Add a GetCertificateWithContext function

[ankon]

This basically would allow us to pass a context into the "certmagic world", from which it then would get passed through back to our storage implementation.

The reason we want that is so that we can actually set up application performance monitoring by instrumenting the calls.

Note that this does add a new public function, but unless you specifically set your GetCertificate in the TLSConfig to something that uses this function, everything should stay the same.

Our setup looks like this, very simplified:

certmagicConfig.Issuers = []certmagic.Issuer{acmeIssuer}

tlsConfig := certmagicConfig.TLSConfig()
tlsConfig.GetCertificate = func(clientHelloInfo *tls.ClientHelloInfo) (*tls.Certificate, error) {
	txn := monitoring.StartTransaction("TLS/GetCertificate")
	defer txn.End()
	txn.AddAttribute("hostname", clientHelloInfo.ServerName)
	txn.AddAttribute("supportedVersions", supportedVersionsToString(clientHelloInfo.SupportedVersions))

	// ... do some checks here to make sure we want to handle this request

	ctx := newrelic.NewContext(context.Background(), txn)
	cert, err := certmagicConfig.GetCertificateWithContext(ctx, clientHelloInfo)
	if err != nil {
		// ... review the error and possible ignore it/handle it differently
	}
	return cert, err
}

[mholt]

Hi, sorry for the lack of reply -- I'll be getting around to this soon as I prepare the Caddy 2.7 beta 1 release :)

[mholt]

LGTM. Thank you for the enhancement!