Function override_var 

pub fn override_var(entry: &str, kind: &str, field_path: &str) -> String

The environment variable that overrides one option of one port entry: <ENTRY>_<KIND>_<FIELD>, uppercased, nested path segments joined with _.

assert_eq!(kernel::override_var("primary", "opensearch", "url"), "PRIMARY_OPENSEARCH_URL");
assert_eq!(
    kernel::override_var("source", "postgres", "connection_url.password"),
    "SOURCE_POSTGRES_CONNECTION_URL_PASSWORD",
);