables.

```elixir
  iex> Dotenvy.source([
    "#{config_env()}.env",
    "#{config_env()}.override.env",
    System.get_env()
  ])
```

--------------------------------

### Customize Environment Directory

Source: https://dotenvy.hexdocs.pm/releases.html

Update both runtime.exs and mix.exs when using a custom directory name for .env files instead of the default.

```elixir
# config/runtime.exs
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./xyz")
# ... etc...
```

```elixir
# mix.exs
  defp releases do
    [
      my_app: [
        overlays: ["xyz/"]
      ]
    ]
  end
```

--------------------------------

### Configure Runtime Environment Loading

Source: https://dotenvy.hexdocs.pm/releases.html

Load environment variables from .env files in the specified directory within config/runtime.exs, ensuring absolute paths are used.

```elixir
import Config
import Dotenvy

# For local development, read dotenv files inside the envs/ dir;
# for releases, read them at the RELEASE_ROOT
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!([
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ])
```

```elixir
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!([
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ])
```

--------------------------------

### Include system variables for substitution

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Passing system environment variables as the first input to enable substitution within .env files.

```elixir
  iex> Dotenvy.source([System.get_env(), ".env"])
```

--------------------------------

### Configure compile-time settings in config.exs

Source: https://dotenvy.hexdocs.pm/minimal.html

Use environment-specific blocks within config.exs to handle compile-time configuration without separate environment files.

```elixir
# compile-time config
import Config

# Dev
if config_env() == :dev do
    config :logger, :console, 
        level: :debug,
        format: "[$level] $message\n"
end

# Test
if config_env() == :test do
    config :logger, :console, 
            level: :warning,
            format: "[$level] $message\n"
end

# Prod
if config_env() == :prod do
    config :logger, :console,
        format: "$time $metadata[$level] $message\n",
        level: :info,
        metadata: [:request_id]
end
```

--------------------------------

### source!(files, opts \ [])

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Similar to source/2, but returns the accumulated map on success or raises an error on failure.

```APIDOC
## source!(files, opts \ [])

### Description
As source/2, but returns a map on success or raises on error.

### Parameters
- **files** (input_source) - Required - A path to an env file or a map of key-value pairs.
- **opts** (Keyword) - Optional - Configuration options for the source operation.
```

--------------------------------

### Dynamic Swoosh and Mailer Configuration

Source: https://dotenvy.hexdocs.pm/phoenix.html

Configuration logic using environment variables to determine the API client and mailer adapter at runtime.

```elixir
if env!("SWOOSH_API_CLIENT", :boolean) do
  config :swoosh, api_client: env!("SWOOSH_API_CLIENT", :module!), finch_name: YourApp.Finch
else
  config :swoosh, api_client: false
end

config :your_app, YourApp.Mailer, adapter: env!("SWOOSH_MAILER_ADAPTER", :module)
config :swoosh, api_client: Swoosh.ApiClient.Finch, finch_name: YourApp.Finch
config :swoosh, local: env!("SWOOSH_LOCAL_MEMORY_STORAGE", :boolean)
```

--------------------------------

### Parse a single file

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

The simplest implementation of source/2 to parse a single .env file.

```elixir
iex> Dotenvy.source(".env")
{:ok, %{
  "TIMEOUT" => "5000",
  "DATABASE_URL" => "postgres://postgres:postgres@localhost/myapp",
  # ...etc...
  }
}
```

--------------------------------

### Configure Test Environment Variables

Source: https://dotenvy.hexdocs.pm/phoenix.html

Defines test-specific settings, utilizing the Ecto SQL Sandbox for database operations.

```text
# envs/.test.env
HTTP_INTERFACE=127.0.0.1
HTTP_CHECK_ORIGIN=false
PORT=4002
SECRET_KEY_BASE=514niO7SLGRKi01EN1fQUqekoyfHSQL0640m64tAkJSPG7anLA6iPxWrcIUzCgyA
PHX_URL_PORT=${PORT}
PHX_PLUGIN_INIT_MODE=runtime

PG_USERNAME=postgres
PG_PASSWORD=postgres
PG_HOSTNAME=localhost
PG_DATABASE=your_app_test
PG_POOL=Ecto.Adapters.SQL.Sandbox
POOL_SIZE=10
# DATABASE_URL format is `ecto://USER:PASS@HOST/DATABASE`
DATABASE_URL=ecto://${PG_USERNAME}:${PG_PASSWORD}@${PG_HOSTNAME}/${PG_DATABASE}
SHOW_SENSITIVE_DATA_ON_CONNECTION_ERROR=true
ECTO_IPV6=false
ECTO_STACKTRACE=true

SWOOSH_MAILER_ADAPTER=Swoosh.Adapters.Test
```

--------------------------------

### Configure Dotenvy with Absolute Paths

Source: https://dotenvy.hexdocs.pm/flyio.html

Use Path.absname/2 to ensure environment files are correctly located regardless of the RELEASE_ROOT value.

```elixir
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!(
  [
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ],
  require_files: [Path.absname(".env", env_dir_prefix)]
)
```

--------------------------------

### Configure config/config.exs for Phoenix

Source: https://dotenvy.hexdocs.pm/phoenix.html

Defines general application settings, endpoint configuration, and asset build tools. Ensure placeholders like YourApp are replaced with your actual application module names.

```elixir
# config/config.exs
# This file is responsible for configuring your application
# and its dependencies with the aid of the Config module.
#
# This configuration file is loaded before any dependency and
# is restricted to this project.

# General application configuration
import Config

config :your_app,
  ecto_repos: [YourApp.Repo],
  generators: [timestamp_type: :utc_datetime]

# Configures the endpoint
config :your_app, YourAppWeb.Endpoint,
  adapter: Bandit.PhoenixAdapter,
  render_errors: [
    formats: [html: YourAppWeb.ErrorHTML, json: YourAppWeb.ErrorJSON],
    layout: false
  ],
  pubsub_server: YourApp.PubSub,
  live_view: [signing_salt: "xyz123AB"]

# Configure esbuild (the version is required)
config :esbuild,
  version: "0.17.11",
  your_app: [
    args:
      ~w(js/app.js --bundle --target=es2017 --outdir=../priv/static/assets --external:/fonts/* --external:/images/*),
    cd: Path.expand("../assets", __DIR__),
    env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
  ]

# Configure tailwind (the version is required)
config :tailwind,
  version: "3.4.3",
  your_app: [
    args: ~w(
      --config=tailwind.config.js
      --input=css/app.css
      --output=../priv/static/assets/app.css
    ),
    cd: Path.expand("../assets", __DIR__)
  ]

# Configures Elixir's Logger (compile-time config)
config :logger, :console,
  format: "$time $metadata[$level] $message\n",
  metadata: [:request_id]

# Import environment specific config. This must remain at the bottom
# of this file so it overrides the configuration defined above.
import_config "#{config_env()}.exs"
```

--------------------------------

### Configure Phoenix Runtime with Dotenvy

Source: https://dotenvy.hexdocs.pm/phoenix.html

Uses Dotenvy to load environment variables at runtime for database, endpoint, and server settings.

```elixir
# config/runtime.exs
import Config
import Dotenvy

# For local development, read dotenv files inside the envs/ dir;
# for releases, read them at the RELEASE_ROOT
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!(
  [
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ],
  require_files: [Path.absname(".env", env_dir_prefix)]
)


# config/runtime.exs is executed for all environments, including
# during releases. It is executed after compilation and before the
# system starts. Do not define any compile-time configuration in here,
# as it won't be applied.

# ## Using releases
#
# If you use `mix release`, you need to explicitly enable the server
# by passing the PHX_SERVER=true when you start it:
#
#     PHX_SERVER=true bin/your_app start
#
# Alternatively, you can use `mix phx.gen.release` to generate a `bin/server`
# script that automatically sets the env var above.
if env!("PHX_SERVER", :boolean!) do
  config :your_app, YourAppWeb.Endpoint, server: true
end

# Initialize plugs at runtime for faster development compilation
# values can be :runtime or :compile; must be :compile in prod (the default)
config :phoenix, :plug_init_mode, env!("PHX_PLUGIN_INIT_MODE", :existing_atom!)

# Use Jason for JSON parsing in Phoenix
config :phoenix, :json_library, Jason

ip =
  env!("HTTP_INTERFACE", fn val ->
    with [_] <- String.split(val, "."),
         [_] <- String.split(val, ":") do
      raise "Invalid IP address specified"
    else
      parts -> parts |> Enum.map(&String.to_integer/1) |> List.to_tuple()
    end
  end)

ecto_socket_options = if env!("ECTO_IPV6", :boolean!), do: [:inet6], else: []

config :your_app, YourApp.Repo,
  # ssl: true,
  url: env!("DATABASE_URL", :string!),
  pool: env!("PG_POOL", :module?),
  pool_size: env!("POOL_SIZE", :integer!),
  socket_options: ecto_socket_options,
  stacktrace: env!("ECTO_STACKTRACE", :boolean),
  show_sensitive_data_on_connection_error:
    env!("SHOW_SENSITIVE_DATA_ON_CONNECTION_ERROR", :boolean)

if env!("ENABLE_DISTRIBUTED_MODE", :boolean) do
  config :your_app, :dns_cluster_query, env!("DNS_CLUSTER_QUERY", :string)
end

config :your_app, YourAppWeb.Endpoint,
  cache_static_manifest: env!("PHX_CACHE_STATIC_MANIFEST", :string?),
  check_origin: env!("HTTP_CHECK_ORIGIN", :boolean),
  http: [ip: ip, port: env!("PORT", :integer!)],
  secret_key_base: env!("SECRET_KEY_BASE", :string!),
  # Used to build URLs
  url: [
    host: env!("PHX_HOST", :string!),
    port: env!("PHX_URL_PORT", :integer!),
    scheme: env!("PHX_URL_SCHEME", :string!)
  ]

# ## SSL Support
#
# To get SSL working, you will need to add the `https` key
# to your endpoint configuration:
#
#     config :your_app, YourAppWeb.Endpoint,
#       https: [
#         ...,
#         port: 443,
#         cipher_suite: :strong,
#         keyfile: System.get_env("SOME_APP_SSL_KEY_PATH"),
#         certfile: System.get_env("SOME_APP_SSL_CERT_PATH")
#       ]
#
# The `cipher_suite` is set to `:strong` to support only the
# latest and more secure SSL ciphers. This means old browsers
# and clients may not be supported. You can set it to
# `:compatible` for wider support.
#
# `:keyfile` and `:certfile` expect an absolute path to the key
# and cert in disk or a relative path inside priv, for example
# "priv/ssl/server.key". For all supported SSL configuration
# options, see https://hexdocs.pm/plug/Plug.SSL.html#configure/1
#
# We also recommend setting `force_ssl` in your config/prod.exs,
# ensuring no data is ever sent via http, always redirecting to https:
#
#     config :your_app, YourAppWeb.Endpoint,
#       force_ssl: [hsts: true]
#
# Check `Plug.SSL` for all available options in `force_ssl`.
#
# In order to use HTTPS in development, a self-signed
# certificate can be generated by running the following
# Mix task:
#
#     mix phx.gen.cert
#
# Run `mix help phx.gen.cert` for more information.
#
# The `http:` config above can be replaced with:
#
#     https: [
#       port: 4001,
#       cipher_suite: :strong,
#       keyfile: "priv/cert/selfsigned_key.pem",
#       certfile: "priv/cert/selfsigned.pem"
#     ],
#
# If desired, both `http:` and `https:` keys can be
# configured to run both http and https servers on
# different ports.
```

--------------------------------

### Configure config/dev.exs for Phoenix

Source: https://dotenvy.hexdocs.pm/phoenix.html

Sets up development-specific features like code reloading, debug errors, and asset watchers.

```elixir
# config/dev.exs
import Config

# Compile-time configuration includes code_reloader, debug_errors, and force_ssl
# https://hexdocs.pm/phoenix/Phoenix.Endpoint.html#module-compile-time-configuration
config :your_app, YourAppWeb.Endpoint,
  code_reloader: true,
  debug_errors: true,
  force_ssl: false,
  # Watch static and templates for browser reloading.
  live_reload: [
    patterns: [
      ~r"priv/static/(?!uploads/).*(js|css|png|jpeg|jpg|gif|svg)$",
      ~r"priv/gettext/.*(po)$",
      ~r"lib/your_app_web/(controllers|live|components)/.*(ex|heex)$"
    ]
  ],
  # The watchers configuration can be used to run external
  # watchers to your application. For example, we can use it
  # to bundle .js and .css sources.
  # Watchers can be configured at runtime but are unlikely to change
  watchers: [
    esbuild: {Esbuild, :install_and_run, [:your_app, ~w(--sourcemap=inline --watch)]},
    tailwind: {Tailwind, :install_and_run, [:your_app, ~w(--watch)]}
  ]

# Compile-time config
config :phoenix_live_view,
  debug_heex_annotations: true,
  enable_expensive_runtime_checks: true

# Enable dev routes for dashboard and mailbox (compile-time config)
config :your_app, dev_routes: true

# Do not include metadata nor timestamps in development logs
config :logger, :console, format: "[$level] $message\n"
```

--------------------------------

### Configure config/test.exs for Phoenix

Source: https://dotenvy.hexdocs.pm/phoenix.html

Sets logging levels for the test environment.

```elixir
# config/test.exs
import Config

# Print only warnings and errors during test
config :logger, level: :warning
```

--------------------------------

### source(files, opts \ [])

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Accumulates values from the given input sources and stores them for later retrieval via env! functions.

```APIDOC
## source(files, opts \ [])

### Description
Accumulates values from the given input(s). The accumulated values are stored via a side effect function to make them available to the env!/2 and env!/3 functions.

### Parameters
- **files** (input_source) - Required - A path to an env file or a map of key-value pairs.
- **opts** (Keyword) - Optional - Configuration options for the source operation.
```

--------------------------------

### Configure runtime environment variables

Source: https://dotenvy.hexdocs.pm/getting_started.html

Define environment variables in runtime.exs using the env! macro.

```elixir
config :example, :secret, env!("SECRET", :string!)
```

--------------------------------

### Dotenvy.source(inputs, opts)

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Accumulates values from the given input(s) and stores them for use by env!/2 and env!/3 functions. Inputs are processed from left to right, with right-most inputs taking precedence.

```APIDOC
## Dotenvy.source(inputs, opts)

### Description
Accumulates values from the given input(s) and stores them via a side effect function. This function acts as a merging operation for maps or paths to environment files.

### Signature
`source(inputs :: input_source() | [input_source()], opts :: keyword()) :: {:ok, %{optional(String.t()) => String.t()}} | {:error, any()}`

### Parameters
- **inputs** (input_source() | [input_source()]) - Required - A single source or a list of sources (maps or file paths) to be merged.
- **opts** (keyword()) - Optional - Configuration options for the parsing process.

### Options
- **:parser** (module) - Module implementing the Dotenvy.parse/3 callback. Default: Dotenvy.Parser.
- **:require_files** (boolean | [String.t()]) - Specifies which files must be present. Default: false.
- **:side_effect** (function) - An arity 1 function called after successful parsing to store the values. Default: internal function storing values in the process dictionary.

### Example
```elixir
# Parsing a single file
Dotenvy.source(".env")

# Merging multiple sources with precedence
Dotenvy.source([
  "#{config_env()}.env",
  "#{config_env()}.override.env",
  System.get_env()
])
```
```

--------------------------------

### Executing Shell Commands for Environment Variables

Source: https://dotenvy.hexdocs.pm/1password.html

Use System.shell to execute a script and capture the environment output.

```elixir
System.shell(~s'bash -c "source secrets.sh && env"')
```

--------------------------------

### Source environment variables in config/runtime.exs

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Load environment variables during runtime, prioritizing system environment variables.

```elixir
import Config
import Dotenvy

env_dir = System.get_env("RELEASE_ROOT") || Path.expand("./envs/")
  
source!([
    Path.absname(".env", env_dir),
    Path.absname(".#{config_env()}.env", env_dir),
    Path.absname(".#{config_env()}.overrides.env", env_dir),
    System.get_env()
  ])
```

--------------------------------

### Update source precedence with variable interpolation

Source: https://dotenvy.hexdocs.pm/

Include System.get_env() before .env files to make system variables available for interpolation within the files.

```elixir
# in dotenvy 0.5.0 or before:
source(["#{config_env()}.env", "#{config_env()}.override.env"])

# should be changed to the following in dotenvy 0.6.0:
source([System.get_env(), "#{config_env()}.env", "#{config_env()}.override.env", System.get_env()])
```

--------------------------------

### Define values with different quoting styles

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Demonstrates simple assignment, interpolation, and multi-line values.

```text
SIMPLE=xyz123
INTERPOLATED="Multiple\nLines and variable substitution: ${SIMPLE}"
NON_INTERPOLATED='raw text without variable interpolation'
MULTILINE = """
long text here,
e.g. a private SSH key
"""
```

--------------------------------

### Define Phoenix compile-time configuration

Source: https://dotenvy.hexdocs.pm/minimal.html

Certain framework-level settings like routes and LiveView annotations must be defined at compile-time to influence application generation.

```elixir
# Compile-time config
config :phoenix_live_view,
  debug_heex_annotations: true,
  enable_expensive_runtime_checks: true

# Enable dev routes for dashboard and mailbox (compile-time config)
config :your_app, dev_routes: true
```

--------------------------------

### Resolve absolute paths for .env files

Source: https://dotenvy.hexdocs.pm/livebooks.html

Use Path.expand and Path.absname to ensure .env files are located correctly regardless of the current working directory.

```elixir
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")

source!([
    Path.absname(".env", env_dir_prefix),
    Path.absname(".#{config_env()}.env", env_dir_prefix),
    Path.absname(".#{config_env()}.overrides.env", env_dir_prefix),
    System.get_env()
  ])
```

--------------------------------

### Define environment-specific variables

Source: https://dotenvy.hexdocs.pm/getting_started.html

Declare variables in the environment-specific .env file.

```text
SECRET=my-secret-dev
```

--------------------------------

### Ensure Mix task configuration loading

Source: https://dotenvy.hexdocs.pm/

Methods to ensure application configuration is loaded when executing custom Mix tasks.

```elixir
def run(_args) {
  Mix.Task.run("app.config")
  # ...
}
```

```bash
mix do app.config other.task
```

```elixir
# mix.exs
defp aliases do
    [
      "other.task": ["app.config", "other.task"]
    ]
```

--------------------------------

### Update source precedence for system environment variables

Source: https://dotenvy.hexdocs.pm/

Include System.get_env() as the final argument to ensure system variables take precedence over .env files.

```elixir
# in dotenvy 0.5.0 or before:
source(["#{config_env()}.env", "#{config_env()}.override.env"])

# should be changed to the following in dotenvy 0.6.0:
source(["#{config_env()}.env", "#{config_env()}.override.env", System.get_env()])
```

--------------------------------

### Update Dockerfile for Dotenvy

Source: https://dotenvy.hexdocs.pm/flyio.html

Add the COPY command to the Dockerfile to ensure the environment directory is included in the release build.

```dockerfile
# ... existing Docker stuff...

# Compile the release
RUN mix compile

# Changes to config/runtime.exs don't require recompiling the code
COPY config/runtime.exs config/

COPY rel rel

# <---- make the directory of envs available to the release!!!
COPY envs envs

RUN mix release

# ... existing Docker stuff cont'd...
```

--------------------------------

### Dotenvy.Parser.parse/3

Source: https://dotenvy.hexdocs.pm/Dotenvy.Parser.html

Parses the provided .env file contents, substituting and merging them with existing variables. Supports custom system command execution via options.

```APIDOC
## Dotenvy.Parser.parse(contents, vars \\ %{}, opts \\ [])

### Description
Parses the given `contents`, substituting and merging with the given `vars`.

### Parameters
- **contents** (String) - Required - The raw content of the .env file.
- **vars** (Map) - Optional - A map of existing variables to merge with the parsed results.
- **opts** (Keyword List) - Optional - Configuration options for the parser.

### Options
- **:sys_cmd_fn** (Function) - An arity 3 function returning a tuple matching the spec for System.cmd/3. Defaults to System.cmd/3.
- **:sys_cmd_opts** (Keyword List) - Options passed as the 3rd argument to the :sys_cmd_fn.

### Example
```elixir
# Disabling system commands
Dotenvy.Parser.parse(contents, %{}, sys_cmd_fn: fn _cmd, _args, _opts -> {"", 0} end)
```
```

--------------------------------

### Validate variable names

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Regex pattern for valid environment variable names.

```regex
[a-zA-Z_]+[a-zA-Z0-9_]*
```

--------------------------------

### Define multi-line values

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Use triple-quoted heredoc syntax for multi-line strings like private keys.

```text
PRIVATE_KEY="""
-----BEGIN RSA PRIVATE KEY-----
...
HkVN9...
...
-----END DSA PRIVATE KEY-----
"""
```

--------------------------------

### Configure build_per_environment in mix.exs

Source: https://dotenvy.hexdocs.pm/minimal.html

Set build_per_environment to false in the project configuration to reuse compiled artifacts across environments.

```elixir
  def project do
    [
      app: :my_app,
      version: "0.1.0",
      elixir: "~> 1.18",
      start_permanent: Mix.env() == :prod,
      deps: deps(),
      releases: releases(),
      build_per_environment: false
    ]
  end
```

--------------------------------

### env!(variable, type, default)

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Reads an environment variable and converts its output, or returns a provided default value if the variable is missing.

```APIDOC
## env!(variable, type, default)

### Description
Reads an env variable and converts its output or returns a default value.

### Parameters
- **variable** (String) - Required - The name of the environment variable to read.
- **type** (Atom) - Required - The type to convert the value to.
- **default** (Any) - Required - The value to return if the environment variable is not set.
```

--------------------------------

### Handling missing environment variables

Source: https://dotenvy.hexdocs.pm/getting_started.html

The error message displayed when a required environment variable is missing from the contract.

```text
** (RuntimeError) Environment variable PASSWORD not set
```

--------------------------------

### Defining variables in env files

Source: https://dotenvy.hexdocs.pm/getting_started.html

Setting a required variable within an environment configuration file.

```text
PASSWORD=xxxx
```

--------------------------------

### 1Password URI Syntax

Source: https://dotenvy.hexdocs.pm/1password.html

The standard URI format for referencing specific fields within a 1Password vault item.

```text
op://<vault-name>/<item-name>/[section-name/]<field-name>
```

--------------------------------

### Configuring non-strict string conversion

Source: https://dotenvy.hexdocs.pm/getting_started.html

Shows the configuration change to allow empty values by using the :string type instead of :string!.

```elixir
config :example, :password, env!("PASSWORD", :string)
```

--------------------------------

### Configure Phoenix Production Settings

Source: https://dotenvy.hexdocs.pm/phoenix.html

Defines compile-time configuration for the Phoenix endpoint and logger in production.

```elixir
import Config

# Compile-time configuration includes code_reloader, debug_errors, and force_ssl
# https://hexdocs.pm/phoenix/Phoenix.Endpoint.html#module-compile-time-configuration
config :your_app, YourAppWeb.Endpoint,
  code_reloader: false,
  debug_errors: false,
  force_ssl: false

# Do not print debug messages in production
config :logger, level: :info
```

--------------------------------

### Read and convert environment variables with env!/2

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Reads an environment variable and converts it to a specified type, raising an error if conversion fails.

```elixir
@spec env!(variable :: binary(), type :: Dotenvy.Transformer.conversion_type()) ::
  any() | no_return()
```

```elixir
iex> env!("PORT", :integer)
5432
iex> env!("ENABLED", :boolean)
true
```

--------------------------------

### Define environment variables in envs/dev.env

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Store non-sensitive defaults in a dedicated envs directory.

```text
API_KEY=xyz
AWS_REGION="us-east-1"
HTTP_CLIENT=HTTPoison
```

--------------------------------

### Resolve Environment Directory Path

Source: https://dotenvy.hexdocs.pm/releases.html

Use the RELEASE_ROOT environment variable or a relative path to determine the absolute location of the environment configuration directory.

```elixir
env_dir_prefix = System.get_env("RELEASE_ROOT") || Path.expand("./envs")
```

--------------------------------

### Accessing 1Password Secrets in .env Files

Source: https://dotenvy.hexdocs.pm/1password.html

Use the $() syntax to execute the op command directly within .env files for Dotenvy version 1.0.0 and later.

```bash
DB_PASSWORD=$(op read op://MyVault/FooDatabase/password);
API_KEY=$(op read op://MyVault/ImportantAPI/key);
```

--------------------------------

### Cherry-pick system variables

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Explicitly passing specific system variables to be used for substitution.

```elixir
  iex> Dotenvy.source([
    %{"HOME" => System.get_env("HOME")},
    ".env",
    System.get_env()
  ])
```

--------------------------------

### Implement parse callback

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Defines the callback signature for custom parser implementations.

```elixir
@callback parse(contents :: binary(), vars :: map(), opts :: keyword()) ::
  {:ok, map()} | {:error, any()}
```

--------------------------------

### Export parsed variables to system environment

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Using System.put_env/1 to make parsed variables available globally in the application.

```elixir
iex> {:ok, parsed_vars} = Dotenvy.source([".env", System.get_env()])
iex> System.put_env(parsed_vars)
```

--------------------------------

### Accessing environment variables via System

Source: https://dotenvy.hexdocs.pm/getting_started.html

Demonstrates that Dotenvy does not export variables to the system environment.

```elixir
iex> System.get_env("SECRET")
nil
```

--------------------------------

### env!(variable, type, default)

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Reads an environment variable and converts its value to the specified type, or returns a provided default value if the variable is not set.

```APIDOC
## env!(variable, type, default)

### Description
Reads an env variable and converts its output or returns a default value. The default value is returned as-is without conversion, and is only used when the variable is not set.

### Parameters
- **variable** (binary) - Required - The name of the environment variable to read.
- **type** (Dotenvy.Transformer.conversion_type) - Required - The target type for conversion.
- **default** (any) - Required - The value to return if the variable is not set.

### Example
```elixir
env!("PORT", :integer, 5432)
# Returns: 5433
```
```

--------------------------------

### Restrict system commands in Dotenvy.Parser

Source: https://dotenvy.hexdocs.pm/Dotenvy.Parser.html

Provide a custom function to the :sys_cmd_fn option to whitelist specific commands and raise an error for unauthorized attempts.

```elixir
iex> Dotenvy.Parser.parse(contents, %{}, sys_cmd_fn: fn
  "op", args, opts -> System.cmd("op", args, opts)
  _cmd, _args, _opts -> raise "Command not allowed"
end)
```

--------------------------------

### env!(variable, type \ :string)

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Reads the specified environment variable and converts its value to the requested type.

```APIDOC
## env!(variable, type \ :string)

### Description
Reads the given env variable and converts its value to the given type.

### Parameters
- **variable** (String) - Required - The name of the environment variable to read.
- **type** (Atom) - Optional - The type to convert the value to (defaults to :string).
```

--------------------------------

### Define input_source type

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Defines the accepted input types for environment sources, supporting file paths or maps.

```elixir
@type input_source() :: String.t() | %{optional(String.t()) => String.t()}
```

--------------------------------

### Execute command substitution

Source: https://dotenvy.hexdocs.pm/dotenv-file-format.html

Use $(command) syntax to inject output from shell commands into variables.

```bash
API_KEY=$(op read op://MyVault/SomeService/api_key)
```

--------------------------------

### Define source! function specification

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

This specification defines the input types and return behavior for the source! function.

```elixir
@spec source!(files :: binary() | [binary()], opts :: keyword()) ::
  %{optional(String.t()) => String.t()} | no_return()
```

--------------------------------

### Define source/2 specification

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

The function signature and return type specification for source/2.

```elixir
@spec source(inputs :: input_source() | [input_source()], opts :: keyword()) ::
  {:ok, %{optional(String.t()) => String.t()}} | {:error, any()}
```

--------------------------------

### Read environment variables with default values using env!/3

Source: https://dotenvy.hexdocs.pm/Dotenvy.html

Reads an environment variable with a fallback default value. The default value is returned as-is without conversion.

```elixir
@spec env!(
  variable :: binary(),
  type :: Dotenvy.Transformer.conversion_type(),
  default :: any()
) :: any() | no_return()
```

```elixir
iex> env!("PORT", :integer, 5432)
5433

iex> env!("NOT_SET", :boolean, %{not: "converted"})
%{not: "converted"}

iex> System.put_env("HOST", "")
iex> env!("HOST", :string!, "localhost")
** (RuntimeError) Error converting HOST to string!: non-empty value required
```

--------------------------------

### Apply custom transformation function

Source: https://dotenvy.hexdocs.pm/cheatsheet.html

Transform environment strings into complex Elixir types using custom functions.

```text
PHX_IP="0, 0, 0, 0, 0, 0, 0, 0"
```

```elixir
config :feenix, FeenixWeb.Endpoint,
    http: [
      # Enable IPv6 and bind on all interfaces.
      ip: env!("PHX_IP", fn ip -> 
        ip 
        |> String.split(",") 
        |> Enum.map(&String.trim/1) 
        |> Enum.map(&String.to_integer/1) 
        |> List.to_tuple()
      end)
    ],
```