Function apply_datadog_env 

pub fn apply_datadog_env(
    base: &mut Value,
    overwrite: bool,
) -> Result<(), String>

Reads every modeled Datadog key from the environment and writes decoded values into base.

Applies the canonical proxy variables (HTTP_PROXY/HTTPS_PROXY) as well. When overwrite is true an environment value replaces whatever is already at its path (environment wins over the file); when false it fills only an absent path (the file wins).

Errors

Returns a message naming the environment variable when its value is malformed for the key’s declared shape. At startup this aborts the boot rather than silently dropping the value.