Data.Yaml.Config

Functionality for using YAML as configuration files

In particular, merging environment variables with yaml values

loadYamlSettings is a high-level API for loading YAML and merging environment variables. A yaml value of _env:ENV_VAR:default will lookup the environment variable ENV_VAR.

On a historical note, this code was taken directly from the yesod web framework's configuration module.

Documentation

applyCurrentEnv

Arguments

:: Bool

require an environment variable to be present?

-> Value

-> IO Value

getCurrentEnv :: IO (HashMap Text Text)

applyEnvValue

Arguments

:: Bool

require an environment variable to be present?

-> HashMap Text Text

-> Value

-> Value

loadYamlSettings

Arguments

:: FromJSON settings

=> [FilePath]

run time config files to use, earlier files have precedence

-> [Value]

any other values to use, usually from compile time config. overridden by files

-> EnvUsage

-> IO settings

Load the settings from the following three sources:

• Run time config files
• Run time environment variables
• The default compile time config file

data EnvUsage

ignoreEnv :: EnvUsage

useEnv :: EnvUsage

requireEnv :: EnvUsage

useCustomEnv :: HashMap Text Text -> EnvUsage

requireCustomEnv :: HashMap Text Text -> EnvUsage