Golang 从哪里获取根 CA？

crypto/tls.Config.RootCAs states https://golang.org/pkg/crypto/tls/#Config

// RootCAs defines the set of root certificate authorities
// that clients use when verifying server certificates.
// If RootCAs is nil, TLS uses the host's root CA set.

在 Linux 上，“主机的根 CA 集”是从哪里获取的？我需要知道这一点才能全局添加另一个信任的根 CA。

它搜索以下位置：https://golang.org/src/crypto/x509/root_linux.go https://golang.org/src/crypto/x509/root_linux.go

excerpt

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package x509

// Possible certificate files; stop after finding one.
var certFiles = []string{
    "/etc/ssl/certs/ca-certificates.crt",                // Debian/Ubuntu/Gentoo etc.
    "/etc/pki/tls/certs/ca-bundle.crt",                  // Fedora/RHEL 6
    "/etc/ssl/ca-bundle.pem",                            // OpenSUSE
    "/etc/pki/tls/cacert.pem",                           // OpenELEC
    "/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem", // CentOS/RHEL 7
    "/etc/ssl/cert.pem",                                 // Alpine Linux
}