SystemEnv (system_env v0.1.2)

Helpers for handling OS environment variables.

It helps to:

cast values of environment variables
provide user-friendly error messages

Summary

Types

data_type()

option()

options()

result()

Functions

fetch_env!(name)

fetch_env!(name, type_or_opts)

fetch_env!(name, type, opts)

Gets the value of the given environment variable, and casts it into given type.

get_env(name)

get_env(name, type)

Gets the value of the given environment variable, and casts it into given type.

Types

data_type()

@type data_type() :: :boolean | :integer | :float | :string | :atom

option()

@type option() :: {:message, String.t()}

options()

@type options() :: [option()]

result()

@type result() :: boolean() | integer() | float() | String.t() | atom()

Functions

fetch_env!(name)

@spec fetch_env!(String.t()) :: String.t()

fetch_env!(name, type_or_opts)

@spec fetch_env!(String.t(), data_type()) :: result()

@spec fetch_env!(String.t(), options()) :: String.t()

fetch_env!(name, type, opts)

@spec fetch_env!(String.t(), data_type(), options()) :: result()

Gets the value of the given environment variable, and casts it into given type.

If the environment variable is not set, raises an error.

Examples

iex> SystemEnv.fetch_env!("NOT_SET", :boolean)
** (SystemEnv.EnvError) environment variable NOT_SET is missing
    (system_env) lib/system_env.ex:134: SystemEnv.fetch_env!/3
    iex:1: (file)

# export PHX_SERVER=true
iex> SystemEnv.fetch_env!("PHX_SERVER", :boolean)
true

# export DB_POOL_SIZE=10
iex> SystemEnv.fetch_env!("DB_POOL_SIZE", :integer)
10

# export PERCENT=0.95
iex> SystemEnv.fetch_env!("PERCENT", :float)
0.95

# export USER=billy
iex> SystemEnv.fetch_env!("USER", :string)
"billy"

# export USER=billy
iex> SystemEnv.fetch_env!("USER", :atom)
:billy

# pass extra message
iex> SystemEnv.fetch_env!(
...>   "DATABASE_URL",
...>   "Set it to something like: ecto://USER:PASS@HOST/DATABASE"
...> )
** (SystemEnv.EnvError) environment variable DATABASE_URL is missing. Set it to something like: ecto://USER:PASS@HOST/DATABASE
    (system_env) lib/system_env.ex:134: SystemEnv.fetch_env!/3
    iex:1: (file)

get_env(name)

@spec get_env(String.t()) :: String.t()

get_env(name, type)

@spec get_env(String.t(), data_type()) :: result()

Gets the value of the given environment variable, and casts it into given type.

If the environment variable is not set, returns nil.

Examples

iex> SystemEnv.get_env("NOT_SET", :boolean)
nil

# export PHX_SERVER=true
iex> SystemEnv.get_env("PHX_SERVER", :boolean)
true

# export DB_POOL_SIZE=10
iex> SystemEnv.get_env("DB_POOL_SIZE", :integer)
10

# export PERCENT=0.95
iex> SystemEnv.get_env("PERCENT", :float)
0.95

# export USER=billy
iex> SystemEnv.get_env("USER", :string)
"billy"

# export USER=billy
iex> SystemEnv.get_env("USER", :atom)
:billy