}

// Lookup - initializes LDAP config, overrides config, if any ENV values are set.
func Lookup(s config.Config, rootCAs *x509.CertPool) (l Config, err error) {
	l = Config{}

	// Purge all removed keys first
	kvs := s[config.IdentityLDAPSubSys][config.Default]
	if len(kvs) > 0 {
		for _, k := range removedKeys {
			kvs.Delete(k)
		}
		s[config.IdentityLDAPSubSys][config.Default] = kvs
	}

	// Set of env vars for the sub-system to validate.
	candidates := set.CreateStringSet(subSysEnvVars...)

	// Remove all default target env vars from the candidates set (as they
	// are valid).
	for _, param := range validKeys {
		paramEnvName := getEnvVarName(subSys, Default, param)
		candidates.Remove(paramEnvName)
	}

	isSingleTarget := SubSystemsSingleTargets.Contains(subSys)