Level:    zap.NewAtomicLevelAt(zap.FatalLevel),
		Encoding: "console",
	}
	cfg.Endpoints = etcdEndpoints
	cfg.CoreDNSPath = env.Get(EnvEtcdCoreDNSPath, kvs.Get(CoreDNSPath))
	// Default path prefix for all keys on etcd, other than CoreDNSPath.
	cfg.PathPrefix = env.Get(EnvEtcdPathPrefix, kvs.Get(PathPrefix))
	if etcdSecure {
		cfg.TLS = &tls.Config{
			RootCAs: rootCAs,
		}

	timeoutCtx, cancel := context.WithTimeout(ctx, defaultContextTimeout)
	defer cancel()
	resp, err := client.Get(timeoutCtx, key)
	if err != nil {
		etcdLogOnceIf(ctx, err, "etcd-retrieve-keys")
		return nil, etcdErrToErr(err, client.Endpoints())
	}
	if resp.Count == 0 {
		return nil, errConfigNotFound
	}
	for _, ev := range resp.Kvs {
		if string(ev.Key) == key {
			return ev.Value, nil
		}
	}