A configuration is a list of key-value string pairs.
Reading configuration
Using the schema validator conformist it is easy to validate and decode configuration values. Conformist schemas can express a richer set of requirements than static types, which can be used in services to validate configurations at start time.
Validating configuration when starting services can lead to run-time exceptions, but they occur early in the app lifecycle. This minimizes the feedback loop and makes sure, that services start only with valid configuration.
project_root_path contains the path to the root of the project/app. Its value is known at app start, thus not requiring it to be a function. It reads the value of PROJECT_ROOT_PATH. If that env variable is not set, it reads the current working directory of the process.
val project_root_path : string
read_env_file () reads an .env file from the project root directory and returns the key-value pairs as data. If SIHL_ENV is set to testing, .env.testing is read. Otherwise .env is read. If the file doesn't exist, empty data is returned.
read schema returns the decoded, statically typed version of configuration t of the schema. This is used in services to declaratively define a valid configuration.
The configuration data t is merged with the environment variable and, if present, an .env file.
It fails with Exception and prints descriptive message of invalid configuration.
val read_string : string ->string option
read_string key returns the configuration value with key if present. The function is memoized, the first call caches the returned value and subsequent calls are fast.
val read_int : string ->int option
read_int key returns the configuration value with key if present. the first call caches the returned value and subsequent calls are fast.
val read_bool : string ->bool option
read_bool key returns the configuration value with key if present. the first call caches the returned value and subsequent calls are fast.
val is_testing : unit -> bool
is_testing () returns true if SIHL_ENV is set to testing.