title: Where is Golang picking up root CAs from?
body: <p><code>crypto/tls.Config.RootCAs</code> <a href="https://golang.org/pkg/crypto/tls/#Config" rel="noreferrer">states</a></p>
  
  <pre><code>// 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.
  </code></pre>
  
  <p><strong>On Linux, where are "the host's root CA set" picked up from?</strong> I need to know this to be able to globally add another root CA to trust.</p>